A new photograph from the Spitzer Space Telescope shows how supernova remnant Cassiopeia A evolved over time. The original star contained 15 to 20 times the mass of our Sun, and was made up of concentric shells of elements. The lightest elements, like hydrogen, were in the outermost shell, while the heaviest elements sunk to the centre. The shells of exploded material match up quite well with the original layers in the star before it detonated as a supernova.
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It Took More than an Asteroid to Kill the Dinosaurs
How did the dinosaurs die? It’s a question scientists have been trying to figure out since their fossils were first discovered. Most believe that it was a giant asteroid that stuck the Yucatan peninsula 65 million years ago, and ended the dinosaurs’ reign on Earth. But evidence is mounting that the asteroid strike might have just been the final killing blow. The previous 500,000 years were unpleasant too, with multiple meteor strikes, severe volcanism, and rapid climate change.
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Bacteria Found Deep Underground
Princeton researchers have discovered a colony of bacteria that lives more than 3 km (2 miles) underground. This bacteria lives completely cut off from the biosphere on the surface of the Earth, and derives its energy from the radioactive decay of rocks underground. By finding life in these extreme conditions, scientists are expanding their understanding of what kinds of habits can support life.
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Gaps in Saturn’s Rings
This Cassini image shows the dark gaps in Saturn’s A ring, which are caused by a collection of moons. Even though these moons max out at a few dozen kilometres across, they have enough gravity to pull particles out of the ring orbit as they pass by. Cassini took this photograph on September 11, 2006 from a distance of 1.1 million kilometers (700,000 miles) from Saturn.
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Baby Galaxies Weighed by Spitzer
Astronomers have discovered two of the most distant galaxies ever seen, when the Universe was only 700 million years old. The galaxies were first discovered as part of the Hubble Space Telescope’s Deep Field Survey, which looked into the distant Universe. Astronomers then did follow-on observations with the Spitzer Space Telescope to confirm their distance and age. The galaxies are thought to be between 50-300 million years old, and have only 1% of the mass of our own Milky Way.
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Young Star Grows Up Quickly
New images from the Japanese Subaru telescope show how a nearby young star ended its infancy rapidly. The star, called HD 141569A, has a hole in the disc of gas and dust surrounding it. Astronomers think that the star rapidly ionized its surrounding gas, and then pushed it away with its intense solar radiation. The gap is located about the same distance from the star as Saturn’s orbit, and it lends additional evidence to theories about how discs of material evolve around young stars.
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Spirit Celebrates 1,000 Days on Mars
NASA’s Spirit Mars Exploration Rover recently celebrated its 1000th day on the surface of the Red Planet. To celebrate the occasion, NASA used the rover to capture a full 360-degree panorama view of Mars from its vantage point. The rover has been perched on the side of a hill for the last few months, to ride out the Martian winter’ reduced light. Spirit and Opportunity were both expected to only last 90 days on the surface of Mars.
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MESSENGER Heads Past Venus, Next Stop: Venus
NASA’s MESSENGER made its closest approach to Venus today, coming within 2,990 kilometers (1,860 miles) of its surface. The spacecraft used this close encounter with Venus’ gravity well to alter its trajectory as it travels towards its final destination: Mercury. This won’t be its final encounter with our twin planet, though. MESSENGER will meet up with Venus again in June 2007. It’ll finally make its first encounter with Mercury in January 2008, but won’t be in a final orbit until 2011.
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Nearly a Thousand Years After the Death of a Star
In 1054 A.D., Chinese astronomers recorded the temporary brightening of a star in the constellation Taurus. Nearly 1000 years later, we look in the same region and see the exploded remnants of a dead star: the Crab Nebula. This composite photograph of the Crab Nebula was made by merging images from Hubble, the Chandra X-Ray Observatory, and the Spitzer Space Telescope. It shows only a hail of high-energy particles and expanding debris cloud that once was a massive star.
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Globular Clusters Sort their Stars
Globular clusters are regions of space where stars are densely packed together – 10,000 times more dense than our local stellar neighbourhood. New evidence from the Hubble Space Telescope has shown that globular clusters will sort out themselves out, hoarding more massive stars in the centre, and pushing the less massive stars out to the edges. Hubble captured images of globular cluster 47 Tucanae for nearly 7 years, allowing astronomers to carefully plot the positions of stars moving in the cluster, and then calculate how close they were to the centre.
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