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  • The afternoon sky will get a little darker than normal for most of the United States tomorrow. That’s because there’s a partial solar eclipse. A solar eclipse occurs when the new Moon passes directly between Earth and the Sun. Most months, the Moon skims just above or below the Sun as seen from Earth, so there’s no eclipse at all. This eclipse is only partial — the Moon will cover only a portion of the Sun’s disk. So the sky will resemble an early dusk, and the temperature may drop a little bit. The eclipse begins when the Moon’s shadow first touches Earth, over Siberia, around 2:30 p.m. Central Time. The shadow then spreads to the southeast, crossing Alaska, Canada, then the Lower 48 states. The eclipse will be deeper from points farther north and west. From Anchorage, for example, the Moon will cover more than half of the Sun’s disk at the point of greatest eclipse. Only a third of the Sun will be eclipsed from Los Angeles and Dallas, though, and only a tiny notch will be missing as seen from New York and Miami. In fact, for those in the eastern third of the country, the eclipse will still be in progress at sunset. Keep in mind that it’s not safe to look at the eclipse directly — the Sun is still bright enough to damage your eyes. Instead, look through dark welder’s glass. You can also track the eclipse by looking at the ground under a leafy tree, where the gaps in the leaves create neat little pictures of this celestial lineup.   Script by Damond Benningfield, Copyright 2014 For more skywatching tips, astronomy news, and much more, read StarDate magazine.

  • The afternoon sky will get a little darker than normal for most of the United States Thursday. That’s because there’s a partial solar eclipse, according to the editors of StarDate magazine. read more

  • The stars move across the sky with clockwork precision. So perhaps it’s not surprising that a company that made timepieces took advantage of the stars — to improve both its watches and its image. The Elgin National Watch Company was established in Illinois in 1864 — 150 years ago — and it quickly became one of the world’s leading watchmakers. And in 1910, it built its own astronomical observatory to track the time. The observatory used a transit telescope, which measured the precise time that bright stars crossed the meridian — the line across the sky that passes from due north to due south. Comparing those times with astronomical almanacs revealed the precise time at the company’s factory. That time was kept by a set of high-precision German clocks, which were sealed inside a climate-controlled room. This method was accurate to within a tenth of a second. Time signals were transmitted to the factory to allow workers to precisely set new watches. Elgin built its entire image around the observatory. The company’s ads featured pictures of it, and encouraged readers to “Go to the Stars for the Time.” After World War II, though, atomic clocks began providing more accurate time, and less-expensive brands pushed Elgin watches aside. The company donated the observatory to the local schools in 1960, and it still stands today. The company, alas, does not. It shut its doors and sold off its name in 1968.   Script by Damond Benningfield, Copyright 2014 For more skywatching tips, astronomy news, and much more, read StarDate magazine.

  • Upsilon Andromedae might not dazzle the eye, but one fact really makes it sparkle: It’s one of the brightest stars in the night sky known to have four or more planets. The star is bigger, brighter, and heavier than the Sun. It has a distant companion star that’s a faint cosmic ember. The two stars are known as Upsilon Andromedae A and B. The planets orbit star A, so they’re known as Upsilon Andromedae A-b, A-c, A-d, and A-e. That’s a neat system for the astronomers who study planets in other star systems — it helps them know just where everything is. For the rest of us, though, the system’s a bit dull. Such names have none of the appeal of Vulcan, Gallifrey, Arrakis, or many other planet names from science fiction. But that’s about to change. The International Astronomical Union is holding a contest to name more than 300 exoplanets, including those of Upsilon Andromedae. Over the next few months, it’ll accept proposals for exoplanet names from astronomy-related groups, such as planetariums and museums. It’ll pick the best proposals next spring, and allow the general public to vote on the names. It’ll formally adopt the new names next summer — adding a little character to some distant worlds. Upsilon Andromedae is about a third of the way up the east-northeast sky at nightfall, and stands directly overhead in the wee hours of the morning. Although it’s visible to the unaided eye, you’ll need a starchart to pick it out.   Script by Damond Benningfield, Copyright 2014 For more skywatching tips, astronomy news, and much more, read StarDate magazine.

  • A thin but reliable meteor shower is at its best the next couple of nights. The view is best in the wee hours of the morning, when you might see a dozen or two “shooting stars” per hour. The Orionids occur when Earth sweeps through the orbital path of Comet Halley, which has been making periodic trips through the inner solar system for more than two millennia. It sheds bits of dusty debris on each trip, which spread out along the comet’s path. These particles zip into Earth’s upper atmosphere at speeds of up to 140,000 miles an hour. They quickly vaporize, forming the glowing streaks known as meteors. Although the shower probably has been around for centuries, no one took formal note of it until 175 years ago. Edward Herrick of Yale College recorded a clump of meteors in October of 1839. He confirmed the activity the following year. Herrick didn’t find the shower’s peak, though — the period of a few hours with the greatest number of meteors. That was left to Alexander Herschel, who made the discovery 150 years ago, in 1864. The intensity of the Orionids waxes and wanes over the years. That’s because the meteor stream is clumpy. If we happen to pass through a denser clump of comet dust, we see more meteors. This isn’t expected to be one of those years. Even so, there’s not much moonlight to interfere with the fireworks. So if you have dark, clear skies in the hours before dawn the next few mornings, keep an eye out for the Orionid meteor shower.   Script by Damond Benningfield, Copyright 2014   For more skywatching tips, astronomy news, and much more, read StarDate magazine.

  • Mars is low in the southwest as night falls. It looks like a fairly bright orange star. And if you have strong binoculars or a telescope, you might make out a fuzzy companion quite close to the planet the next few evenings. Comet Siding Spring will be just to the left of Mars tonight, and closer to the right of Mars tomorrow night. The comet could create a brief but intense meteor shower on Mars tomorrow, as a barrage of dust grains slams into the planet’s upper atmosphere. Debris from a different comet will strafe Earth over the next few nights, spawning our own meteor shower. It’s not a great one, but there’s not much moonlight around to interfere with the fireworks, so it’s worth a look. The Orionid shower is created by Comet Halley. The comet hasn’t visited the inner solar system in a quarter of a century. But as it orbits the Sun, it sheds small bits of rocky debris. These grains of dust spread out along Halley’s orbital path. Earth flies through this path every October, so some of the grains slam into the atmosphere at tens of thousands of miles per hour. They quickly vaporize, forming the glowing streaks of light known as meteors or shooting stars. The Orionids should be at their best tomorrow and Monday nights, although you might see a few outliers tonight as well. The shower is best viewed in the wee hours of the morning, as your part of Earth turns most directly into the meteor stream — a strafing run from a distant comet.   Script by Damond Benningfield, Copyright 2014 For more skywatching tips, astronomy news, and much more, read StarDate magazine.

  • Mars is about to dodge a big snowball — a comet that will swing just 82,000 miles above the planet’s surface on Sunday, according to the editors of StarDate magazine. That’s just a third of the distance between Earth and the Moon, so it’s quite a close call. Comet Siding Spring will not be visible from Earth with the unaided eye, but it will be a spectacular sight under the dark Martian sky. It could even spawn a short but brilliant meteor shower caused by the dust grains plunging into the Martian atmosphere. read more

  • The fleet of Mars-orbiting spacecraft will hide behind the Red Planet on Sunday morning. They’ll be trying to avoid a possible bombardment by tiny cosmic missiles — grains of dust from a comet. Although many of those grains are no bigger than a BB, they’ll be moving at about 125,000 miles an hour — fast enough to damage or even destroy a spacecraft. Comet Siding Spring will pass about 82,000 miles from Mars early Sunday — only a third of the distance from Earth to the Moon. That should create quite a show in the Martian sky — not just the view of the comet itself, but a possible meteor shower caused by the dust grains plunging into the Martian atmosphere. The atmosphere will protect rovers on the surface of Mars. But orbiters are vulnerable to the dust grains. So navigators have tweaked their orbits to keep the craft on the other side of Mars at the time of the greatest threat. Before and after that, however, the orbiters will keep a close eye on the show. They’ll study the comet itself, which is a small chunk of ice and rock. They’ll also study the cloud of gas and dust around the comet, as well as its long tail. And they’ll measure how the gas and dust interact with the Martian atmosphere — after Siding Spring has passed safely by. We’ll talk about a meteor shower here on Earth tomorrow.   Script by Damond Benningfield, Copyright 2014 For more skywatching tips, astronomy news, and much more, read StarDate magazine.

  • Comet Siding Spring will pass about 85,000 miles above Mars on October 19, as depicted in this artist's concept. Several Mars orbiting spacecraft will "hide" behind Mars to protect themselves from possible cometary debris. The orbiters, as well as two rovers on the surface, will study the comet before and after its close encounter with Mars. [NASA/JPL] Text ©2014 The University of Texas at Austin McDonald ObservatoryFor more skywatching tips, astronomy news, and much more, read StarDate magazine.

  • Mars is about to dodge a big snowball — a comet that will swing just 82,000 miles above the planet’s surface on Sunday. That’s just a third of the distance between Earth and the Moon, so it’s quite a close call. The comet would be a spectacular sight under the dark Martian sky. And it could even spawn a short but brilliant meteor shower. Comet Siding Spring is making its first trip through the inner solar system. It’s spent almost its entire life in the Oort Cloud — a vast shell of icy bodies far from the Sun. Perhaps nudged out of its orbit by the gravity of a passing star, it’s been streaking toward the Sun for the last million years or so. Such comets are like icy time capsules — they preserve a record of the early solar system. Siding Spring probably formed fairly close to the Sun, from the same disk of debris that gave birth to Earth and the other planets. The gravity of one of the giant outer planets hurled it into the Oort Cloud. In the deep freeze of interstellar space, the comet has changed little since its formation. So as it zips toward the Sun, it gives scientists a chance to see a relic from the distant past — a snowball that preserves the same ingredients that gave birth to our own world. Spacecraft in orbit around Mars will watch the comet — but not all the time. Tiny bits of dust around the comet could be hazardous, so the craft will hide behind Mars for a while. We’ll have more about that tomorrow.   Script by Damond Benningfield, Copyright 2014 For more skywatching tips, astronomy news, and much more, read StarDate magazine.

  • Powerful radiation belts surround Jupiter, the solar system's largest planet. The strongest radiation zones are shown in yellow and red, which were mapped by the Cassini spacecraft. The radiation is powerful enough to kill a person in minutes. [NASA/JPL] Text ©2014 The University of Texas at Austin McDonald ObservatoryFor more skywatching tips, astronomy news, and much more, read StarDate magazine.

  • Approach the planet Jupiter at your own peril. Like something out of science fiction, it’s protected by its own magnetic shield — radiation belts that are strong enough to kill a person in just minutes. The belts are powered by Jupiter’s intense magnetic field, which traps electrically charged particles from the Sun. It also traps particles from the moon Io, where giant volcanoes belch material into space. Some of this material is given its own electric charge by encounters with the particles that are already in the belt. This produces an especially intense ring of radiation along Io’s orbit. Several spacecraft have flown past Jupiter, and one spent several years orbiting the planet. Their computers and other electronic systems had to be shielded against the radiation belts. The orbiter was kept away from the Io zone for most of its mission, yet by the end it was feeling the effects of prolonged exposure to the radiation. If people ever venture that far into the solar system, they’ll need even heavier shielding to protect them from Jupiter’s deadly radiation. Jupiter is climbing higher into the morning sky each day. The solar system’s largest planet looks like a brilliant star, high in the east-southeast at first light. The Moon takes aim at it for the next few days. Jupiter will stand well to the lower left of the Moon tomorrow, but will be much closer to the Moon on Friday and Saturday. Tomorrow: getting close to Mars.   Script by Damond Benningfield, Copyright 2014 For more skywatching tips, astronomy news, and much more, read StarDate magazine.

  • The Rosetta spacecraft snapped this image of one of its solar panels with Comet 67P/Churyumov–Gerasimenko in the background on October 7, at a distance of about 10 miles (16 km). A "jet" of gas is streaming into space from the surface of the comet, which consists of two lobes connected by a narrow neck. Rosetta will deploy a small lander on November 12. [ESA/Rosetta/Philae/CIVA] Text ©2014 The University of Texas at Austin McDonald ObservatoryFor more skywatching tips, astronomy news, and much more, read StarDate magazine.

  • The star at the heart of the swan is a case of “what you see is what you get.” Unlike most of the stars in its weight class, it puts out most of its energy at visible wavelengths. So we see the star in all its glory — across 1800 light-years of space. Sadr represents the breast of Cygnus, the swan, and the center of the Northern Cross, which is outlined by the swan’s brightest stars. It’s a supergiant — the biggest and heaviest class of all stars. Sadr itself is about 12 times as massive as the Sun, and close to 200 times the Sun’s diameter. If it took the Sun’s place in our own solar system, its surface would extend almost all the way out to Earth. Most supergiants shine either blue-white or reddish orange — an indication that their surfaces are much hotter or cooler than the Sun. Most of the radiation from these stars is at wavelengths that are invisible to the human eye — ultraviolet for hot stars, and infrared for cool stars. So while these stars look bright, the eye alone sees only a fraction of their total brightness. But Sadr is yellow-white, which means it’s not that much hotter than the Sun. Such stars emit most of their light at visible wavelengths. So when you look at Sadr, you’re getting the full force of its brilliance. For skywatchers in most of the United States, Sadr passes directly or almost directly overhead about an hour-and-a-half after sunset. It’s not far from another supergiant: Deneb, the swan’s brightest star.   Script by Damond Benningfield, Copyright 2014 For more skywatching tips, astronomy news, and much more, read StarDate magazine.

  • A Venus-orbiting spacecraft is playing out its final weeks. It could end its mission with a fiery plunge into Venus’s dense atmosphere by the end of the year. Venus Express entered orbit around the planet more than eight years ago. Its observations have showed that there’s water in the atmosphere, and that winds at the top of the atmosphere have been getting stronger. It also confirmed that lightning crackles through Venus’s clouds, and found hints of active volcanoes on the planet’s surface. But the European craft is almost out of fuel. So in late spring, flight controllers lowered its orbit to measure the density and temperatures of the upper atmosphere. At times, Venus Express dipped to within 80 miles of the surface. It survived the close encounter, and was brought back to a higher orbit. Even so, its time is just about up. Within a few months, it’ll drop back into the atmosphere. This time, it’ll burn up as it plunges toward Venus’s hot surface. That’s just what happened to another Venus orbiter 20 years ago today. Magellan had used radar to map the Venusian surface, which is hidden beneath an unbroken blanket of clouds. As it ran out of fuel, it was dropped to lower and lower altitudes to study the planet’s atmosphere. Engineers also studied how Magellan responded to the pressure and drag exerted by the atmosphere. That helped later missions use the Martian atmosphere to settle into orbit around the Red Planet.   Script by Damond Benningfield, Copyright 2014 For more skywatching tips, astronomy news, and much more, read StarDate magazine.

  • Dark lanes of gas hide many newborn stars inside the Elephant Trunk Nebula, which is part of a vast stellar nursery about 2,500 light-years from Earth. Radiation from a nearby hot, young star is blasting one side of the nebula, eroding its dust and gas. That also squeezes clumps of gas, causing them to collapse and give birth to new stars. [T.A. Rector (Univ. Alaska Anchorage)/WIYN/NOAO/AURA/NSF] Text ©2014 The University of Texas at Austin McDonald ObservatoryFor more skywatching tips, astronomy news, and much more, read StarDate magazine.

  • There’s something about clouds that inspires the imagination. Let a few puffs drift by on an autumn afternoon, and you might see a dragon or a droid or a long-lost friend. And the same thing happens when you look through a telescope. Many interstellar clouds have names that describe their resemblance to animals or objects here on Earth, from an eagle to the North American continent. Another one of those clouds stands high overhead this evening — the Elephant’s Trunk Nebula. It’s a dark, narrow ribbon with a bright rim. It’s silhouetted against a much larger cloud that’s about 2,500 light-years away. A hot, young star not far from the nebula is sculpting the elephant’s trunk. The star’s radiation acts like a blowtorch, eroding gas and dust on one side of the nebula. But it also squeezes some of the material together to make dense clumps, which may then collapse to form new stars. In fact, that region has given birth to many stars in the last couple of million years. Some of the stars are inside a dense knot at the tip of the elephant’s trunk. Strong winds from these stars push the gas and dust around them. Combined with the effects of the outside star, that squeezes the material between them even more — setting up the birth of more stars. The nebula is in the constellation Cepheus, which is high in the north on October evenings. You need a telescope to see it — an elephant’s trunk trumpeting the birth of new stars.   Script by Damond Benningfield, Copyright 2014 For more skywatching tips, astronomy news, and much more, read StarDate magazine.

  • A casual skywatcher who didn’t know much about the scale of the universe might get a little nervous watching the sky tonight. In fact, they might think we were headed for a cosmic catastrophe, because the Moon barrels toward the eye of the bull. Fortunately for us, though, we know there’s nothing to worry about. It’s all part of the clockwork motions of the heavens — something to enjoy, not fear. Aldebaran, the star that marks the bull’s eye, is close to the lower left of the Moon as they climb into good view by about 11 o’clock. As the hours roll by, though, the Moon moves closer and closer to the bright orange star. By the wee hours of the morning, they’ll be separated by less than a degree — not much more than the width of the Moon itself. Many ancient cultures feared such close encounters — they saw them as evil doings in the sky. Instead, they’re simply a matter of celestial geography. The Moon passes by Aldebaran every month. Many months, its path keeps it several degrees from the star. But occasionally, the Moon can not only pass close to Aldebaran, it can actually pass in front of it, covering the star from view. As the two bodies move closer, it can look like a collision is imminent. It’s not, though. The Moon is only a quarter of a million miles away — our closest astronomical neighbor. But Aldebaran is 67 light-years away — about 1.6 billion times farther than our friendly neighborhood Moon.   Script by Damond Benningfield, Copyright 2014 For more skywatching tips, astronomy news, and much more, read StarDate magazine.

  • Black holes are among the most popular objects in the universe. But they’re also among the most misunderstood. Among many misconceptions, they’re not as voracious as they’re often portrayed. A black hole is an object with such powerful gravity that nothing can escape from it, including light. Some were born from the collapse of supergiant stars, and are several times as massive as the Sun. Millions of these objects may speckle the Milky Way galaxy. When a star becomes a black hole, though, it doesn’t automatically suck up all the planets and other objects around it. If the Sun were to become a black hole, for example — something that’s not possible, by the way — Earth and the other planets wouldn’t “feel” anything different. Even though the black-hole Sun would be just a few miles in diameter, Earth would continue to orbit at the same speed and distance as it does today. So would Mars and Jupiter and Halley’s Comet. The point is that while the Sun’s size and energy output would change dramatically, its mass would remain the same, and it’s mass that determines an object’s gravitational pull, not its size. Objects that got too close to the black hole would be torn apart, and their remains would form a hot disk. As this material spiraled into the black hole, it would get extremely hot, so it would glow brightly. Beyond that close range, though, the rest of the solar system would go on as before — undisturbed by the nearby black hole.   Script by Damond Benningfield, Copyright 2014 For more skywatching tips, astronomy news, and much more, read StarDate magazine.

  • If you jump off a cliff, the moment you push off the ground is the point of no return; unless you’re a cartoon character, there’s no going back. Astronomy offers its own point of no return: the event horizon of a black hole. Pass through it and you’ll never see the outside universe again. A black hole is an object in which gravity overwhelms all the other forces of nature. The object’s entire mass — which can range up to billions of times the mass of the Sun — is squished into a pinpoint called a singularity. Anything that comes close enough to the singularity is trapped forever by its gravitational grip. The point of no return is the event horizon — the distance from the singularity where the escape velocity equals the speed of light. In essence, that makes it the surface of the black hole — the boundary between what’s inside the black hole and what’s outside. Even getting close to an event horizon would produce some interesting effects. For one thing, time would begin to pass more slowly as viewed by an outside observer. So as you approached the event horizon, someone watching from a safe distance would see you appear to slow down. You might not actually survive such a close encounter, though. If you approached the event horizon of a black hole a few times the mass of the Sun, there would be an extreme difference in the gravitational pull across a short distance. That would rip you apart — even before you reached the point of no return.   Script by Damond Benningfield, Copyright 2014 For more skywatching tips, astronomy news, and much more, read StarDate magazine.

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