Space facts? Oh, I've got a bunch! <img src="/images/icons/wink.gif" /> I love trivia!<br /><br />* The Sun comprises about 99% of the mass of the entire solar system. Most of the remaining 1% is Jupiter.<br /><br />* Pluto and Charon are the only bodies known to be mutually synchronous -- they always face the same side towards one another. That means that a Pluto day is the same as Charon's orbital period, which is the same as Charon's day. Charon is fixed to one position in Pluto's sky, and although it goes through phases just like our moon, it doesn't change its face, although the stars (and the distant Sun) wheel past behind it.<br /><br />* The Moon is tidally locked with the Earth -- it rotates synchronously. One lunar day is exactly one lunar month long (29.53 days). Because of this, a stationary observer on the Moon can never see an Earthrise. (If you're in orbit, however, you can see an Earthrise.)<br /><br />* The Earth has been photographed many, many times, but only occasionally from a spacecraft not orbiting around it or the Moon. The most distant photograph ever taken of the Earth was taken on Valentine's Day, 1991 by the Voyager 1 spacecraft, at a distance of over 3 billion miles. The Earth is less than a single pixel, only perceptible after the image has been computer enhanced.<br /><br />* One of the surprises from the Cassini mission is Iapetus. The astronomer Giovanni Cassini, who discovered the moon, observed that he could only see Iapetus on one side of Saturn. He deduced that it must be bright on one side and dark on the other. The Voyager mission proved him right, but did not settle the question of "why". Cassini has now taken enough pictures to show that the dark material is a thin layer on top of bright white ice -- but has revealed a completely different mystery as well. There is an enormous ridge around the equator of Iapetus, standing at least 13 km high in places, and spanning 20 km. Nobody knows how it came to be.<br /><br />* Dr Kar <div class="Discussion_UserSignature"> <p> </p><p><font color="#666699"><em>"People assume that time is a strict progression of cause to effect, but actually from a non-linear, non-subjective viewpoint it's more like a big ball of wibbly wobbly . . . timey wimey . . . stuff."</em> -- The Tenth Doctor, "Blink"</font></p> </div>