The greatest disappearing act

So where did Saturn’s rings go? Dave Heller and Astronomer Derrick Pitts talk about the disappearing act that we can see every 15 years as the planet, and us on Earth, orbit the sun.

50 thousand years ago a meteor hit the earth creating a crater a mile wide, but we haven’t had anything of that magnitude since then. The meteor most likely to come closest to earth in 40 to 50 years is 260 foot in size, and will have an impact ten times the atomic bomb that hit Hiroshima… but before you run for cover there is only a 1 in 3000 chance of hitting earth. Also where did Saturn’s rings go? It’s 29.5 yr. orbit and 27 degree tilt allows us to see the disappearing act every 15 years as it and we orbit the sun. 400 years ago today Galileo was turning the spyglass into an astronomical research tool. Might even have been today that he made his first presentation to the Venetian court, promoting sales of his new device.
Credit: NASA, ESA and E. Karkoschka (University of Arizona) from Hubblesite.org

Listen:
[audio: st20090817.mp3]