Is there a distance at which a satellite will orbit a body indefinitely? Is this distance a universal constant? [more inside]
posted by doublehappy on Oct 16, 2009 - 28 answers

Planetary magnetic fields and life: Is there any reason to believe that strong magnetic fields on rocky inner planets are relatively uncommon? [more inside]
posted by leotrotsky on Jul 27, 2009 - 13 answers

Why hasn't anyone invented cheap space probes? Some kind of thing that could be sent up en mass to gather just base data we don't have on all the planets/moons/etc . . .? [more inside]
posted by [insert clever name here] on Aug 18, 2007 - 34 answers

I want to buy my son, who is turning six, a telescope for his birthday. I don't want to spend a fortune, but one site I looked at for advice said anything less than $300 is a piece of junk. Anyone have any advice (including specific models) on one I can by this budding astronomer for $100 or less?
posted by alexg23 on Jul 25, 2005 - 22 answers