StarDate

Billy Henry
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StarDate, the longest-running national radio science feature in the U.S., tells listeners what to look for in the night sky.

集數

  1. 1 天前

    Cosmic Artifacts

    The religion of ancient Egypt said that when a king died, his soul ascended to the heavens to join with the god Osiris, in the modern-day constellation Orion. His tomb was filled with items he might need to help him on his way. And in the case of at least one pharaoh, some of those items probably came from the heavens. The tomb of King Tutankhamen contained thousands of artifacts. Many of them were made of gold, including a dagger buried inside his coffin. But the boy king also had a second dagger, made of iron. When Tut was buried, more than 3300 years ago, Egypt hadn’t started to work with iron ore, so the dagger probably was made from an iron meteorite – a space rock that fell to Earth. The composition of the dagger’s metal is much like that of a metallic meteorite – a mixture of iron and nickel, with a pinch of cobalt. Another Tut artifact was an elaborate piece of jewelry known as a pectoral. Its centerpiece is a scarab beetle carved from yellow glass. The glass formed about 26 million years ago, when an asteroid or comet plunged toward Earth. It either hit the surface or exploded in the atmosphere. Heat from the explosion melted some of the desert sand, creating chunks of glass. One of those chunks eventually made its way to an Egyptian artist, and then to Tut’s tomb – a piece of glass from the heavens for a king traveling to the heavens. Tomorrow: into the void. Script by Damond Benningfield

  2. 2 天前

    Confusing Planet

    Planetary scientists have had a hard time classifying a world that orbits a faint star in Ophiuchus. Since the planet’s discovery in 2009, they’ve described it as a super-Earth, a mini-Neptune, and a super-Venus. In other words, it’s not like anything in our own solar system. The planet orbits the star GJ 1214. It’s in the serpent bearer, which is high above the Moon this evening. The star is less than 50 light-years away. But it’s less than one percent as bright as the Sun, so you need a good-sized telescope to see it. A few years ago, the International Astronomical Union assigned formal names to both the planet and the star. The names come from Kenya, from the Maa language. The star is Orkaria, from the name of a red pigment used by warriors in tribal ceremonies – the color of the star. The planet is Enaiposha – a word for lake or sea, or for their stormy nature. The planet is bigger and heavier than Earth. That led to its early classification as a super-Earth. But it’s not very dense, which makes it more like a miniature version of Neptune – the smallest of the Sun’s giant planets. Enaiposha has a thick atmosphere, which is hot because the planet is quite close to the star. Observations by Webb Space Telescope suggest the atmosphere contains a lot of carbon dioxide. That hot C-O-2 atmosphere makes the planet like Venus – one of several identities for this hard-to-classify world. Script by Damond Benningfield

  3. 3 天前

    Powerful Jets

    Cygnus X-1 contains the first black hole ever confirmed. And it recently recorded another first. Astronomers measured the details of twin “jets” of particles that shoot into space from its poles. The jets are firing at almost half the speed of light. And they have the power of 10,000 Suns. The system consists of the black hole and a supergiant star. The black hole, which was discovered in 1964, is 20 times the mass of the Sun. The star is twice that mass. The star is extremely hot and bright. It blows a thick wind of hot gas into space. The black hole captures some of the gas, which forms a swirling, super-hot disk around it. Magnetic fields grab some of the gas before it falls into the black hole, and fire it back into space through the jets. Astronomers have seen jets from many black holes. But this is the first time they’ve precisely measured a jet’s power and speed. Those details are important because the jets can have a big influence on the surroundings. They can blow away gas and dust, preventing the birth of more stars. Or they can squeeze clouds of gas and dust, triggering the birth of stars. So the details help us understand the role of black holes in the evolution of entire galaxies. Cygnus is in the eastern sky at nightfall. Although Cygnus X-1 is too faint to see, it’s about half way between the swan’s bill and the intersection of its body and wings. Script by Damond Benningfield

  4. 4 天前

    Moon and Antares

    Stars follow a life-long weight-loss program. They blow hot gas off their surfaces. Over time, the amount of material in these “winds” can add up. Heavier stars, in fact, can expel enough gas to make several stars as massive as the Sun. An example is Antares, the leading light of Scorpius. It’s in good view tonight, to the left of the Moon as night falls. Antares is a supergiant – one of the biggest and brightest stars in the galaxy. It’s more than a dozen times the Sun’s mass. And it’s so big that if you placed it at the center of the solar system, it would extend past the orbit of Mars. But when Antares was born, about 11 million years ago, it was even heavier. Studies in recent years have placed its initial mass at about 15 to 17 times the Sun’s mass. Most of the difference has been blown into space on the star’s winds. Antares has lost so much of its original weight because it was heavy to begin with. A massive star “burns” through its nuclear fuel quickly, making its core extremely hot. Radiation from the core causes the star’s outer layers to puff outward. That far from the core, the surface gravity is fairly low, so it’s easy for radiation to push gas out into space. Antares is fated to expel even more of its mass. At the end of its life, its core will collapse, causing its outer layers to explode as a supernova – blasting most of its remaining gas out into the galaxy. Script by Damond Benningfield

  5. 5 天前

    Red-Planet Skies

    A new era in the exploration of Mars opened 50 years ago this week, when the first of two Viking landers touched down there. The probes measured the weather and the composition of the Martian rocks and dirt. They looked for evidence of life. And they gazed into the sky, showing a reddish tint for most of the day, but blue at sunrise and sunset. That color is caused by dust in the atmosphere. The tiny dust grains are reddish brown. They scatter some of the sunlight – mostly red light, which makes the sky glow in shades of red. Depending on the time of day, the amount of dust, and other factors, the sky can range from butterscotch to apricot to bright pink. But as the Sun rises and sets, its light passes through a much thicker layer of the atmosphere. That filters out most of the red light, making the Sun and the sky look blue. There’s a lot of dust in the sky, and much of it floats quite high above the surface. So sunlight reflecting from the high-altitude dust extends the twilight, making the sky bright even when the Sun is well out of view. Mars is inching higher into our morning sky. It looks like a fairly bright orange star. It’s in the east at dawn. The star Elnath – the tip of one of the horns of Taurus – stands to the left of Mars. The bull’s eye, Aldebaran, is to the right of Mars. It’s a little brighter than Mars, but about the same color – the color of the Red Planet. Script by Damond Benningfield

  6. 6 天前

    Dead or Alive?

    One of the main goals of the twin Viking landers, which touched down on Mars 50 years ago, was to search for life. They found it. But then they didn’t. But maybe they really did. If that sounds confusing – well, it is. Scientists have been debating the findings since the beginning – and the debate is still going on. Viking 1 landed on July 20th, 1976, in a smooth plain north of the equator. It was the first fully successful landing. Viking 2 touched down six weeks later and 4,000 miles away. Both landers conducted several experiments to look for life. They scooped up some of the powdery dust and dumped it into chemical laboratories for analysis. In one experiment, they added water, nutrients, and a radioactive form of carbon. Any microbes in the samples should gobble up the nutrients and “exhale” the carbon. And that’s what appeared to happen – a sign of life. But other experiments came up empty. They looked for organic compounds – the building blocks of life. And they found nothing. According to most scientists at the time, that ruled out the possibility of life. Instead, the positive results were interpreted as complex chemical reactions. But many scientists continue to say the landers did find life. And over the past decade, there’s been a lively conversation about the results. So life at the Viking landing sites remains an open question. Script by Damond Benningfield

  7. 7月20日

    Viking 1

    In a field of volcanic rocks and red dunes on the planet Mars, an emissary from Earth sits quietly. Powdery dust may coat its white surface, possibly hiding the American flag and Bicentennial logo from view. Extreme cold might have cracked some of its lenses and other components. But if humans ever colonize Mars, they’ll certainly visit this relic – the first craft to successfully land on the Red Planet. The Viking 1 lander touched down 50 years ago today. It was one of four craft in the Viking project – two landers and two orbiters. Viking 1 wasn’t the first probe to touch down on Mars. The Soviet Union’s Mars 3 had landed in 1971. But it died less than two minutes later, so it didn’t return any information about Mars. The Viking 1 and 2 landers snapped thousands of pictures. They monitored the weather and measured the composition of the soil and atmosphere. The landers also looked for signs of life. Their cameras saw no moving objects on the surface, and no growing plants. Chemical laboratories found no organic molecules in the soil. They did find chemical reactions like those produced by microorganisms on Earth. But scientists at the time decided the reactions were produced by the soil, not life; more about that tomorrow. The Viking 1 lander operated for three Mars years – more than six Earth years. Scientists continue to study its findings to learn more about the intriguing Red Planet. Script by Damond Benningfield

  8. 7月19日

    Brilliant Nova

    A half a century ago, the swan’s tail feathers got a little singed. A bright “new” star – a nova – flared into view close to Deneb, the star that represents the tail. Known today as V1500 Cygni, it was one of the brightest novas ever seen. In a matter of hours, it grew about 40 million times brighter. It was visible to the unaided eye for several nights. And it took months to fade to its previous brightness. V1500 is actually two stars. One of them is a heavy white dwarf – a hot, dense “corpse.” The other is a red dwarf – a small, cool, faint star that’s still in the prime of life. The white dwarf is pulling gas from its feeble companion. Powerful magnetic fields funnel it onto the white dwarf. As the gas piles up on the white dwarf, the dead star’s gravity squeezes it into a thin layer, making the gas hotter and hotter. In 1975, that layer got so hot that it exploded in a massive nuclear inferno. The blast disrupted the flow of material, and heated the surface of its companion – which is still cooling off. Today, the white dwarf is stealing more gas from the companion. So it may flare up again in the centuries ahead – making things a bit uncomfortable for the tail of the swan. Cygnus is high in the east at nightfall, anchored by Deneb. V1500 is close to the lower left of Deneb, but much too faint to see without a telescope – for now. Script by Damond Benningfield

  9. 7月18日

    Nova Watch

    Corona Borealis, the northern crown, could be about to add another jewel – at least for a while. A star system there has been flaring up every 80 years. The last outburst was in 1946, so it’s due for the next one. T Corona Borealis is actually a binary – two stars locked in a mutual orbit. One of them is a white dwarf – the “corpse” of a star that was once like the Sun. The other is a red giant – a star that’s puffed up as it nears the end of its own life. The white dwarf pulls hydrogen off the surface of its bloated companion. The gas forms a spinning disk around the white dwarf. Gas at the inner edge of the disk spirals onto the white dwarf. The white dwarf’s gravity is quite strong, so the infalling gas is squeezed into a thin layer and heated to tens of millions of degrees. That eventually triggers a runaway nuclear explosion – like a giant hydrogen bomb. The outburst is known as a nova – a Latin word that means “new.” When the “bomb” goes off, the system shines tens of thousands of times brighter than average. That makes it visible to the eye alone, even though it’s 3,000 light-years away. So keep an eye out for this “new” jewel in the northern crown. Corona Borealis is high in the southwest at nightfall. It’s an upside-down semicircle of stars, with the brightest star at its middle. T Corona is close to the top left end of the semicircle. We’ll talk about another bright nova tomorrow. Script by Damond Benningfield

  10. 7月17日

    Moon and Venus

    There are no traffic signals in lunar orbit. And for the most part, they’re not needed – at least not yet. Only about a dozen spacecraft are circling the Moon. But every once in a while, they can pass dangerously close to each other. And that triggers a “red alert” – a warning to the operators of both craft. It might sound surprising that there’s ever any kind of problem – there’s a lot of space around the Moon. But many of the spacecraft follow similar orbits. Many of them orbit from pole to pole, allowing them to study the entire lunar surface. And there’s no system for tracking the second-by-second locations of the orbiters. Instead, NASA engineers with a project called MADCAP track the “orbital elements” of every craft in orbit around the Moon and Mars – a set of details that includes altitude, the angle of the orbit, and much more. Computers constantly plot the motions of every craft for which they have those details. If it looks like there might be a dangerously close encounter, the alert goes out. Operators of the conflicting missions then get together to find a solution. Overall, the number of alerts is small. But in December 2024 it jumped to more than 20. And with more lunar missions scheduled, we can expect more “red alerts” in the years ahead. The crescent Moon is in the west as darkness falls. The brilliant planet Venus – the “evening star” – is close to the right. Script by Damond Benningfield

  • 共 10 集

主持人與來賓

簡介

StarDate, the longest-running national radio science feature in the U.S., tells listeners what to look for in the night sky.

資訊

  • 創作者
    Billy Henry
  • 活躍年代
    2017年 - 2026年
  • 集數
    10
  • 年齡分級
    兒少適宜
  • 版權
    © 2022 The University of Texas McDonald Observatory
  • 節目網站
    StarDate

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