View Full Version : New moon rising

07-22-2007, 04:35 AM
At what point does a moon become a rock?

07-22-2007, 02:28 PM
It's 1.2 miles wide. That's, like, nothing. That's the distance
I walk to the gas station to get a snickers. You know, if I
were an authority in Astronomy or whatever, I'd make a
rule that says that something has to be at least a certain
percentage of the planets' size before it can be called a moon.

wtf happened to adrianxyz?

07-22-2007, 04:37 PM
Do you think there should be an upper limit, too? Charon (http://en.wikipedia.org/wiki/Charon_(moon)) is a large percentage of the size of Pluto (http://en.wikipedia.org/wiki/Pluto). It's debatable whether they are a binary system (http://en.wikipedia.org/wiki/Binary_system_%28astronomy%29) or minor planet (http://en.wikipedia.org/wiki/Minor_planet)/moon (http://en.wikipedia.org/wiki/Natural_satellite) system. (I sound like a Wikipedia entry myself . . . . :) )

07-23-2007, 12:24 AM
It's quite clear that the ancient terminology of "planet" and "moon" are now inadequate (re the debacle over reclassifying Pluto).

For me, we have
- 4 terrestrial planets (Mercury, Venus, Earth, Mars)
- Rocky dwarfs (Ceres and the rest of the asteroid belt)
- 4 gas giants (Jupiter, Saturn, Uranus, Neptune)
- Icy dwarfs (Pluto and the rest of the KBO's (http://en.wikipedia.org/wiki/Kuiper_belt))
- eccentric orbit objects like comets
And that's just the things in orbit around the Sun.
Add in things in orbit around "planets" and orbits around each other, and it needs a re-think IMO.

I also think that naming every last pebble in orbit is just a waste of time as well just because of what it happens to be in orbit around. All the similar sized rocks in the asteroid belt don't have names. Until someone actually lands a person / probe on one of these things then they should just remain as catalog entries in some database.

Certainly, the discovery rate of NEO's (http://en.wikipedia.org/wiki/Near-Earth_object) (several every day) is such that it would be futile to even attempt naming all of them, except for perhaps the ones which are really interesting (a bit too near).

It's like seeing a forest for the first time and basing the entire naming system on the first few trees you see. Only to discover there are actually more trees than you can count, the population of trees isn't stable, there are many different species which could be trees, and there are lots of other things which definitely aren't trees.