Universe

The Big Dipper is high in the sky at nightfall at this time of year, with W-shaped Cassiopeia low in the sky. If you look shortly before dawn, though, they’ve moved. The dipper is in the northwest, with Cassiopeia the same height in the northeast. The stars haven’t moved at all, of course. Instead, they’ve changed position in our sky because Earth is turning on its axis. All the stars appear to revolve around the North Star — the point the axis aims at. Except for the Sun, Moon, and planets, everything appears to turn together. The stars all maintain their relative positions from night to night, year to year, and even century to century. That unified rotation may have played a role in the name for everything there is: universe. The word comes from Latin roots that mean “one” and “to turn.” So “universe” can be taken to mean “everything is turning together.” A 19th-century astronomy textbook, in fact, said that was what the word was intended to convey. Earth was a static platform around which everything else turned. Everything beyond Earth belonged to the universe. A more-modern view of the word’s early meaning is “turned into one.” In other words, everything belongs to a single framework. And today, universe means “everything there is” — including Earth. Our planet is no longer the hub of everything, but a part of it — bringing new vistas as it spins through the universe. We’ll talk about a debate over the extent of the universe tomorrow.   Script by Damond Benningfield

Natural Sciences
Published: April 23, 2020, 5 a.m.

Earth Day

Apollo 8 carried the first astronauts to the Moon, at the end of 1968. They orbited the Moon on Christmas Eve and Christmas Day. When they came home, they brought back a lot of close-ups of the lunar surface. But what really caught people’s attention were pictures of Earth — a blue-white marble rising above the stark lunar landscape. By that time, many people were concerned about our home world. There’d been a series of environmental disasters during the 1960s. And no one seemed to be doing anything about the problem. Inspired by those problems — and by the Space Age pictures of Earth — activists organized an event for April 22nd, 1970 — 50 years ago today. It became the first Earth Day. Although the environmental movement was fairly new then, Earth Day was a big success. And it led to some big changes. The Environmental Protection Agency was formed that year. And laws protecting the air, water, and endangered species soon followed. Earth Day has been celebrated every year since. And this year marks the event’s fiftieth anniversary. The theme is climate change — the problems caused by human activities. Astronauts may return to the Moon within the next few years. And they’ll snap many more pictures of Earth. But it’s unlikely that any of them will have the same impact as those taken half a century ago — pictures of a “pale blue marble” in the blackness of space. We’ll talk about everything beyond Earth tomorrow.   Script by Damond Benningfield

Natural Sciences
Published: April 22, 2020, 5 a.m.

Double Showers

The Lyrid meteor shower should be at its best tonight, after midnight. Under dark skies, away from city lights, you might see a few dozen “shooting stars” in all. The Lyrids are spawned by Comet Thatcher. This ball of ice and rock orbits the Sun once every 415 years. It sheds grains of solid material on each orbit. Earth passes through this trail of debris every April, creating the meteor shower. Last year, a second shower was taking place at the same time as the Lyrids. It wasn’t much — tracking cameras detected about a dozen meteors. But it suggests that a big comet could be headed our way. The shower was called the 15-Bootids. It was detected by cameras in Europe and the Middle East. Scientists used images from multiple cameras to plot the paths of these meteors. That allowed them to trace their original orbits around the Sun. From that, the scientists found that the bits of debris might have come from a bright comet that last visited the inner solar system in the year 539. The speed of the meteors suggests the comet is big — perhaps 10 miles in diameter. Because its trail crosses Earth’s orbit, it could be a threat to hit our planet. And the presence of the shower suggests the comet could be getting close. The 15-Bootid shower isn’t expected to be seen again until 2027. In the meantime, though, check out the Lyrids. Find a dark, safe skywatching location, far from city lights, and look up — for fireworks from a comet.   Script by Damond Benningfield

Natural Sciences
Published: April 21, 2020, 5 a.m.

Lyrid Meteors

The mild nights of spring are generally a good time for skywatching. Only one thing is missing: a great meteor shower. The really good showers are clustered in fall and winter, with the Perseids of August sometimes joining the list. Although the season doesn’t offer a great shower, a pretty good one should reach its peak tomorrow night: the Lyrids. Under a dark sky, you might see a dozen or more meteors per hour between midnight and dawn. The number of meteors increases closer to dawn, as your part of Earth turns more directly into the meteor stream. And the Moon is new, so it’s not around to spoil the show. One good thing about meteors, though, is that you don’t have to wait for a shower to see them. A shower occurs when Earth passes through a stream of small bits of rock shed by a comet or asteroid, which happens a few times a year. But other bits of rocky debris are scattered throughout the solar system. So on any dark night, you can see several meteors racing across the sky. And while the meteors in a shower all appear to “rain” into the sky from a common point in space, these “random” meteors can come from any direction. So if you have a chance, look for the Lyrid meteor shower over the next few nights, and especially in the wee hours of Wednesday morning. If not, then take advantage of just about any clear, dark night to look for meteors flashing across the heavens. We’ll talk about another meteor shower tomorrow.   Script by Damond Benningfield

Natural Sciences
Published: April 20, 2020, 5 a.m.

Tracking Meteors

On any dark night, if you can get away from city lights, you might see a dozen or more meteors blazing across the sky. These streaks of light form when space rocks vaporize as they ram into Earth’s atmosphere at high speed. Scientists keep a close eye on meteors every night. They’ve set up networks of cameras that track them across the sky. That tells them about the origin of the meteors, and helps them track down bits of rock that fall to Earth as meteorites. There’s a network in Australia, and several in Europe, for example. And there are several in the United States as well. CAMS, for example, is operated by the SETI Institute. It has 80 cameras just in California, and coordinates with other networks around the world. Tracking a meteor’s path with different cameras allows scientists to plot its orbit around the Sun. That tells them where the meteor came from. It’s also allowed them to discover many new meteor showers. A NASA network is designed to help engineers understand the risks that space rocks pose to spacecraft. And the networks allow scientists to track down possible meteorites. Most of the rocks that hit Earth burn up in the atmosphere or fall into the oceans. But a few hit the ground. Tracking them down gives scientists a more complete picture of them – their origin, their composition, and much more. The cameras are seeing a lot of action right now, because a meteor shower is under way. More about that tomorrow.   Script by Damond Benningfield

Natural Sciences
Published: April 19, 2020, 5 a.m.

Meteorites

Not every rock on Earth is from Earth. Some of them came from asteroids, the Moon, and even Mars. In all, about 60,000 of these space rocks have been confirmed. Meteorites have survived the fiery plunge through Earth’s atmosphere to reach the ground. Some of them had orbited the Sun on their own since the birth of the solar system. Others were blasted off the surfaces of other bodies. More than 200, in fact, came from Mars, and almost 400 from the Moon. Meteorites fit into several broad categories. The most common are known as chondrites. They contain small pebbles of molten rock cemented together with other materials. The spheres probably formed in the early solar system, in the asteroid belt. A second category is achondrites. They consist mainly of once-molten rock. They probably are chips off the crusts of asteroids or other layered bodies. Another category is iron meteorites. They consist almost entirely of metals – mainly iron, with a large fraction of nickel. And the final category is a mixture of rock and metal, called stony irons. It’s hard to tell a meteorite from an Earth rock just by looking. Some have a dark crust – a result of their fiery journey through the atmosphere. Others are magnetic. But it generally takes an expert to identify them. Scientists study these rocks to learn about the birth and evolution of the solar system. And they’re especially keen to find meteorites that have just fallen to Earth. More about that tomorrow.   Script by Damond Benningfield

Natural Sciences
Published: April 18, 2020, 5 a.m.

Crater Hunting

An asteroid slammed into Earth almost 800,000 years ago. It left behind many souvenirs of the collision — black blobs of glass. But the spot where it hit has remained hidden — scientists haven’t found an impact crater. A recent study, though, says that could be because the crater is buried under volcanic rock. The impact melted millions of tons of rock and dirt and blasted them high into the sky. As this debris fell back to Earth, some of it cooled to form blobs of glass known as tektites. And the glass from this collision has been found all over the place — across Southeast Asia and Australia, in southern Africa, and even in Antarctica. In fact, the glass may be scattered across a tenth of Earth’s surface or more — the largest tektite field on the planet. A lot of research has zeroed in on Southeast Asia as the site of the impact — especially Laos and Cambodia. That includes the recent study. It places the impact in southern Laos. Researchers say several bits of evidence support that idea. The chemistry of the tektites suggests the impact took place in a volcanic region, for example. Rocks near the site were smashed by a close impact. And the region’s gravitational field reveals a possible crater below the rocks. It measures about 10 miles across. If that’s correct, then the asteroid slammed into a region that was already paved with volcanic rock. Fresh eruptions after the impact covered up the crater — hiding a cosmic scar.   Script by Damond Benningfield

Natural Sciences
Published: April 17, 2020, 5 a.m.

Relics

The oldest bits of material on Earth weren’t born here. Instead, they were born around dying stars — hundreds of millions of years before the formation of the Sun, Earth, and the rest of the solar system. The objects are solid grains a few millionths of an inch across. They formed from material expelled from dying stars. They blew through the galaxy until they reached the cloud of gas and dust that was giving birth to the solar system. They combined with other materials in that cloud to form a space rock. That rock — or a part of it — fell to Earth in 1969. It plunged through the atmosphere, then shattered when it hit the ground, in Australia. More than 200 pounds of debris were recovered. Scientists at the Field Museum in Chicago recently studied some of that debris. They used acid to dissolve the stuff that formed inside the solar system, leaving the grains from beyond it. They measured different forms of certain elements inside the grains. The ratio of those elements — especially neon — told them how long the grains had been in space. And that gave them a rough age for the grains. More than half of the grains were older than the solar system — some by a billion years or more. And the oldest one could pre-date the solar system by three billion years. Astronomers can learn about the conditions in which our solar system was born from these ancient relics — the oldest solid particles on Earth. More about rocks from space tomorrow.   Script by Damond Benningfield

Natural Sciences
Published: April 16, 2020, 5 a.m.

Moon and Mars

One of the goals of the missions to Mars is to find signs of life. Some of the best signs to date are periodic “burps” of methane – a compound that can be produced by living organisms. But the burps aren’t common – and they’re hard to see. In June, for example, the Curiosity rover detected the heaviest concentration of methane yet seen – more than 20 parts per billion. That’s dozens of times higher than the average level. But two spacecraft in Mars orbit passed above Curiosity within hours – and didn’t “sniff” a thing. Here on Earth, most of the methane in the atmosphere is produced by life – from bacteria to people. So methane on Mars could be produced by life as well. But it also could be produced by chemical reactions in the rocks, or by volcanoes. Several methane outbursts have been seen over the years – by orbiters, telescopes on Earth, and especially by Curiosity. Some of the rover’s detections have also been seen by Mars orbiters. But the one in June wasn’t. That might be because Curiosity was looking at night, the orbiters during the day. Sunlight destroys methane, so it might have disappeared by the time the orbiters rolled into view. Scientists are trying to pinpoint where the methane is coming from. That should help them figure out whether it’s produced by life on the Red Planet. Mars teams up with the Moon at first light tomorrow. It looks like an orange star above the Moon. Saturn and Jupiter line up to their upper right.   Script by Damond Benningfield

Natural Sciences
Published: April 15, 2020, 5 a.m.

Moon and Planets

The Moon is rolling past a trio of bright planets in the early morning sky this week. Tomorrow, Saturn will stand above the Moon. Brilliant Jupiter is to the upper right, with orange Mars to the lower left. Such a lineup is possible because the Moon and planets are all close to the ecliptic – the Sun’s path across the sky. The alignment isn’t quite perfect, though. The orbit of each body is tilted a bit with respect to the ecliptic, so each of them can appear a little above or below that path. Right now, Jupiter and Saturn sit almost directly atop the ecliptic. Mars is a degree or so south of it, with the Moon a couple of degrees farther. The Moon sometimes passes directly between Earth and one of the planets. In fact, it passed in front of Mars just a couple of months ago, blocking the planet from view. Because of the different angles of the orbits, though, such “coverups” don’t happen every time the Moon passes by a planet. Most of the time there’s just a close encounter, as there is with Saturn tomorrow. The Moon sometimes covers the Sun as well, creating an eclipse. And that’s where the word “ecliptic” comes from. Eclipses can happen only when the Moon is crossing the Sun’s path. If the Moon covers the Sun, it’s a solar eclipse. And if the Moon passes through Earth’s shadow, it’s a lunar eclipse — all made possible by passages across the ecliptic. We’ll have more about this early morning lineup tomorrow.   Script by Damond Benningfield

Natural Sciences
Published: April 14, 2020, 5 a.m.

Apollo 13

APOLLO 13: Okay, Houston, we’ve had a problem here. CAPCOM: This is Houston, say again, please. 13: Houston, we’ve had a problem. Perhaps no line in the history of the space program is better known than that one. Fifty years ago today, while more than halfway to the Moon, the crew of Apollo 13 — Jim Lovell, Fred Haise, and Jack Swigert — was in big trouble. LOVELL: It looks to me, looking out the hatch, that we are venting something. We are venting something out into space. An oxygen tank had exploded, damaging other systems and shutting down the mothership’s fuel cells. Without them it had no power — and no way to keep the crew alive. Flight director Gene Kranz prepped his team in Mission Control for the challenge: KRANZ: Okay, now, let’s everybody keep cool. We got the LM still attached, the LM spacecraft’s good, so if we need to get back home we’ve got a LM to do a good portion of it with. So let’s solve the problem, but let’s not make it any worse by guessing. Within an hour of the explosion, the astronauts were prepping their lunar lander, Aquarius, to serve as a lifeboat. They fired its main engine to put them on a path that would take them behind the Moon, then straight back to Earth. Over the following three and a half days, they relied on its power and engines to keep them alive and on course. And they relied on hundreds of engineers and technicians on the ground to solve problems and work out procedures. The astronauts were cold, thirsty, and miserable for much of the journey, but they made it home — surviving a famous problem in space.   Script by Damond Benningfield

Natural Sciences
Published: April 13, 2020, 5 a.m.

Galactic Fireworks

NGC 6946 is the galactic equivalent of the Fourth of July – the source of a whole lot of fireworks. Over the last century or so, it’s produced more supernovas than any other galaxy. And surveys have revealed almost 200 possible supernova remnants – the remains of stars that exploded in the last few thousand years. So NGC 6946 is also known as the Fireworks Galaxy. The galaxy is a beautiful spiral, like our home galaxy, the Milky Way. But it’s probably less than half the Milky Way’s diameter, with only a fraction as many stars. Yet it’s giving birth to many more stars than the Milky Way is. Many of those stars are hot and massive. They burn out quickly, then explode as a supernova, shining brighter than billions of “normal” stars. Supernovas are rare, though. On average, the Milky Way creates about one per century. And none has been seen here in four centuries. NGC 6946, on the other hand, has produced 10 of them since 1917. And one other star in the galaxy should have exploded but didn’t. It was the type of star that ends its life as a supernova. Over the last decade it brightened a bit, then vanished. Only a small blob of infrared light remains. The star could have collapsed to form a black hole. The infrared light could come from material falling into it – more fireworks from the Fireworks Galaxy. NGC 6946 is in the northeast before dawn, to the left of Deneb, the bright star at the tail of the swan.   Script by Damond Benningfield

Natural Sciences
Published: April 12, 2020, 5 a.m.

Vela Supernova

The Moon is the biggest single object in the night sky that’s visible to the eye alone. But many objects that are too faint to see are much bigger. An example is a nebula in the constellation Vela. It spans about 16 times the width of the Moon – almost the size of your fist held at arm’s length. And it’s getting bigger all the time. The Vela Supernova Remnant is 800 light-years away. It was born about 11,000 years ago as seen from Earth, when a supergiant star exploded, blasting its outer layers into space. As those layers ram into surrounding clouds of gas and dust, they glow. If you look across the entire spectrum – from radio waves to X-rays – the nebula looks like a mound of billowing clouds. When the star exploded, the outer layers were expelled at up to a few percent of the speed of light. So over the millennia, the nebula has inflated to a diameter of more than a hundred light-years. And it’s still expanding – at more than two million miles per hour. That rate is one way in which astronomers determine when the star exploded. Another is the star’s dead core, called a neutron star. It spins rapidly, emitting pulses of energy with each turn. Measuring how quickly it’s slowing down gives a rough estimate of when the neutron star formed – telling us when a massive star died. The Vela Supernova Remnant is in Vela, the sails, which hugs the southern horizon at nightfall. The nebula is big but faint, so you need a good telescope to see it.   Script by Damond Benningfield

Natural Sciences
Published: April 11, 2020, 5 a.m.

Solar Minimum

The Sun has been drowsy of late. Last year, it posted the equivalent of nine months without the dark magnetic storms known as sunspots. That’s the fourth-highest number in the last 170 years. This year began in similar fashion. And scientists expect the quiet times to continue. The Sun goes through an 11-year cycle of magnetic activity. At the cycle’s peak, scores of spots mar the Sun’s surface. And big explosions send radiation and particles racing through the solar system. When they reach Earth, these outbursts create intense displays of the northern lights. They also can damage satellites, disrupt some radio communications, and cause power outages on the surface. But at the cycle’s low point, called solar minimum, the Sun produces fewer outbursts. The current cycle began in 2008 and peaked in 2014. It was the quietest peak in decades. And the cycle has been especially quiet over the last couple of years. It produced no sunspots at all from November 14th through December 23rd — the longest spot-free span since 1996. And forecasters predict the cycle will reach its minimum this month. Some of the few sunspots that did appear late last year had an opposite magnetic polarity from those of the dying cycle. That suggests that the next cycle may be starting. Forecasters say the new cycle should peak in July 2025, at about the same level as the current one. So the Sun might stay drowsy for years to come.   Script by Damond Benningfield

Natural Sciences
Published: April 10, 2020, 5 a.m.

Epsilon Eridani

Frank Drake picked two target stars for Project Ozma, the first search for extraterrestrial intelligence. The first to be scanned was Tau Ceti. And the second was Epsilon Eridani, a close neighbor — just 10 and a half light-years away. It turns out, though, that Epsilon Eridani probably isn’t a good place to look for life. The star is young, so there hasn’t been much time for life to take hold. It probably produces a lot of ultraviolet and X-ray energy, which is dangerous. And its planets may face a steady barrage of space rocks. Epsilon Eridani is a little smaller and less massive than the Sun, and just a third as bright. Most studies say it’s between 200 million and 800 million years old, which is quite young. Because of its youth, it spins rapidly — about twice as fast as the Sun does. That generates a strong magnetic field. The field creates big outbursts that would shower planets with deadly radiation. Astronomers have discovered two possible planets in the system. But they’re bracketed by asteroid belts and a big “doughnut” of rocks and dust. Many of those space rocks fall toward the star. Some of them slam into the planets — making conditions especially hard for life. Project Ozma found no signals from Epsilon Eridani when it scanned the system with a radio telescope in 1960. And Drake repeated the observations 10 years ago — again coming up empty. So there’s no hint of a civilization in this messy star system.   Script by Damond Benningfield

Natural Sciences
Published: April 9, 2020, 5 a.m.

Tau Ceti

At least four planets orbit the star Tau Ceti, one of our closest neighbors. And two of those worlds are at the edges of the star’s habitable zone — the region that’s most comfortable for life. If civilizations inhabit those planets, though, they’re quiet. The first search for extraterrestrial intelligence scanned the planet, but didn’t hear a thing. Tau Ceti is 12 light-years away — just down the block. The star is smaller and cooler than the Sun, and about half as bright. And it’s about a billion years older, so there’s been more time for life to take hold there. But 60 years ago today, astronomer Frank Drake turned a radio telescope toward the system. It was one of two targets for Project Ozma — a hunt for other civilizations. In all, the telescope spent 200 hours scanning the two systems. But it found nothing out of the ordinary — ET wasn’t giving us a call. Life in the system would face a big challenge. A disk of rocky debris surrounds the planets. It contains many times more material than the asteroid belt in our own solar system. Big rocks from the disk might fall inward, slamming into a planet. That could destroy life on the planet. Project Ozma conducted only a short, narrow search for a specific sign of life at Tau Ceti. So despite the result, life could still exist on any or all of its planets. All we know for sure is that no one is beaming signals from Tau Ceti out into the galaxy. We’ll talk about Ozma’s other target tomorrow.   Script by Damond Benningfield

Natural Sciences
Published: April 8, 2020, 5 a.m.

Mars Equinox

One of the things that Earth and Mars have in common is the seasons. The two planets are tilted at almost the same angle. So the amount of sunlight received by their northern and southern hemispheres varies by quite a bit during the year. And the seasons are changing on Mars this week. It’s the autumnal equinox — the beginning of autumn in the northern hemisphere, and spring in the southern hemisphere. The season will last until the winter solstice, on September 2nd. Mars will be moving closer to the Sun throughout the season. It’ll be closest to the Sun around the start of southern summer. So the southern hemisphere will be warming up in a hurry. It’ll still be icy cold by Earthly standards. But the extra heat is enough to trigger big dust storms. And some of them can get big enough to cover the entire planet. The extra heat also causes part of the southern polar ice cap to vanish. Carbon dioxide atop the ice cap vaporizes and enters the atmosphere. That causes the air pressure to go up a bit across the entire planet. Later, as the hemisphere cools, the CO2 recondenses on the ice cap, making it bigger and thicker — one of the cycles of the Martian seasons. And Mars remains in good view in the early morning sky now. It forms the lower left end of a lineup of three planets at first light. Saturn is to the upper right of orange Mars, with brilliant Jupiter farther along the same line. Tomorrow: listening in on a nearby star.   Script by Damond Benningfield

Natural Sciences
Published: April 7, 2020, 5 a.m.

Venus and Aldebaran

A brilliant point of light in the western evening sky is sweeping past one that’s merely bright. The brilliant light is Venus, the “evening star.” It’s the brightest object in the night sky other than the Moon, so you can’t miss it. Despite its nickname, though, it’s not a star at all — it’s a planet. It’s the closest planet to Earth. And in some ways, it’s a near twin to our world. It’s about the same size, and it probably has a similar composition — a rocky crust and mantle around a dense core made of metal. In other ways, though, Venus is quite different. Its atmosphere is far hotter and denser than Earth’s. And it’s topped by an unbroken layer of clouds made of sulfuric acid. The merely bright light is Aldebaran, the ruddy eye of Taurus, the bull. It’s off to the left of Venus. And for the next two or three nights, it’s a little higher in the sky. Aldebaran looks less impressive than Venus, but that’s an illusion — a result of its great distance. Instead, it’s a giant star — dozens of times the diameter of the Sun. If it took the Sun’s place, it would incinerate Venus and turn Earth into a burned-out cinder. Watch Aldebaran and Venus over the next few nights. They’ll stand at about the same height on Wednesday or Thursday, depending on your latitude, before Venus pulls away. They’ll vanish from the evening sky later in the spring, then re-emerge in the morning sky — much closer together than they are now — in early July.   Script by Damond Benningfield

Natural Sciences
Published: April 6, 2020, 5 a.m.

Bright Galaxies

Canes Venatici, the hunting dogs, is awash in beautiful galaxies. In fact, four of the most prominent galaxies in our night sky congregate in one quadrant of the constellation. All four of them are spiral galaxies, like our own Milky Way. The most famous member of that quartet is M51, the Whirlpool Galaxy. It actually consists of two galaxies. One is a bright spiral that we see face on. It’s about half the diameter of the Milky Way. The second galaxy is much smaller — a yellow blob of stars. It’s flying past the bigger galaxy, pulling out a great ribbon of material — and triggering the birth of many new stars. M94 is near Cor Caroli, the constellation’s brightest star. It, too, is a busy star factory. It’s giving birth to millions of new stars in a ring outside its core. New stars are also taking shape in M63. Its arms aren’t sharp and well defined like those of the other galaxies, though. Instead, they look like strings of cotton balls. M106 is the largest of the quadrant’s bright galaxies — wider than the Milky Way. A supermassive black hole sits at its heart. It’s encircled by a disk of hot gas. Radiation from the gas sets off a chain of events that produces an extra set of spiral arms, which wrap above the galaxy’s bright disk. Canes Venatici is in the east-northeast as night falls, to the right and lower right of the Big Dipper. All four of its prominent galaxies are visible through small telescopes.   Script by Damond Benningfield

Natural Sciences
Published: April 5, 2020, 5 a.m.

Moon and Regulus

Regulus, the bright heart of Leo, the lion, shines close to the right or upper right of the Moon as night falls this evening. And it’ll be to the lower right of the Moon as they set, a couple of hours before sunrise. Because it was the brightest member of a prominent constellation, Regulus played a major role in the astronomy and skylore of many cultures. And they gave it names to match. In fact, the name “Regulus” means “the little king.” The name was bestowed by Nicolaus Copernicus, the 16th-century astronomer who showed that Earth orbits the Sun, not the other way around. He adapted the name from an earlier one, Rex, which means “the king.” Less than a century after Copernicus came up with Regulus, German astronomer Johann Bayer devised another name that’s also still in common use: Alpha Leonis, indicating that it’s the brightest or most important star of Leo. Bayer labeled more than 1500 stars. He used a letter of the Greek alphabet followed by the name of the star’s constellation. “Alpha” usually was applied to the constellation’s brightest star, but not always. Sometimes, Bayer labeled the stars based on their location, not their brightness. Regulus qualifies as the “alpha” star both ways. Not only is it the lion’s leading light, but it’s also at the bottom of a pattern that outlines the lion’s head and mane. So this “royal” star is the most prominent member of a royal constellation: Leo, the king of the beasts.   Script by Damond Benningfield

Natural Sciences
Published: April 4, 2020, 5 a.m.

Venus and the Pleiades

Two of the great beauties of the night sky, Venus and the Pleiades, will slide past each other the next few nights. Venus is the brilliant “evening star,” high in the west at nightfall. The Pleiades is a star cluster that forms a tiny dipper. It’s above Venus this evening. But Venus will stand directly beside the cluster’s brightest star tomorrow night. Astronomers can tell you the distance to Venus to within a few miles. But the Pleiades is another story. Different studies over the last couple of decades, using different techniques and equipment, have yielded estimates that vary by about 50 light-years. For a long time, most estimates said the distance was about 440 light-years. But a space telescope designed to make the most accurate measurements up to that time disagreed. It came up with a distance of only 390 light-years. Astronomers recalibrated the satellite’s observations a few years later and came up with a slightly greater distance. A new and more accurate space telescope is measuring stellar distances even now. Its early look at the Pleiades puts the cluster back in the range of 440 light-years — just as it was before space telescopes. The difference doesn’t mean much to casual skywatchers. But it’s crucial to astronomers. They use clusters like the Pleiades to study how stars evolve. To do so, they need to know how far away the stars are, which reveals how bright they are — a key measurement in understanding the stars.   Script by Damond Benningfield

Natural Sciences
Published: April 3, 2020, 5 a.m.

Bright Subject

Until 1845, almost no one had seen the Sun as anything other than a bright disk in the daytime sky. A few astronomers had looked at it with special telescopes, or traced its projected image on a piece of paper. But that was about it. That changed 175 years ago today, when two French scientists snapped the first large photograph of the Sun. It was published in a book about astronomy, and later in other places — giving the world a close-up look at our star. Armand Fizeau and Leon Foucault were young scientists fresh out of college. They were interested in the daguerreotype process — the first successful technique for taking photographs. It involved coating a copper plate with light-sensitive chemicals, exposing the plate, then using other chemicals to reveal the image. Fizeau and Foucault refined the technique, then snapped a series of pictures of the Sun. Those images were tiny, though — the Sun was only about half an inch across — so they revealed almost no detail. But on April 2nd of 1845, they took a much larger picture — the Sun measured about four and a half inches across. It showed two groups of sunspots, as well as some of the “bumpiness” on the Sun’s surface. Fizeau and Foucault each spent a lot more time studying the Sun. And each of them used their observations to calculate the speed of light. They came up with numbers that were within a few percent of the true value — all from watching the Sun.   Script by Damond Benningfield

Natural Sciences
Published: April 2, 2020, 5 a.m.

Volcanic Exomoon

A possible moon in a distant star system wouldn’t be a good place for an evening stroll. If astronomers are right, its surface is covered with molten rock, and giant volcanoes belch hot gas out into space. The moon is in a system known as WASP-49, which is about 550 light-years away. The central star is about the same size, mass, and temperature as the Sun. The star is orbited by a planet that’s as big as Jupiter, the giant of our own solar system, but only a third of Jupiter’s mass. It’s so puffed up in part because it’s quite close to the star — far closer than any of the planets in our own solar system. Those details about the system are pretty well established. The moon, on the other hand, hasn’t been confirmed. Its existence is based on circumstantial evidence. That evidence includes a “doughnut” of sodium and potassium around the planet. A team of European researchers concluded that the material is too far out to come from the planet itself. Instead, they reported, it’s probably pumped into space by volcanoes on a hot moon. Finding moons in other star systems is hard, though. Astronomers have discovered a couple of candidates, but not one has been confirmed. So it could take a while to confirm the presence of this possible moon. Incidentally, the system is in Lepus, the hare, which is below the feet of Orion. WASP-49 is low in the southwest at nightfall. It’s far too faint, though, to see without a telescope.   Script by Damond Benningfield

Natural Sciences
Published: April 1, 2020, 5 a.m.

Hardy Planet

A giant planet that’s orbiting a dead star is tough. It survived the star’s demise — a process that sent big blobs of hot gas flying out into space. And it’ll probably survive being eroded away by the star’s hot corpse. The planet orbits a white dwarf — the remnant of a once “normal” star. As the star died, it expelled its outer layers into space, leaving only its hot core. The core is more than half as massive as the Sun, but only about one percent as wide — about the size of Earth. Astronomers in Europe discovered a disk of gas and dust around the white dwarf. From the size and composition of the disk, they concluded that it’s being fed by a planet. It’s the first planet known to orbit a white dwarf. The planet is several times the size of the white dwarf. That makes it about as big as Uranus or Neptune, two of the giants of our own solar system. But radiation from the white dwarf is blasting away the planet’s outer layers — at 3,000 tons per second. Much of the debris spirals toward the star, forming the disk. The researchers say the planet should survive the stellar blowtorch, though. It’ll lose only a small fraction of its mass. It will continue to orbit the dead star as it slowly cools and fades into the long cosmic night. The system is about 2,000 light-years away. It’s in Cancer, the crab, which is high overhead as night falls. It’s far too faint, though, to see without a telescope. We’ll talk about a hot moon tomorrow. Script by Damond Benningfield

Natural Sciences
Published: March 31, 2020, 5 a.m.

Mars and Saturn

The planets Mars and Saturn don’t have a lot in common. Mars is small, dense, and rocky. Saturn probably has a rocky core, but most of it is made up of gas. So while Saturn is many times larger than Mars, it’s the “fluffiest” planet in the solar system. One possible similarity, though, is rings. Saturn is encircled by wide, beautiful rings. Mars doesn’t have any rings today, but it could have had them in the distant past — and might again millions of years in the future. Saturn’s rings probably formed when a small moon was pulverized. The moon might have passed too close to Saturn and was pulled apart by Saturn’s gravity. Or it might have been shattered by a collision with another body. Mars could have been smacked by a smaller object billions of years ago, creating its own rings. Some of that debris might have coalesced to form the planet’s moons, Phobos and Deimos. Phobos is only 3700 miles above the Martian surface. And it’s sliding closer — by about six feet per century. In 50 million years or so, it’ll either crash into Mars, or be pulled apart by the planet’s gravity — creating a new ring. Mars and Saturn are forming a tight pair in the early morning sky. They’re low in the southeast at first light, to the lower left of brilliant Jupiter. Tomorrow, Mars will stand a little below Saturn. After that, Mars will slide away from Saturn. In a few days, that’ll break up the pairing of these quite-different siblings. Script by Damond Benningfield

Natural Sciences
Published: March 30, 2020, 5 a.m.

Arneb

With every breath, you’re inhaling the “ash” from a nuclear furnace — nitrogen and oxygen created by a star. Many stars are making more of these elements today, and will someday expel them into space — perhaps to fill the skies of future planets. One star that’s made a lot of nitrogen is Arneb, the leading light of the constellation Lepus, the hare. It’s in the southwest as night falls, below brilliant Orion. Arneb is roughly 14 times the mass of the Sun. Such heavy stars “burn” through the hydrogen fuel in their cores in a hurry. They smash together the hydrogen to make helium. But they do it in a different way from stars like the Sun. The Sun makes helium directly by fusing the nuclei of hydrogen atoms — bare protons. But stars like Arneb use a catalyst: carbon, which is present in small amounts when the star is born. In a series of steps, the carbon fuses with hydrogen to make nitrogen, followed by a heavier form of carbon. This carbon then splits apart. That yields helium plus the type of carbon that started the whole thing. So hydrogen is converted to helium, while the carbon is still around to continue the process. In Arneb, some of the nitrogen created in this sequence has survived. It’s mixed with the star’s outer layers. Arneb eventually will blast the nitrogen and other elements created inside the star out into space. That will seed the galaxy with the ingredients for new stars, planets — and planetary atmospheres.   Script by Damond Benningfield

Natural Sciences
Published: March 29, 2020, 5 a.m.

Moon and Venus

The clouds of Venus are especially bright. They reflect about two-thirds of the sunlight that strikes them. That makes Venus a brilliant target in our night sky. Yet there are dark sheets inside the clouds. They absorb ultraviolet energy from the Sun. They could be caused by volcanoes. But it’s also possible they could be big “mats” of bacteria — perhaps the survivors of a once-thriving planet. Today, the surface of Venus is decidedly un-friendly. The temperature is 865 degrees, the “air” is made of carbon dioxide, and the pressure is equal to a depth of two-thirds of a mile in Earth’s oceans. No Earthly organisms could survive those harsh conditions. Yet some Earthly bacteria could survive about 30 to 40 miles above Venus’s surface. Temperatures and pressures are similar to those at Earth’s surface. And the clouds are made of sulfuric acid — a source of chemical energy to help sustain the bacteria. It’s possible that Venus was comfortable for billions of years. That could have been enough time for life to evolve — then move to the clouds when conditions got worse, No Venus-orbiting spacecraft has had the ability to measure the composition of the dark regions in the clouds. But future missions might target them — perhaps telling us if anything is living on our sister world. And Venus teams with the crescent Moon to put on a great show this evening. They’re well up in the sky at nightfall, and don’t set until shortly before midnight. Script by Damond Benningfield

Natural Sciences
Published: March 28, 2020, 5 a.m.

Wilhelm Roentgen

It’s not unusual for a husband to take a picture of his wife displaying her wedding ring. Until Wilhelm Roentgen came along, though, none had taken a picture of not just the ring, but of the bones beneath it. Roentgen had just discovered X-rays — a form of light that can pass right through many substances, including human flesh. The shot of his wife’s hand — including her ring — was the first X-ray image. Roentgen was born 175 years ago today, in Germany. His family moved to the Netherlands when he was three. He developed an interest in the outdoors, and in building mechanical devices. But he also wanted to learn how the universe works, so he earned a PhD in physics in Switzerland. In 1895, Roentgen was studying a form of energy that’s produced when an electric charge is passed through a vacuum tube. He put his test rig inside a black box, which was in a dark room. When he set if off, though, it caused a light-sensitive screen a few feet away to glow. Roentgen decided that his equipment was producing a new form of rays. He called them X-rays, although others called them Roentgen rays. Scientists found a way to put those rays to work. Eventually, that included astronomers, who study X-rays produced by objects in the sky. The list includes the remnants of exploded stars, disks of hot gas around black holes, and clouds of gas around clusters of galaxies. The observations help astronomers “diagnose” how these objects work — thanks to X-rays.   Script by Damond Benningfield

Natural Sciences
Published: March 27, 2020, 5 a.m.

Busy Betelgeuse

Betelgeuse lost some of its luster in recent months. By early this year, the supergiant star was fainter than it had been in a long time. That dropped it not only from the top 10 brightest stars in the night sky, but from the top 20. And astronomers are trying to figure out what that means. Betelgeuse forms the shoulder of Orion the hunter. It’s high in the southwest as night falls, and shines bright orange. The star is one of the most impressive in our part of the galaxy. It’s a dozen or more times the mass of the Sun, and hundreds of times the Sun’s diameter. If it took the Sun’s place, in fact, it would engulf the four inner planets, including Earth. And it might reach all the way to the fifth planet, Jupiter. That’s the star’s average size. Betelgeuse puffs in and out like a beating heart, getting bigger and smaller with each beat — and brighter and fainter. Its recent fade, though, made it fainter than has ever been recorded with modern instruments. That led to speculation that Betelgeuse was about to explode as a supernova. And someday, it will — in the next hundred thousand years or so. Instead, Betelgeuse might have appeared so faint because it has several overlapping “beats,” and two of them reached their low points at the same time. Or perhaps the star expelled a lot of dust, creating a dense “fog” around itself. Whatever the reason, astronomers say this impressive star is likely to hang around for a long time to come.   Script by Damond Benningfield

Natural Sciences
Published: March 26, 2020, 5 a.m.

‘Windy’ Galaxies

NGC 4449 is small but busy. The dwarf galaxy looks like it’s recently merged with a couple of other galaxies. It’s forming stars at a rapid pace — star for star, much faster than in our home galaxy, the Milky Way. And it’s blowing a “wind” of hydrogen and heavier elements into the space around it. But the wind isn’t nearly as thick or as extensive as theory predicts. So the ideas about how such galaxies evolve, and how they interact with the rest of the universe, may need work. NGC 4449 was one of a dozen dwarf galaxies targeted in a recent study, led by Kristen McQuinn of Rutgers and the University of Texas. Earlier work had shown that the galaxies were giving birth to many stars. The new study looked at how much gas the galaxies were blowing out into space. Theory said they should be expelling a lot of it — the result of stellar explosions. It also predicted that the winds would contain a lot of material heavier than hydrogen and helium, the lightest elements. But while most of the galaxies are pumping out some gas, it isn’t nearly as much as expected. Much of what they are expelling could fall back in. And the chemistry isn’t right, either. So theorists have some work to do to explain the behavior of some of the smallest galaxies. NGC 4449 is in the northeast as night falls, not far from the Big Dipper. The galaxy is about 12 million light-years away. And it’s so faint that you need a telescope to see it. Script by Damond Benningfield  TODAY'S PROGRAM WAS MADE POSSIBLE BY THE NATIONAL SCIENCE FOUNDATION  

Natural Sciences
Published: March 25, 2020, 5 a.m.

Dwarf Galaxies

Our home galaxy, the Milky Way, is the hub of a galactic empire. It’s not the kind with death stars and Jedi knights, though. Instead, it’s an empire of smaller galaxies. About 50 of these “dwarf” galaxies orbit the Milky Way, held in place by its powerful gravity. As those numbers suggest, dwarf galaxies are the most common type of galaxy in the universe. They outnumber giants like the Milky Way by a wide margin. But it takes a whole mess of them to add up to much. In fact, the Milky Way is more massive than all the dwarf galaxies it commands combined. Some of these cosmic “puffballs” may have been pulled out of larger galaxies by encounters between big galaxies. But most of them probably formed in the early universe — the very first collections of stars. The galaxies were packed together tightly, so many of them began to merge. That’s probably how most of the big galaxies took shape — through mergers between the little guys. And that process continues today. We see many large galaxies gobbling up the dwarfs. That includes the Milky Way. There’s evidence that it’s consumed quite a few smaller galaxies during its long lifetime. And astronomers have discovered one galaxy that’s being consumed by the Milky Way now, and others that were pulled in fairly recently. All of them will lose their galactic identity — their stars pulled away from them by the mighty Milky Way. We’ll have more about dwarf galaxies tomorrow. Script by Damond Benningfield

Natural Sciences
Published: March 24, 2020, 5 a.m.

Towering Venus

The planet Venus is at its towering best right now. The “evening star” is high in the west at sunset — just about as high up as it ever gets. And it doesn’t set until 11 or 12, providing plenty of time to watch it. Venus is the second planet from the Sun, while Earth is the third planet. So as seen from Earth, Venus never strays very far from the Sun. It’s visible for up to a few hours before sunrise or after sunset, but no more — it can’t remain in the sky all night, as some of the other planets do. And for the next few days, it’s at its greatest extension from the Sun — about 46 degrees. Its path across the sky is tilted a bit, though, so it doesn’t stand quite that high above the horizon as the Sun sets. Still, this is just about as high in the evening sky as you’ll ever see it. Because of the giant gap between Sun and Venus, this is a good time to look for the planet during daylight. It’s bright enough to see without any help — no binoculars or telescope are needed. It’s tough to pick out against the blue sky, though. But once you find it, it’s pretty easy to go back to. A couple of hours before sunset, for example, Venus is high in the southwest. It’s to the upper left of the Sun, by about four and a half times the width of your fist at arm’s length. If you can’t find it, though, no worries. Venus will be plenty bright once the Sun sets, and will remain in view until almost midnight — a long performance for the “evening star.”   Script by Damond Benningfield

Natural Sciences
Published: March 23, 2020, 5 a.m.

Cor Caroli

Several bright stars are identified as “hearts.” Regulus, for example, is the heart of the celestial lion, while Antares is the heart of the scorpion. One of the few whose name actually means “the heart” is in good view on spring evenings. Cor Caroli is the brightest star of Canes Venatici, the hunting dogs. It’s in the east as night falls, to the right of the tip of the Big Dipper’s handle. But the star’s name doesn’t refer to its constellation. Instead, Cor Caroli means “Heart of Charles.” It was named in the 1600s, and it refers to either England’s King Charles I, or his son, Charles II. Perhaps fittingly, Cor Caroli consists of two stars. One of them is a good bit bigger and heavier than the Sun, and a hundred times brighter. The other also outdoes the Sun, although it’s not as impressive as its sibling. The brighter star is the prototype of an entire class of stars. They get brighter and fainter over a period of a few days. The change probably is caused by starspots — giant magnetic storms on the star’s surface. They’re darker than the surrounding gas. So as they rotate into view, the star’s overall brightness goes down a bit. The storms are driven by the star’s high-speed rotation. Despite its great size, it spins once every five-and-a-half days, versus about once a month for the Sun. That stirs up the star’s outer layers of gas, creating a powerful magnetic field — and giving Charles a “stormy” heart.   Script by Damond Benningfield

Natural Sciences
Published: March 22, 2020, 5 a.m.

The Camel Leopard

You might expect a constellation that bears the names of three different animals to be a bold one. Unfortunately, though, Camelopardalis isn’t. It is one of the largest constellations, covering a large wedge of the northern sky. But it just isn’t very bold. All of its stars are so faint that you have to get away from city lights to see them. A literal translation of “Camelopardalis” is “the camel leopard.” And one astronomer who wrote about it soon after its creation in the early 1600s said that it was a camel. But the writer was a bit confused. That’s because “Camelopardalis” is a form of the Latin word for “giraffe” — a creature that appears to combine the long neck of the camel with the spots of the leopard. For the casual skywatcher, the semantics probably are more interesting than the constellation itself. Its brightest star is only fourth magnitude — not bright enough to see from a light-polluted city, or even most suburbs. The star is almost 900 light-years away. So the fact that it’s visible from any place on Earth with the unaided eye tells us that it’s quite impressive. It’s several times heavier than the Sun, and about 1500 times brighter — the brightest “spot” of the camel-leopard. At this time of year, Camelopardalis is to the upper left of the North Star as darkness falls, so it’s in fine view. It wheels below the North Star later on, and is low above the northern horizon at first light. Script by Damond Benningfield

Natural Sciences
Published: March 21, 2020, 5 a.m.

Counting Candles

There are many ways to count the candles on a star’s birthday cake. Two star clusters that are in the western evening sky at this time of year provide two examples. Messier 34 is in the constellation Perseus. It’s about half way up the sky in the west-northwest at nightfall — well to the upper right of Venus, the “evening star.” And Messier 36 is higher in the sky, in Auriga. It’s to the left of the yellow-orange star Capella. M36 is the younger of the two clusters — less than 25 million years old. One way astronomers came up with that number is by measuring lithium in especially small, cool stars. Stars begin life with just a smattering of lithium. And it’s quickly destroyed by the star’s nuclear reactions. More-massive stars “burn” through their lithium faster than less-massive stars. So by measuring the amount of the element in stars of different weights, they can come up with an estimate of a cluster’s age — in this case, about 22 million years. Astronomers used stars at the opposite end of the age scale to measure the age of M34. They used white dwarfs — the small, dead cores of once-normal stars. Stars of different masses burn out at different times, with heavier stars going first. And they leave white dwarfs that have different mixtures of chemical elements. The white dwarfs in M34 indicate an age of about 225 million years — a good match to the other techniques used to count a star’s birthday candles.   Script by Damond Benningfield

Natural Sciences
Published: March 20, 2020, 5 a.m.

Spring Equinox

Lots of folks are likely to end up with egg on their faces today — or at least on their kitchen counters. That’s because they’ll be checking out a seasonal myth. It says that you can balance a raw egg on its end on the equinoxes — but not on any other day. And today is the vernal equinox here in the northern hemisphere — the beginning of spring. The myth is usually tied to the spring equinox, not fall. Perhaps that’s because of spring’s association with life and rebirth, which often are represented by the egg. Here’s the basic outline of the story. At the equinox, Earth’s axis is perpendicular to the line to the Sun. That creates a special gravitational “balance” that doesn’t exist at other times of the year. This balance allows you to stand a raw egg on its end — a feat that can’t be achieved on any other date. That’s not true at all. There’s no difference in the “balance” between Earth and the Sun than at any other time of year. It’s easy to check it out by trying to stand an egg on end on different days of the year. The egg doesn’t want to cooperate, but with a little patience it can be done. It’s easier to accomplish if the egg has a rough shell and it’s sitting on a rough surface. But many people have accomplished the feat with smooth eggs on smooth surfaces. Just keep trying, and eventually you’ll get the egg-xact formula — on the equinox or any other day of the year. Tomorrow: counting birthday candles in star clusters.   Script by Damond Benningfield

Natural Sciences
Published: March 19, 2020, 5 a.m.

Making Glass

One of the treasures from the tomb of King Tutankhamen is an elaborate pectoral — a piece of jewelry worn on his chest that honored the Sun god. It’s made of gold inlaid with turquoise and other colorful stones. And its centerpiece is a scarab beetle made of golden glass — a symbol of the Sun god, and of the cycle of life.  The glass formed in the Sahara Desert about 29 million years ago. And a recent study says it was the result of an impact by a big space rock. Scientists have debated the origin of Libyan Desert Glass for decades. Some studies have suggested it formed when a space rock exploded above the surface. The resulting heat melted the desert sand, creating slabs of glass that were blasted across many square miles. But the new study, by researchers in Australia, says the meteoroid made it all the way to the ground. The impact melted the sand, just as an airburst would have. An impact, though, created more powerful shock waves, which rippled through the melted glass. That converted grains of zircon to a mineral known as reidite. Over time, that mineral reverted to zircon. But it left a “fingerprint” in the zircon, which the researchers discovered. At least a couple of big space rocks are known to have exploded in the atmosphere in the last century-plus, supporting the idea of an airburst over the Sahara. The new research, though, suggests that such outbursts might be less common -- and less of a threat to life -- and to desert sands. Script by Damond Benningfield

Natural Sciences
Published: March 18, 2020, 5 a.m.

More Moon and Planets

Mars is only half the diameter of Earth. Because it has no oceans, though, the planet has just as much land area as Earth does. That’s a lot of territory to explore — and perhaps to colonize. And there’s a lot to see there — including some of the most dramatic features in the entire solar system. One of those features is a network of canyons that dwarfs the Grand Canyon. It’s known as Valles Marineris — Mariner’s Valleys. It’s named for the Mariner 9 spacecraft, which studied the feature from orbit. Valles Marineris is more than 2500 miles long — almost as long as the distance from Seattle to Miami. It’s up to four miles deep, and 125 miles wide — so wide that if you stood on one rim, you couldn’t see the other. Mars also is home to the most impressive mountain in the solar system. Olympus Mons — Mount Olympus — is three times taller than Mount Everest. And its base covers an area bigger than New Mexico. It’s a volcano that’s been active within the last few million years — and might not be completely dead even today. No spacecraft has yet visited either of these features — in part because the landscape is so rugged. But they’re important targets for science — and perhaps the site of adventures for future colonists. Mars is one of two planets that huddles near the Moon at dawn tomorrow. Jupiter is the brighter of the two, with Mars just a whisker away. And a third planet, Saturn, is close to their lower left.   Script by Damond Benningfield

Natural Sciences
Published: March 17, 2020, 5 a.m.

Jumpy Stars

The celestial great bear is light on his feet. His paws are represented by three pairs of stars. And all three pairs have names that mean “leap” or “spring.” The stars of the bear’s hind leg are known as Alula Borealis and Alula Australis. “Alula” is from an Arabic phrase that means “the first leap of the gazelle.” The other pairs of stars represent the second and third leaps. Alula Borealis — the northern member of the pair — is the brighter of the two stars. It’s a giant star that’s passed the end of its “normal” lifetime. It’s going through a series of changes in its core. Those changes have caused the star’s outer layers to puff up like a giant balloon. The star is almost 60 times the Sun’s diameter, and almost 800 times its total brightness. That makes it easy to see even though it’s 400 light-years away. Alula Australis — the southern star — is only about 30 light-years away. It actually consists of four stars, which are split into two pairs. The leading light of each pair is similar to the Sun. The two companion stars are much smaller and fainter than the Sun, so they don’t add much to the system’s brightness. Alula Borealis and Australis are bright enough to see with the unaided eye, although not from light-polluted cities. At nightfall, they’re well to the right of the bowl of the Big Dipper — the bear’s body. They’ll rotate high above the dipper during the night, and stand to its lower left at first light tomorrow. Script by Damond Benningfield

Natural Sciences
Published: March 15, 2020, 5 a.m.

Moon and Antares

Before astronauts landed on the Moon, space artists often depicted the lunar mountains and craters as harsh and jagged. The reality turned out to be less dramatic, though. Mountains and crater rims tend to be soft and rounded — far more subdued than most of the similar features here on Earth. The reason is a process called space weathering. It works like the weathering here on Earth, where wind and rain erode geologic features. On the Moon, though, the weathering is produced by the solar wind and a “rain” of space rocks. The Moon has almost no atmosphere to protect it from the rest of the universe. As a result, it faces a non-stop bombardment from outside. The solar wind, for example, is a high-speed flow of charged particles from the Sun. As the particles hit the surface, some are embedded in grains of the lunar “dirt,” known as regolith. Among other things, that can create molecules of a compound that’s similar to water. Space rocks produce more obvious effects. Big ones gouge big impact craters, and blast debris all across the Moon. But the Moon is hit by billions of tiny space rocks as well. Across billions of years, that non-stop rain has pulverized much of the surface, creating the powdery regolith. And it’s helped wear down the lunar mountains and craters — giving them a gentle profile. Look for the Moon before and during dawn tomorrow. Antares, the bright orange heart of the scorpion, is close to its lower right.   Script by Damond Benningfield

Natural Sciences
Published: March 14, 2020, 5 a.m.

Mintaka

It’s hard to think of a star that’s more than eight times the mass of the Sun as puny. But that’s the case for the least-massive star of Mintaka, which forms the right end of Orion’s Belt. Mintaka consists of at least three stars, and perhaps more. The stars are all fairly close together. Two of them, in fact, are so close that they orbit each other once every six days. The puny star is a member of that close pair. Its bigger companion probably is a couple of dozen times the Sun’s mass, and almost 200 thousand times the Sun’s brightness. The more distant member of the trio is only slightly less impressive. All three stars are “burning” the nuclear fuel in their cores at a furious rate. As a result, they’ll live much shorter lives than stars like the Sun — millions or tens of millions of years, versus 10 billion years for the Sun. The heavier stars will burn out first. And when they do, they’ll end their lives as supernovae — titanic explosions that briefly outshine billions of normal stars. The puny star appears to be on the dividing line between a supernova and a less-violent demise, so its fate is uncertain. The stars are all “fusing” lighter elements in their cores to make heavier ones. When they die, those elements will be expelled into space. In the distant future, they could be incorporated into new stars, planets — and perhaps living organisms. The same fate awaits the other stars of Orion’s Belt — big stars with bigger futures.   Script by Damond Benningfield

Natural Sciences
Published: March 13, 2020, 5 a.m.

Alnilam

The stars of Orion’s Belt are really superstars. All three of them are among the biggest, heaviest, and brightest stars in the entire galaxy. And the star at the middle of the belt could be the most impressive of the three. Alnilam is at least 30 times the mass of the Sun, and 275,000 times brighter. But it could be twice as massive as that, and three times as bright. The wiggle room is caused by uncertainty in the star’s distance. Most research says it’s about 1350 light-years away. But a second look at measurements made by a space telescope put the distance at almost two thousand light-years. The farther away the star is, the bigger and brighter it is. Regardless of the distance, there’s no doubt that Alnilam and the other stars of the belt are monsters. Because of their great heft, they’re “fusing” the elements in their cores at a furious rate. That creates enormous amounts of energy — the reason the stars are so bright. That also creates a plethora of chemical elements, as lighter elements fuse together to make heavier ones. When the stars die, they’ll expel many of those elements into space, providing the raw materials for new stars and planets; we’ll have more about that tomorrow. In the meantime, look for Orion’s Belt in the south-southwest as night falls, and dropping down the southwestern sky later on. The belt is a short line of three moderately bright stars. Orion's brightest stars line up above and below the belt.   Script by Damond Benningfield

Natural Sciences
Published: March 12, 2020, 5 a.m.

Alnitak

Orion’s Belt is one of the best-known star patterns in the night sky — and one of the easiest to find. It’s a short line of three fairly bright stars. Right now, it’s in the south-southwest as night falls, with Orion’s other bright stars above and below it. The star at the left end of the belt is Alnitak. The system includes two supergiants — among the biggest, brightest, and heaviest stars in the galaxy. The main star is more than 30 times the mass of the Sun, and 250,000 times brighter. The second star is less impressive, but still a monster. Alnitak and Orion’s other bright stars were born from a huge complex of gas and dust. Deep images of the area around Alnitak reveal several clouds of this material — some of which is coalescing to make more stars. There are a couple of ideas for how this complex of stars took shape. One says the formation of one group of stars triggered the formation of the next group. In this scenario, there are four main groups. The first took shape to the north of Orion’s Belt. The stars of the belt are in the second group, so they’re all the same age — roughly six million to eight million years. And the youngest stars are below the belt. The other idea says the stars were all born in the same region, but are streaming away from their birthplace. We’re looking down the streamer, with the youngest stars closest to us. Either way, the stars of Orion’s Belt are young and vigorous — and we’ll have more about that tomorrow.   Script by Damond Benningfield

Natural Sciences
Published: March 11, 2020, 5 a.m.

Osiris

Orion’s Belt is one of the easiest star patterns to recognize. It’s a line of three moderately bright stars, with a slight dip at the left end. From most of the United States, it’s about half way up the southern sky as darkness falls at this time of year. Not surprisingly, this lineup of stars has played a big role in the skylore and mythology of many cultures. In China, for example, the belt formed one of the 28 lunar mansions — the Chinese constellations. Perhaps the most famous bit of mythology comes from ancient Egypt. There, the stars were associated with Osiris, the god of the underworld. They were considered his eternal resting place. By the time the pyramids of Giza were built, the pharaoh was considered a god as well. When he died, he joined with Osiris in this same group of stars. In fact, the first and largest pyramid at Giza, built by the pharaoh Khufu, appears to align with those stars. A shaft from the pyramid’s main chamber aims toward the location of Orion’s Belt at the time of construction — 4500 years ago. The shaft might have been a sort of pathway to heaven for the dead king — a way for him to unite with Osiris in the afterlife. Some have even suggested that the pyramids were laid out in a way that mirrors the belt — although most experts disagree. Regardless of that alignment, though, there’s little doubt that the god Osiris was linked to the stars of Orion’s Belt. We’ll have more about the belt tomorrow.   Script by Damond Benningfield

Natural Sciences
Published: March 10, 2020, 5 a.m.

Bright Beacon

The North Star, Polaris, has served as a beacon for centuries. Its constant position in the night sky allows navigators to plot their latitude north of the equator. For truly long-range travel, though, the beacon of choice is Canopus, the second-brightest star in the night sky. If you live south of about Dallas, it’s in view on winter nights, well below Sirius, the night sky’s brightest star. Right now, it’s due south in early evening, just above the horizon. Considering its heritage, perhaps it’s not surprising that Canopus is associated with navigation. It’s the brightest star of the ancient constellation Argo Navis — the ship that carried Jason and the Argonauts. And the name “Canopus” may come from the pilot of another mythological ship, which rescued Helen of Troy. The star was a beacon to the sailors of Polynesia, among others, who used its light to guide them from island to island. In modern times, Canopus has guided spacecraft to the Moon and other planets. It’s bright and it’s far away from the Sun’s path across the sky, so a craft can use Canopus and the Sun to triangulate its position. Canopus has even played a role in navigating to the stars. It was home to the planet Arrakis in the novel “Dune.” The planet contained the only supply of “spice.” Consuming a lot of it gave the user the ability to navigate between the stars. So stellar navigation was made possible by Canopus — a star that helps modern-day navigators sail to other worlds.   Script by Damond Benningfield

Natural Sciences
Published: March 9, 2020, 5 a.m.

Seeing Stars

Some of the brightest stars in the night sky are visible on these late-spring evenings. There’s Sirius, the brightest of them all, high in the south at nightfall. Orion is off to its upper right. And stars like Regulus, near the Moon, and Aldebaran, near Orion, add to the lightshow. You might wonder how many stars you can see in the night sky in all. The answer: it depends. It depends on how dark your sky is, for example. If you have a clear, moonless night, and you can get away from city lights, the number goes way up. Good eyesight helps, too. Under perfect conditions, most experts say the human eye might be able to see almost 10,000 individual stars. That covers the entire sky. Practically, of course, we see only half of the sky at any moment. So the top number visible at any given time is fewer than 5,000. As the viewing conditions change, though, the numbers drop dramatically. A full Moon, like we have tonight, casts a bright glare that overpowers most of the stars. Artificial lights add their own glare. And dust and other junk in the air dim the view even more. So from the suburbs, your view might be limited to a few hundred stars at a time. And from the center of a city, it might be no more than a few dozen. But there are a few tips for improving the view. Get away from streetlamps and other lights, and give your eyes a few minutes to get used to the darkness. Then enjoy the stars — no matter how many you can see.   Script by Damond Benningfield

Natural Sciences
Published: March 8, 2020, 6 a.m.

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