StarDate Podcast

The planet Venus is about to change addresses. It’s been shining as the brilliant “evening star” for several months now. But in just a few days it’ll leave the evening sky and move into the morning sky. It will reign as the “morning star” for most of next year. The planet is changing locations because it’s about to cross between Earth and the Sun. Venus is the second planet out from the Sun, while Earth is the third. Since Venus is closer to the Sun than Earth is, it moves faster in its orbit. So every 19-and-a-half months, Venus catches up to Earth and passes it by, crossing between us and the Sun. When that happens, Venus is temporarily lost in the Sun’s glare. But it doesn’t stay lost for long. Venus is closest to Earth as it passes us, at a distance of about 25 million miles. At that range, it scoots across the sky in a hurry, so it doesn’t stay out of sight for long. Right now, Venus is low in the west-southwest at sunset, and becomes visible through the glare of twilight a few minutes later. It outshines everything else in the night sky except the Moon, so as long as you have a clear horizon, you can’t miss it. The planet will drop lower in the sky over the next few evenings, though, becoming tougher to see in the solar glare. It’ll cross between Earth and Sun on January 11th, and then climb into easy view in the morning sky within a few days — beginning a reign as the “morning star” that will last until early autumn. Script by Damond Benningfield, Copyright 2013 For more skywatching tips, astronomy news, and much more, read StarDate magazine.

New Year’s Eve is almost upon us — a time when just about everybody is up and about at midnight. And coincidentally, it’s a good time of year to watch the midnight sky, which hosts some of the brightest stars and most beautiful constellations in the heavens. And you can view that same lineup tonight and throughout the week. To start your tour of the midnight sky, look high in the southeast for the planet Jupiter. It’s the brightest object in the sky at that hour, shining like a brilliant cream-colored star. The second-brightest object is in the south, to the lower right of Jupiter: the Dog Star, Sirius, which is the brightest true star in the night sky. Orion, the hunter, stands to the upper right of Sirius. Look for a short line of three bright stars that aims toward Sirius. That line is Orion’s Belt. The hunter’s two brightest stars stand about equal distances above and below the belt. A little farther to the northwest, you’ll come to Taurus, the bull. A V-shaped pattern of stars outlines its face, with orange Aldebaran as its baleful eye. The bright star high overhead is yellow-orange Capella. The “twins” of Gemini, Pollux and Castor, are back over in the southeast, near Jupiter. And W-shaped Cassiopeia, the queen, is dropping down the northwestern quadrant of the sky, while the Big Dipper is climbing across the northeast. So ring out the old year and ring in the new over the next few nights — with the help of the stars. Script by Damond Benningfield, Copyright 2013 For more skywatching tips, astronomy news, and much more, read StarDate magazine.

A nearby stellar neighbor climbs into good view at this time of year. Procyon is the leading light of Canis Minor, the little dog, so it’s known as the Little Dog Star. It’s only about 11 light-years away, so it shines brightly in our sky. It’s low in the east by about 8 o’clock, and climbs high across the south later on. Astronomers recently pieced together Procyon’s life story. It’s a binary — two stars that orbit each other once every 41 years. One of the stars is bright, while the other is faint. The bright star is a bit hotter and more massive than the Sun, so it shines pale yellow. Over the eons, a star’s size and brightness change. By matching the properties of Procyon’s brighter star to models of how stars age, astronomers deduced that it was born almost two billion years ago. That means the star is only 40 percent as old as the Sun. When our solar system was that age, Earth had primitive life. No one knows, however, whether Procyon has any planets, let alone whether such worlds are home to life. The fainter star was once much brighter than it is now. Astronomers estimate it was about 2.6 times as massive as the Sun when it was born. In its youth, it shined brilliant blue. In fact, it was brighter than its companion. But the star expelled its outer layers into space, leaving only its small, dead core — a cosmic cinder known as a white dwarf. Script by Ken Croswell, Copyright 2013 For more skywatching tips, astronomy news, and much more, read StarDate magazine.

Seismologists use earthquakes to study the structure of the planet beneath our feet. And now, astronomers may use something similar to probe the interior of the planet Saturn. Saturn is a very different world from Earth. It’s almost a hundred times heavier than our planet, and it consists of a dense, rocky core that’s surrounded by layers of hydrogen and helium. Saturn is best known for its bright, beautiful rings. Recently, planetary scientists detected structures in those rings that are created by vibrations within the planet. That allows the rings to act as a seismograph that probes Saturn’s interior. The scientists studied the innermost of Saturn’s bright rings, the C ring. Because it’s closest to the planet, it’s most susceptible to slight changes in Saturn’s gravitational field. Scientists looked at the ring with the Cassini spacecraft, which is orbiting Saturn. By looking at stars that passed behind the C ring, the scientists measured exactly how much light different parts of the ring absorb. With this technique, the researchers mapped six waves in the ring. The waves matched predictions for how the rings should respond as Saturn’s interior sloshes around and disturbs its gravitational field. Scientists will look for additional waves to help them understand the structure of this giant world. Look for Saturn before dawn tomorrow. It looks like a bright golden star close to the lower left of the crescent Moon. Script by Ken Croswell, Copyright 2013 For more skywatching tips, astronomy news, and much more, read StarDate magazine.

Forty years ago this week, Czech astronomer Lubos Kohoutek was talking to the people with the best view of a comet he’d discovered a few months earlier — the astronauts aboard the Skylab space station. KOHOUTEK: It is a great pleasure for me to greet you as the first human beings studying a comet from outer space. Comet Kohoutek had been touted as the comet of the century — a visitor that would outshine everything except the Moon at Christmas of 1973. Instead, the comet fizzled. It was barely visible, and few members of the general public ever saw it. Even now, astronomers keep Kohoutek in mind when they discuss the possible appearance of a new comet, such as ISON, which was scheduled to make its closest pass by Earth today. Despite the bad PR, Kohoutek was a scientific hit. Astronomers organized a worldwide campaign to study it with space- and ground-based instruments. By far the best view came from Skylab. The final flight to the space station had been timed so the crew could study the comet. The astronauts used telescopes designed to study the Sun to snap hundreds of pictures, and an instrument left over from the Apollo days to measure the comet’s ultraviolet light. And on December 30th, astronauts Edward Gibson and Gerald Carr observed it during a spacewalk. SKYLAB: Hey, I can see the comet! Lookit, right out there — see it? Holy cow, yes! Oh, yeah, beautiful! Very wide, broad tail. Unfortunately for everyone else, though, you had to be high above Earth’s atmosphere to enjoy the view. Script by Damond Benningfield, Copyright 2013 For more skywatching tips, astronomy news, and much more, read StarDate magazine.

Over the decades, Mars has been at the center of many controversies, some of which have concerned the question of life. The most famous is the idea that an ancient civilization built a network of canals across the Red Planet. And another controversy is still playing out: the possibility that microscopic organisms are emitting methane into the Martian atmosphere. In recent years, a couple of ground-based studies detected small amounts of methane in the atmosphere. So did the Mars Express spacecraft, which entered orbit around the planet 10 years ago this week. Most of the methane in our atmosphere is produced by living organisms. So the discovery on Mars suggested the possibility of life — perhaps in the form of microscopic organisms below the surface. But methane can also come from volcanoes and other processes, so life was far from a solid conclusion. It got less solid this year. Observations by the Curiosity rover on the Martian surface found no methane in the air around its landing site. Scientists are using other instruments on the rover to try to confirm the finding, while other groups re-examine the detection by earlier experiments — an effort to solve the controversy over methane in the Martian atmosphere. Mars is in great view early tomorrow. At first light, it’s close to the upper right of the Moon, and looks like a bright orange star. The true star Spica is about the same distance to the lower left of the Moon. Script by Damond Benningfield, Copyright 2013 For more skywatching tips, astronomy news, and much more, read StarDate magazine.

The Moon and the planet Mars will form a beautiful Christmas-morning decoration tomorrow. They’ll stand high in the south at first light, with orange Mars close to the upper left of the Moon. As a bonus, the bright star Spica will stand to their lower left. The scientists who study Mars got an early Christmas present 10 years ago today, when Europe’s Mars Express spacecraft entered orbit around the planet. It marked the first successful Mars arrival for any group other than the United States or the Soviet Union. Mars Express carried the best camera to arrive at Mars to that time. In the decade since, it’s snapped thousands of amazing views of the Red Planet, showing canyons, craters, flood channels, sand dunes, and other features in exquisite detail. The craft also was equipped with a laser altimeter, which has helped scientists measure the contours of the Martian landscape, as well as ground-penetrating radar. That instrument has helped reveal deposits of water ice beneath the surface. The arrival at Mars wasn’t a complete success, though. A small lander, known as Beagle 2, hitched a ride with Mars Express. It deployed from the orbiter on time, headed for the Martian surface. Engineers lost contact during its descent, though, and Beagle 2 was never heard from again. But Mars Express continues to probe the mysteries of the Red Planet, a decade after its arrival. We’ll have more about Mars, the Moon, and Spica tomorrow. Script by Damond Benningfield, Copyright 2013 For more skywatching tips, astronomy news, and much more, read StarDate magazine.

If Santa’s especially generous this year, you might find something shiny in your Christmas stocking: gold. As you admire it, think about this: that bit of soft, beautiful metal just might have been created during the birth of a black hole. Almost all of the chemical elements are created by stars, either during their long lifetimes, or in supernovae — the explosive deaths of heavy stars. But some recent research says that some of the heaviest elements may require multiple stellar deaths. Six months ago, an orbiting satellite detected a brief but powerful explosion known as a gamma-ray burst. It most likely was the result of the merger of two neutron stars — the corpses of once-mighty stars that had already exploded. The collision formed a black hole. But the violent outburst that accompanied the merger blasted away some material before it could fall into the black hole. Astronomers studied the afterglow of this hot cloud. The afterglow showed that the ejected material included some of the heaviest elements, which are difficult if not impossible to make in normal supernova outbursts. That includes a lot of gold — enough to make 10 Moons. These kinds of mergers are rare — there’s probably only one every hundred thousand years in our own galaxy. But the researchers say that over cosmic time, they could account for all of the gold in the universe — a bounty of beauty from the birth of black holes. Script by Damond Benningfield, Copyright 2013 For more skywatching tips, astronomy news, and much more, read StarDate magazine.

The surface of the Moon is a battered and barren landscape. Its main features are vast volcanic plains and rugged mountain ranges. But its most common features are impact craters — bowl-shaped structures that formed when space rocks slammed into the lunar surface at high speeds. Actually, not all of the craters were formed by rocks. A few dozen were formed by blobs of metal — spacecraft or rocket stages launched by the United States or Soviet Union. Some of the impacts were accidental, formed by probes that were out of control. Most were intentional, though, with some serving as parts of scientific experiments. Some of the booster rockets and lunar modules that carried Apollo astronauts to the Moon, for example, were rammed into the surface to create “moonquakes.” Instruments that the astronauts left on the surface measured the quakes, providing important information about the Moon’s structure and composition. And several craft have been aimed at the lunar poles. The impacts blasted up plumes of dust that scientists examined for particles of ice. The most recent of these impacts confirmed that ice does exist near the south pole. The craters gouged by these impacts are too small to see from Earth, although several have been photographed by a Moon-orbiting spacecraft. But you can see the Moon itself tonight. It rises in late evening, with the bright star Regulus, the heart of Leo, the lion, rising above it. Script by Damond Benningfield, Copyright 2013 For more skywatching tips, astronomy news, and much more, read StarDate magazine.

To many cultures, the winter solstice was a day when the life-giving Sun seemed to have deserted the world. These cultures held ceremonies to seek the Sun’s return. But they had to know just the right day for those ceremonies. So they appointed priests or chiefs to watch the Sun from special locations. In some cases, those spots were crafted so the Sun would cast light or shadows on representations of the Sun at sunrise or at noon. One of the most famous examples was at Chaco Canyon, in northwestern New Mexico. At noon on the winter solstice, two slashes of sunlight flanked a spiral that represented the Sun. Sunlight penetrated the center of the spiral on the summer solstice — the longest day of the year — but left it in shadow on the winter solstice. Another example is near Paint Rock, Texas. As the Sun stands highest in the sky, a dagger of sunlight stabs through the heart of a red painting that depicts a shield — a possible symbol for the Sun. The dagger crosses the shield only around the winter solstice. A University of Texas astronomer confirmed that the shield-and-dagger probably was an intentional alignment — part of an annual ritual designed to bring warmth back to the Texas hills. And that alignment takes place today. The winter solstice occurs at 11:11 a.m. Central Time, when the Sun stands farthest south for the year. It will soon begin to move northward — slowly restoring its life-giving rays to northern climes. Script by Damond Benningfield, Copyright 2013 For more skywatching tips, astronomy news, and much more, read StarDate magazine.

[AUDIO: EX HYA bossa music] Astronomy is a visual science. Astronomers can see their targets, or convert the data gathered by their instruments to graphs or other images. But some astronomers have found ways to convert some of that data to sound. That provides a different method for seeking out patterns, which can offer new insights into the workings of the universe. One project is called Star Songs. It began when Wanda Diaz Merced, a blind graduate student, was working toward her doctorate at the Harvard-Smithsonian Center for Astrophysics. She was using some NASA-developed software to create audio from X-ray observations of EX Hydrae, a strange binary star system. One star in the system “steals” gas from the other. That creates a disk of hot gas and high-powered jets of gas, and leads to some occasional outbursts. Gerhard Sonnert, a staff researcher who’s also a musician, saw rhythms in the printed versions of her work. He teamed up with a composer, who used the audio data as the basis for nine musical pieces, which were done in different styles. This section of data became a waltz, recorded by a trio that included Sonnert and the composer. [AUDIO: EX HYA waltz music] So “Star Songs” not only provides a new way to understand the stars, it provides a new way to appreciate their beauty as well. Script by Damond Benningfield, Copyright 2013 For more skywatching tips, astronomy news, and much more, read StarDate magazine.

Just because a star is small doesn’t mean it’s boring. In fact, two tiny stars in the constellation Hydra are among the most active in our region of the galaxy. One of the stars takes hot gas from the other, which triggers occasional outbursts. EX Hydrae is about 200 light-years away. Its main star is a white dwarf — the dead core of a once-normal star. It’s about a third as massive as the Sun, but only about as big as Earth. It’s so dense that its surface gravity is quite powerful — strong enough to pull material off the surface of its companion. That star is a red dwarf — a bare cosmic ember just one-tenth as massive as the Sun. The stolen gas falls on the white dwarf in a couple of ways. Most of it forms a wide, thin disk around the white dwarf. The disk gets extremely hot, so it produces lots of X-rays. But the white dwarf also generates a strong magnetic field. Some of the stolen gas follows the lines of magnetic force and flows onto the star’s poles. Every few years, so much gas piles up in the disk around the white dwarf that the disk can’t handle it. That triggers an outburst that makes the system flare about 10 times brighter than normal. It lasts only a few days before EX Hydrae returns to normal — a pair of small but busy stars. And a team of scientists and musicians has converted data from EX Hydrae into sound — and music. We’ll have more about that tomorrow. Script by Damond Benningfield, Copyright 2013 For more skywatching tips, astronomy news, and much more, read StarDate magazine.

Stars are giant nuclear reactors. Gravity squeezes them so tightly that their cores heat up to tens of millions of degrees. At such temperatures, atoms zip around so fast that they ram into each other and stick together. That “fusion” process creates heavier elements, while releasing an enormous amount of energy. A century ago, though, astronomers didn’t know about the fusion part of the process. Instead, one leading theory said the stars shined only because of the first part of the process — the gravitational contraction that heats their cores. That process does power the hearts of giant planets. The best example is Jupiter, the largest planet in the solar system. Gravitational contraction generates a tremendous amount of heat. That energy radiates through the planet’s layers of gas and out into space. In fact, Jupiter radiates more than twice as much energy into space as it receives from the Sun. But there’s not enough heat to make Jupiter shine in the visible part of the spectrum, as a star does. Instead, it shines in the infrared, which is visible to special detectors. Indeed, Jupiter is one of the brightest infrared objects in the sky. Jupiter does shine brightly at visible wavelengths, but it’s light reflected from the Sun, not generated by the planet itself. And you can see just how bright Jupiter is tonight. It looks like a brilliant star to the left or upper left of the Moon as they climb into good view this evening. Script by Damond Benningfield, Copyright 2013 For more skywatching tips, astronomy news, and much more, read StarDate magazine.

Black holes don’t have especially good table manners. They’re ravenous eaters, sometimes devouring entire stars at a single meal. And they sometimes leave a big mess around them, expelling clouds and jets of material into space. An example may be in the heart of NGC 660, a galaxy more than 40 million light-years away in the constellation Pisces. A team of astronomers was studying NGC 660 and several other galaxies with a giant radio telescope. Over a period of a few years, the core of NGC 660 grew much brighter. Follow-up observations with a network of radio telescopes showed that the outburst almost certainly came from the supermassive black hole at the galaxy’s center. The black hole may be “feeding” on a disk of hot gas that’s spiraling inward. Powerful magnetic fields shoot some of the gas back into space before it enters the black hole. That forms high-speed jets that can stretch across many light-years. The jets appear to be wobbling like streams of water from a spinning lawn sprinkler. The jets hit surrounding clouds of gas and dust, causing the clouds to glow brightly at radio wavelengths. If that’s the correct scenario, then the heart of NGC 660 is being lit up by part of a meal that’s escaping the jaws of a black hole. Pisces stretches across the south as night falls this evening. You need a telescope to see NGC 660, along the border between Pisces and the adjoining constellation Aries. Script by Damond Benningfield, Copyright 2013 For more skywatching tips, astronomy news, and much more, read StarDate magazine.

Romantics and werewolves take note: There’s a lot of moonlight the next few nights — more than at any other time of the year. The middle of the country, for example, will see about 14-and-a-half hours of moonlight the next three nights, after the day brings just nine-and-a-half hours of sunlight. That extra lunar glow is the result of the Moon’s phase and the time of year. The Moon will be full in the wee hours of tomorrow morning. It lines up opposite the Sun in the sky, so it rises around sunset and sets around sunrise. And we’re just a few days away from the winter solstice — the shortest day of the year in the northern hemisphere. The shortest days are accompanied by the longest nights. So December’s full Moon is known as the Long Night Moon. Not only does the Moon remain in view for a long time, it also climbs highest across the sky for the year. That’s because the Moon lies close to the ecliptic, which is the Sun’s path across the sky. At this time of year, the ecliptic arcs low across the sky during the day because Earth’s north pole is tipped away from the Sun. But the full Moon is on the opposite side of Earth, so the north pole tips toward it. As a result, the ecliptic climbs high across northern skies — and so does the full Moon. The exact moment of the full Moon, by the way, is 3:29 a.m. Central Standard Time — the time of the Long Night Moon. Tomorrow: The glow of escaping table scraps. Script by Damond Benningfield, Copyright 2013 For more skywatching tips, astronomy news, and much more, read StarDate magazine.