July 12, 2010
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From Cassini, 1,460,000,000 km away, comes this great image of the majestic rings of Saturn lit up brightly by the Sun. This is a raw image, it hasn’t been processed, that spot in the middle of the image is probably a cosmic ray hit.
Saturn’s rings are not a simple disk, but it is actually made up of thousands of separate rings. The big dark gap in the rings is called the Cassini Division, discovered by the astronomer Giovanni Domenico Cassini in the 17th century. Saturn’s moon Mimas is responsible for that gap; any particle in the Cassini Division orbits Saturn in half the time Mimas does, and so it feels a periodic tug from the moon (called a resonance). That pulls the particles clear from that region, carving a gap. Other broad gaps in the rings are from other moon resonances, while some of the narrow ones are from small moons in the gaps gravitationally clearing out nearby ring particles.The rings are made up of icy particles,they range in size from, about a grain of sand to the size of a small house, but on average they are the size of your clenched fist. The rings extend from about 74,000 kilometres to about 180,000 kilometres from Saturn’s centre, but they are very thin, less than a hundred metres thick! A scale model of the rings as thick as a single piece of tissue paper would cover an entire football field! It’s still unclear how Saturn, or the other three gas giants, got their rings, but there is more than one mechanism to get them, a moon could get hit by an asteroid or comet shattering it.
There’s a lot we don’t know about Saturn and its rings, but Cassini has been orbiting Saturn for a while, it’s taken some amazing images of Saturn and everything around it. Cassini is helping us solve the mysteries of the Saturn and its surroundings in far better detail than ever before. It has produced some of the highest resolution images of the ringed planet and its moons.
You can scour the Cassini image gallery yourself, click here.
June 23, 2010
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Awesome! This is amazing picture of M66 comes from the Hubble Space Telescope. Spiral galaxies are so beautiful and M66 is no exception. It’s as big as the Milky Way and it’s 35 million light years away.
Head down to Bad Astronomy where the Bad Astronomer takes an artistic look at this image and covers all the details.
From Doug Wheelock’s Twitpic page, an astronaut on the International Space Station (ISS), comes this brilliant image of the Southern Lights (Aurora Australis) as seen from the ISS.
The northern (Aurora Borealis) and The southern (Aurora Australis) are caused when the charged particles (ions) from the Sun hit the Earth. The ions from the Sun excite the electrons of the atoms in the atmosphere which in turn emit a photon (light). Different atoms release light in different colours, the greenish colour seen here is emitted by oxygen atoms.
Doug Wheelock has some out of this world pictures on Twitpic page, check it out!