Natural Sciences Podcasts: Best Episodes & Shows of 2020

The Best Natural Sciences Episodes for August 2020

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  StarDate Podcast

  Short-Night Moon

  The Moon is full tonight — a brilliant light for the holiday night. Yet it won’t be in view all that long. It’s the Short-Night Moon — the full Moon that’s in sight for a shorter period than any other full Moon of the year. We see so little of tonight’s Moon because the Sun and the full Moon are like two people on a seesaw — when one is up, the other is down. At this time of year, near the summer solstice, the Sun is “up.” It’s in view for a long time, and it climbs highest across the sky. That means the Moon, at the other end of the seesaw, is “down.” It stays low as it scoots across the sky, and it’s not in view for long. From Tampa, for example, the Sun will be in the sky for almost 14 hours, with the Moon in view for only 10 and a half hours. From Dallas, it’s more than 14 hours of sunlight, followed by just 10 hours of moonlight. And from Spokane, which is much farther north, the Sun is in view for almost twice as long as the Moon — almost 16 hours versus just eight and a half. Most years, the Short-Night Moon is in June. This year, though, tonight’s full Moon is closer to the solstice than the one in June, so July takes the honors. And the Moon is followed across the sky tonight by two short-night planets. Bright Jupiter is to the lower left of the Moon in early evening, with fainter Saturn to the lower left of Jupiter. The three worlds will be much closer together tomorrow night; more about that tomorrow.   Script by Damond Benningfield

  The Moon is full tonight — a brilliant light for the holiday night. Yet it won’t be in view all that long. It’s the Short-Night Moon — the full Moon that’s in sight for a shorter period than any other full Moon of the year. We see so little of tonight’s Moon because the Sun and the full Moon are like two people on a seesaw — when one is up, the other is down. At this time of year, near the summer solstice, the Sun is “up.” It’s in view for a long time, and it climbs highest across the sky. That means the Moon, at the other end of the seesaw, is “down.” It stays low as it scoots across the sky, and it’s not in view for long. From Tampa, for example, the Sun will be in the sky for almost 14 hours, with the Moon in view for only 10 and a half hours. From Dallas, it’s more than 14 hours of sunlight, followed by just 10 hours of moonlight. And from Spokane, which is much farther north, the Sun is in view for almost twice as long as the Moon — almost 16 hours versus just eight and a half. Most years, the Short-Night Moon is in June. This year, though, tonight’s full Moon is closer to the solstice than the one in June, so July takes the honors. And the Moon is followed across the sky tonight by two short-night planets. Bright Jupiter is to the lower left of the Moon in early evening, with fainter Saturn to the lower left of Jupiter. The three worlds will be much closer together tomorrow night; more about that tomorrow.   Script by Damond Benningfield

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  StarDate Podcast

  Mount St. Helens

  As the Sun rose on May 18th of 1980, Mount St. Helens was the fifth-tallest mountain in Washington State — almost 10,000 feet tall. By sunset, it didn’t even rank in the top 50. The volcano had staged a massive eruption. It chopped 1300 feet off its height — and blasted away one whole side of the mountain. It was one of the most powerful and destructive eruptions in American history. It killed almost 60 people, and flattened dozens of square miles of forest. It melted tons of ice and snow and sent the water roaring down rivers. And it expelled a cloud of ash that turned day to night across much of Washington. Mount St. Helens is a stratovolcano. Such peaks are the most dangerous volcanoes because they can erupt quickly and violently. They have much steeper sides than the shield volcanoes found in Hawaii. Volcanoes have been seen on several other worlds of the solar system. Most of them are shield volcanoes. There’s evidence of a few stratovolcanoes on Mars, but it’s hard to tell for sure — it’s likely that none of them has erupted in millions of years or longer. Mount St. Helens erupted a few more times in 1980, although none with the force of the initial blast. And it’s been active several more times since then — most recently in 2008. Today, it’s rated as a “very high threat” to eventually erupt again — perhaps knocking it even farther down the list of Washington’s tallest mountains.   Script by Damond Benningfield

  As the Sun rose on May 18th of 1980, Mount St. Helens was the fifth-tallest mountain in Washington State — almost 10,000 feet tall. By sunset, it didn’t even rank in the top 50. The volcano had staged a massive eruption. It chopped 1300 feet off its height — and blasted away one whole side of the mountain. It was one of the most powerful and destructive eruptions in American history. It killed almost 60 people, and flattened dozens of square miles of forest. It melted tons of ice and snow and sent the water roaring down rivers. And it expelled a cloud of ash that turned day to night across much of Washington. Mount St. Helens is a stratovolcano. Such peaks are the most dangerous volcanoes because they can erupt quickly and violently. They have much steeper sides than the shield volcanoes found in Hawaii. Volcanoes have been seen on several other worlds of the solar system. Most of them are shield volcanoes. There’s evidence of a few stratovolcanoes on Mars, but it’s hard to tell for sure — it’s likely that none of them has erupted in millions of years or longer. Mount St. Helens erupted a few more times in 1980, although none with the force of the initial blast. And it’s been active several more times since then — most recently in 2008. Today, it’s rated as a “very high threat” to eventually erupt again — perhaps knocking it even farther down the list of Washington’s tallest mountains.   Script by Damond Benningfield

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  StarDate Podcast

  Twin Jewels

  The jewel of the northern crown caps the sky tonight. It’s high in the east at nightfall, and passes overhead a few hours later. Alphecca is the brightest star of Corona Borealis, the northern crown — a semicircle of stars that looks like a tiara. Alphecca actually consists of two jewels — two stars. We see them as a single point. If we could see them individually, though, one would shine pure white, the other yellow. That’s an indication of their surface temperatures. The yellow star is about 10,000 degrees Fahrenheit — about the same as the Sun. The white star is almost twice as hot. Surface temperature is driven by nuclear reactions deep inside the star, which create energy. The energy makes its way to the surface and shines away into space. The rate of those reactions is driven by the star’s mass. Alphecca’s yellow star, for example, is a bit less massive than the Sun. Its gravity squeezes the core tightly enough to heat it to more than 20 million degrees. That’s a little cooler than the Sun’s core. As a result, the core produces a little less energy than the Sun, so the star is a little fainter and cooler than the Sun. The white star is heavier than the Sun, so its core is twice as hot as the Sun’s. So the star’s nuclear engine runs at a faster rate, producing far more energy. That makes the surface hotter, too. And it makes the star shine far brighter than the Sun — lighting up the jewel of the northern crown.   Script by Damond Benningfield

  The jewel of the northern crown caps the sky tonight. It’s high in the east at nightfall, and passes overhead a few hours later. Alphecca is the brightest star of Corona Borealis, the northern crown — a semicircle of stars that looks like a tiara. Alphecca actually consists of two jewels — two stars. We see them as a single point. If we could see them individually, though, one would shine pure white, the other yellow. That’s an indication of their surface temperatures. The yellow star is about 10,000 degrees Fahrenheit — about the same as the Sun. The white star is almost twice as hot. Surface temperature is driven by nuclear reactions deep inside the star, which create energy. The energy makes its way to the surface and shines away into space. The rate of those reactions is driven by the star’s mass. Alphecca’s yellow star, for example, is a bit less massive than the Sun. Its gravity squeezes the core tightly enough to heat it to more than 20 million degrees. That’s a little cooler than the Sun’s core. As a result, the core produces a little less energy than the Sun, so the star is a little fainter and cooler than the Sun. The white star is heavier than the Sun, so its core is twice as hot as the Sun’s. So the star’s nuclear engine runs at a faster rate, producing far more energy. That makes the surface hotter, too. And it makes the star shine far brighter than the Sun — lighting up the jewel of the northern crown.   Script by Damond Benningfield

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  StarDate Podcast

  Omega Centauri

  The biggest ball of stars in the Milky Way Galaxy creeps low across the south on June evenings. But it might not have been born in the galaxy. Instead, it may be the core of a smaller galaxy that was grabbed by the Milky Way billions of years ago. Omega Centauri is classified as a globular cluster. It’s the biggest and brightest in the galaxy. It contains about 10 million stars. They’re all packed into a ball that’s about 150 light-years in diameter. In the cluster’s core, stars may be just a tenth of a light-year apart. By comparison, the Sun’s closest neighbors are more than four light-years away. Several lines of evidence support the idea that Omega Centauri was born in another galaxy. For one thing, its orbit around the center of the Milky Way is backwards from the general flow. For another, its chemistry doesn’t quite match that of the Milky Way’s other stars. So it seems likely that the cluster was the core of a dwarf galaxy that passed close to the Milky Way. The Milky Way’s gravity grabbed the smaller galaxy and pulled it in. The stars in the galaxy’s outer regions were absorbed into the body of the Milky Way. But the core stuck together – forming a bright globular cluster. Omega Centauri is quite low in the south as night falls. From the northern third of the United States, in fact, it’s below the horizon, so it’s not visible at all. From other locations, it looks like a faint, fuzzy star – the remnant of a galaxy. Script by Damond Benningfield

  The biggest ball of stars in the Milky Way Galaxy creeps low across the south on June evenings. But it might not have been born in the galaxy. Instead, it may be the core of a smaller galaxy that was grabbed by the Milky Way billions of years ago. Omega Centauri is classified as a globular cluster. It’s the biggest and brightest in the galaxy. It contains about 10 million stars. They’re all packed into a ball that’s about 150 light-years in diameter. In the cluster’s core, stars may be just a tenth of a light-year apart. By comparison, the Sun’s closest neighbors are more than four light-years away. Several lines of evidence support the idea that Omega Centauri was born in another galaxy. For one thing, its orbit around the center of the Milky Way is backwards from the general flow. For another, its chemistry doesn’t quite match that of the Milky Way’s other stars. So it seems likely that the cluster was the core of a dwarf galaxy that passed close to the Milky Way. The Milky Way’s gravity grabbed the smaller galaxy and pulled it in. The stars in the galaxy’s outer regions were absorbed into the body of the Milky Way. But the core stuck together – forming a bright globular cluster. Omega Centauri is quite low in the south as night falls. From the northern third of the United States, in fact, it’s below the horizon, so it’s not visible at all. From other locations, it looks like a faint, fuzzy star – the remnant of a galaxy. Script by Damond Benningfield

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  StarDate Podcast

  Deadly Sun

  Storms on the Sun can have unpleasant consequences. They can damage satellites, force airlines to reroute flights, and even cause power blackouts. And for some marine mammals, they could be deadly. Dolphins and whales occasionally strand themselves on the beach. Biologists say there are many possible causes: injury, disease, human-made sounds, and others. And in recent years, they’ve even found a possible link between strandings and solar activity. Dolphins and whales may use Earth’s magnetic field to navigate. Solar storms can change the contours of the field. So researchers have suggested the storms may “scramble” the navigation system – like passing a bar magnet near a compass. A recent study, though, says the problem isn’t changes in the magnetic field. Instead, it may be bursts of radio waves from the storms. Researchers looked at 35 years of strandings of grey whales. They eliminated whales that were sick or injured, or that might have been confused by sonar or other loud sounds. They then compared the remaining strandings to changes in Earth’s magnetic field, and to outbursts of radio waves. The results showed no relationship between strandings and changes in the magnetic field. But there was a relationship with the radio bursts. In fact, the whales were more than four times as likely to strand during those outbursts. So storms on the Sun can be bad news for these beautiful creatures.   Script by Damond Benningfield

  Storms on the Sun can have unpleasant consequences. They can damage satellites, force airlines to reroute flights, and even cause power blackouts. And for some marine mammals, they could be deadly. Dolphins and whales occasionally strand themselves on the beach. Biologists say there are many possible causes: injury, disease, human-made sounds, and others. And in recent years, they’ve even found a possible link between strandings and solar activity. Dolphins and whales may use Earth’s magnetic field to navigate. Solar storms can change the contours of the field. So researchers have suggested the storms may “scramble” the navigation system – like passing a bar magnet near a compass. A recent study, though, says the problem isn’t changes in the magnetic field. Instead, it may be bursts of radio waves from the storms. Researchers looked at 35 years of strandings of grey whales. They eliminated whales that were sick or injured, or that might have been confused by sonar or other loud sounds. They then compared the remaining strandings to changes in Earth’s magnetic field, and to outbursts of radio waves. The results showed no relationship between strandings and changes in the magnetic field. But there was a relationship with the radio bursts. In fact, the whales were more than four times as likely to strand during those outbursts. So storms on the Sun can be bad news for these beautiful creatures.   Script by Damond Benningfield

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  StarDate Podcast

  More Moon and Mars

  Mars is a land of dust devils. Thousands of them sweep across the landscape every day — and perhaps hundreds of thousands. They’re far larger than the ones that twist across the deserts and plains on Earth. And they could be a problem for future Mars explorers. A dust devil is a twirling column of air that looks like a weak tornado. It forms under clear skies. The Sun warms the land, causing air to rise. As it rises it interacts with cooler air above, causing the column to spin. It can pick up tiny grains of sand and dust and carry them across great distances. On Earth, most dust devils are no more than a few hundred feet high, with winds equal to a good gust. On Mars, though, they can get much bigger — almost half a mile wide and about five miles high. Their top speeds are greater, too. Dust devils could be a problem for future space missions. Recent research suggests that it’s not just the wind that picks up the dust. The dust grains may create a static electric charge — like scuffing across the carpet in your socks. That charge causes some of the dust grains to “levitate” off the surface. The electric field could damage or interfere with sensitive equipment on future missions — a real “dust up” for Mars explorers. Look for Mars near the Moon early tomorrow. The planet looks like a bright orange star. It’s above the Moon as they climb into good view by 2:30 or 3, and to the upper right of the Moon at first light. Script by Damond Benningfield 

  Mars is a land of dust devils. Thousands of them sweep across the landscape every day — and perhaps hundreds of thousands. They’re far larger than the ones that twist across the deserts and plains on Earth. And they could be a problem for future Mars explorers. A dust devil is a twirling column of air that looks like a weak tornado. It forms under clear skies. The Sun warms the land, causing air to rise. As it rises it interacts with cooler air above, causing the column to spin. It can pick up tiny grains of sand and dust and carry them across great distances. On Earth, most dust devils are no more than a few hundred feet high, with winds equal to a good gust. On Mars, though, they can get much bigger — almost half a mile wide and about five miles high. Their top speeds are greater, too. Dust devils could be a problem for future space missions. Recent research suggests that it’s not just the wind that picks up the dust. The dust grains may create a static electric charge — like scuffing across the carpet in your socks. That charge causes some of the dust grains to “levitate” off the surface. The electric field could damage or interfere with sensitive equipment on future missions — a real “dust up” for Mars explorers. Look for Mars near the Moon early tomorrow. The planet looks like a bright orange star. It’s above the Moon as they climb into good view by 2:30 or 3, and to the upper right of the Moon at first light. Script by Damond Benningfield 

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  StarDate Podcast

  Centaurs

  The ancients loved creatures that were crosses between humans and something else. One of the favorites of the Greeks, for example, was the centaur. It featured the head and torso of a man combined with the body of a horse. In fact, the list of Greek constellations featured two centaurs. And both of them are still around today. Right now, one of them is dropping from view as darkness falls, while the other is climbing into view. Centaurus sits low in the south at that hour. From most of the United States, in fact, a good portion of it never climbs above the horizon. Centaurus represents Chiron, one of the gentlest and most cultured of all centaurs. He was an accomplished teacher. And he was so trusted by the gods that he was godfather to Jason and Achilles. He also served as tutor to Asclepius, the greatest healer. In the sky, Chiron is part of a larger story. He’s generally shown holding Lupus, the wolf, which is to the left of the centaur. He’s carrying it to be a sacrifice on Ara, the altar, which is below the tail of Scorpius. There’s no real story associated with the other centaur. But it’s a lot easier to see. Sagittarius is just rising in the southeast at nightfall. It climbs into good view by an hour or so later. Eight of its stars form the outline of a teapot — a pattern that’s easy to pick out. It’s highest in the sky in the wee hours of the morning, and dives toward the southwestern horizon at first light. Script by Damond Benningfield

  The ancients loved creatures that were crosses between humans and something else. One of the favorites of the Greeks, for example, was the centaur. It featured the head and torso of a man combined with the body of a horse. In fact, the list of Greek constellations featured two centaurs. And both of them are still around today. Right now, one of them is dropping from view as darkness falls, while the other is climbing into view. Centaurus sits low in the south at that hour. From most of the United States, in fact, a good portion of it never climbs above the horizon. Centaurus represents Chiron, one of the gentlest and most cultured of all centaurs. He was an accomplished teacher. And he was so trusted by the gods that he was godfather to Jason and Achilles. He also served as tutor to Asclepius, the greatest healer. In the sky, Chiron is part of a larger story. He’s generally shown holding Lupus, the wolf, which is to the left of the centaur. He’s carrying it to be a sacrifice on Ara, the altar, which is below the tail of Scorpius. There’s no real story associated with the other centaur. But it’s a lot easier to see. Sagittarius is just rising in the southeast at nightfall. It climbs into good view by an hour or so later. Eight of its stars form the outline of a teapot — a pattern that’s easy to pick out. It’s highest in the sky in the wee hours of the morning, and dives toward the southwestern horizon at first light. Script by Damond Benningfield

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  StarDate Podcast

  Alpha Centauri

  The key to a star’s appearance and lifespan is its mass. Heavier stars shine brighter but live shorter lives than less-massive ones. An example can be found in the two bright stars of Alpha Centauri, the leading light of the constellation Centaurus. It’s the closest star system to our own, at a distance of about four light-years. One of the stars is about 10 percent more massive than the Sun. The other is about 10 percent less massive than the Sun. With so little difference, you might expect them to be almost identical — but they’re not. The heavier star, Alpha Centauri A, burns through the nuclear fuel in its core faster than its companion, Alpha Centauri B. As a result, it shines three times brighter. The surface of Alpha Centauri A is also hundreds of degrees hotter, so it looks yellow-white versus the yellow-orange of Alpha Centauri B. While “A” is far brighter, “B” has a much longer future to look forward to. Its “normal” lifetime should last about half again as long as that of its companion. There’s actually a third star in the Alpha Centauri system — Proxima Centauri — that’s a long way from the other two. It’s a more extreme example of what a difference mass can make. It’s only 15 percent as massive as the Sun, so it’s only about one thousandth as bright as the Sun. Yet it will be shining a trillion years after the other two stars have faded into the cosmic night. More about Alpha Centauri tomorrow. Script by Damond Benningfield 

  The key to a star’s appearance and lifespan is its mass. Heavier stars shine brighter but live shorter lives than less-massive ones. An example can be found in the two bright stars of Alpha Centauri, the leading light of the constellation Centaurus. It’s the closest star system to our own, at a distance of about four light-years. One of the stars is about 10 percent more massive than the Sun. The other is about 10 percent less massive than the Sun. With so little difference, you might expect them to be almost identical — but they’re not. The heavier star, Alpha Centauri A, burns through the nuclear fuel in its core faster than its companion, Alpha Centauri B. As a result, it shines three times brighter. The surface of Alpha Centauri A is also hundreds of degrees hotter, so it looks yellow-white versus the yellow-orange of Alpha Centauri B. While “A” is far brighter, “B” has a much longer future to look forward to. Its “normal” lifetime should last about half again as long as that of its companion. There’s actually a third star in the Alpha Centauri system — Proxima Centauri — that’s a long way from the other two. It’s a more extreme example of what a difference mass can make. It’s only 15 percent as massive as the Sun, so it’s only about one thousandth as bright as the Sun. Yet it will be shining a trillion years after the other two stars have faded into the cosmic night. More about Alpha Centauri tomorrow. Script by Damond Benningfield 

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  StarDate Podcast

  Moon and Gemini

  Ancient skylore is pretty tawdry. Everywhere you look, you find stories of betrayal, seduction, vanity, and even murder. Yet some skylore is a bit more uplifting — tales of love, devotion, and sacrifice. One of those tales is told in the story of Castor and Pollux — the twins of Gemini — who are dropping down the western sky on these late spring nights. According to one version of the story, the queen of Sparta gave birth to two sets of twins — one boy and one girl in each pair. One set was fathered by her husband. But the other set was sired by Zeus, the king of the gods. The four children were raised together, and the two boys — one mortal, the other immortal — were inseparable. They had many adventures — they joined Jason and the other Argonauts in the search for the golden fleece, for example. But during a fight, the mortal Castor was killed. Pollux was inconsolable. He begged Zeus to allow him to die so he could join Castor. Moved by Pollux’s love for his brother, Zeus agreed to keep them together for all eternity. They spend their time in the heavens — where they’re represented by the stars of Gemini. The constellation is in the western sky at nightfall. Its brightest stars represent the twins themselves. They line up to the right of the Moon. Brighter Pollux is closer to the Moon, with Castor to its right.   Script by Damond Benningfield

  Ancient skylore is pretty tawdry. Everywhere you look, you find stories of betrayal, seduction, vanity, and even murder. Yet some skylore is a bit more uplifting — tales of love, devotion, and sacrifice. One of those tales is told in the story of Castor and Pollux — the twins of Gemini — who are dropping down the western sky on these late spring nights. According to one version of the story, the queen of Sparta gave birth to two sets of twins — one boy and one girl in each pair. One set was fathered by her husband. But the other set was sired by Zeus, the king of the gods. The four children were raised together, and the two boys — one mortal, the other immortal — were inseparable. They had many adventures — they joined Jason and the other Argonauts in the search for the golden fleece, for example. But during a fight, the mortal Castor was killed. Pollux was inconsolable. He begged Zeus to allow him to die so he could join Castor. Moved by Pollux’s love for his brother, Zeus agreed to keep them together for all eternity. They spend their time in the heavens — where they’re represented by the stars of Gemini. The constellation is in the western sky at nightfall. Its brightest stars represent the twins themselves. They line up to the right of the Moon. Brighter Pollux is closer to the Moon, with Castor to its right.   Script by Damond Benningfield

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  StarDate Podcast

  Ophiuchan Clusters

  Ophiuchus, the serpent bearer, climbs high across the southern night sky at this time of year. The constellation’s main pattern resembles a coffee urn. It’s on its side, low in the east, as night falls, but stands upright after midnight. Ophiuchus is north of Scorpius and Sagittarius, which point the way to the center of the Milky Way Galaxy. As a result, many star clusters are found inside its borders. The list includes 10 fairly bright globular clusters — tight balls of hundreds of thousands of stars. The one that’s most impressive to look at is Messier 10. It’s near the middle of the urn, and spans about half the size of the Moon. It’s a good target for binoculars, and a very good one for telescopes. The cluster looks so impressive mainly because it’s close — about 14,000 light-years away. It’s about 225,000 times the mass of the Sun. That’s a lot of stars. But it’s puny as globulars go. Most of the other clusters in Ophiuchus are much heavier. Messier 14, for example, is a million times the Sun’s mass. It doesn’t look as bright as M10, though, because it’s twice as far. And Messier 62 is even more impressive — about one-point-two million times the Sun’s mass. It’s closer than M14, but there’s more dust between M62 and Earth, which blocks some of its light. Even so, it’s visible through binoculars — one of the beautiful clusters of the serpent bearer.   Script by Damond Benningfield

  Ophiuchus, the serpent bearer, climbs high across the southern night sky at this time of year. The constellation’s main pattern resembles a coffee urn. It’s on its side, low in the east, as night falls, but stands upright after midnight. Ophiuchus is north of Scorpius and Sagittarius, which point the way to the center of the Milky Way Galaxy. As a result, many star clusters are found inside its borders. The list includes 10 fairly bright globular clusters — tight balls of hundreds of thousands of stars. The one that’s most impressive to look at is Messier 10. It’s near the middle of the urn, and spans about half the size of the Moon. It’s a good target for binoculars, and a very good one for telescopes. The cluster looks so impressive mainly because it’s close — about 14,000 light-years away. It’s about 225,000 times the mass of the Sun. That’s a lot of stars. But it’s puny as globulars go. Most of the other clusters in Ophiuchus are much heavier. Messier 14, for example, is a million times the Sun’s mass. It doesn’t look as bright as M10, though, because it’s twice as far. And Messier 62 is even more impressive — about one-point-two million times the Sun’s mass. It’s closer than M14, but there’s more dust between M62 and Earth, which blocks some of its light. Even so, it’s visible through binoculars — one of the beautiful clusters of the serpent bearer.   Script by Damond Benningfield