Most scientists agree that a large asteroid strike 65 million years ago ended the dinosaurs’ reign on Earth. Some think that a single strike did the trick, while others think it was multiple strikes and additional stresses that pushed the dinosaurs into extinction. New evidence from researchers at the University of Missouri-Columbia supports the single impact hypothesis. They found a single layer of impact-related material in the geologic record that exactly matched marine creatures known to be contemporaries of the dinosaurs. They didn’t find any other impact evidence above or below this layer, reducing the possibility of additional impacts.
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Podcast: Where Do Baby Stars Come From?
Most parents have had that uncomfortable conversation with their children at some point. Mommy, Daddy, where do stars come from? You hem and haw, mumble a few words about angular momentum and primordial hydrogen and then cleverly change the subject. Well, you don’t have to avoid the subject any longer. Pamela and Fraser describe formation of stars, large and small, in a tasteful manner, using only understandable and scientific language.
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Set Your Clock with Gamma Rays
Astronomers have discovered a gamma ray source in the sky that acts like a natural clock. The object is called LS 5039, and consists of a massive blue star orbiting an unknown object – possibly a black hole. The two objects orbit each other closely, completing an orbit every four days. With each orbit, the black hole flies through the blue star’s stellar wind, and accelerates particles to gamma ray levels. This is the first time a source of gamma rays has been discovered with such a regular schedule.
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Daphnis Walks the Knife Edge
Saturn’s tiny moon Daphnis makes waves as it orbits the Ringed Planet. Even though it’s only 7 km (4.3 miles) across, the moon’s gravity draws material along the edges of the Keeler gap, creating the serrated knife edge you see in this picture. Cassini took this photo on Ocrober 27, 2006 when it was approximately 325,000 kilometers (202,000 miles) from Daphnis.
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New Horizon’s First View of Pluto
Take a look at this photograph. See Pluto? It’s that little orange speck. This photograph was taken by the Pluto-bound New Horizons spacecraft. Although Pluto is just a tiny dot today, it’s going to get a lot bigger over the next 10 years when the spacecraft makes its close encounter in 2015. New Horizons used its Long Range Reconnaissance Imager (LORRI) to capture images of Pluto’s region of space over several days. Scientists then analyzed the images, looking for an object moving at the right speed across several frames.
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Black Hole Erupts on Camera
ESA’s Integral space observatory has spotted a blast of gamma rays from a suspected black hole in the Milky Way. the outburst occurred on September 17, 2006, and gradually built in brightness over the course of a few days before declining again. It’s this rise and fall of brightness, called a light curve, that allowed astronomers identify the source as a black hole. It’s likely that a disk of gas and material orbiting the black hole became unstable, and a portion of it collapsed, creating the outburst.
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What’s Up this Week: November 27 – December 3, 2006
Greetings, fellow SkyWatchers! Sister Selene is back en force, so why not take a few evenings to catch up on some lunar features? If you want to double your pleasure and double your fun – why not look at binary stars instead of just one! Time to dust off the telescope and head out into the night, because…
Here’s what’s up!
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The Last of the Great Observatories
The Spitzer telescope targets the infrared portion of the light spectrum. It also happens to have been one of the successes during the Faster, Better, Cheaper times at NASA. George Rieke’s book The Last of the Great Observatories gives the reader a first hand look at the decades of events required to put this telescope into orbit.
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Astrophoto: Van den Bergh 152 by Giovanni Benintende
Go to a public place where people gather such as a rush hour sidewalk downtown or a weekend shopping mall and you’ll quickly notice that each person is an individual with diverse characteristics based on their height, weight and countenance, for example. Such is also true of the stars that congregate above. Each are distinct by size, shape, age, and color. There’s also one other trait that’s immediately noticeable at first glance- each star has a unique brilliance.
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Pan Clearing a Gap in Saturn’s Rings
If you want to understand what causes the gaps in Saturn’s rings, just look at this picture. The bright object in the middle of Saturn’s Encke gap is one of its moons: Pan. The tiny moon is only 26 km (16 miles) across, but its minor gravity can clear out the ring particles. Cassini took this image on October 27, 2006 when it was 385,000 km (239,000 miles) from Pan.
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