View Full Version : May "mapping" of exoplanets be possible?

2006-Oct-07, 01:09 PM
At first the answer appears to be "no", not as long as they, if optically detectable are only "points". Could there be any smart ways to "cheat"? Planets rotation shows us different parts (of course, once they are visible), so their appearance vary. The same may be true for day and night variation and seasons. As photographic tecniques and programming improves, may there be some way to get at least some information about surface("geography", atmospheres, perhaps oceans and icecaps)some day within this century?

2006-Oct-07, 01:23 PM
You can look at our maps of Pluto to see how successful these cheats can be. There was a big improvement in our Pluto mapping after the year or so when Charon was eclipsing it every six days or so. Even so, the map is not very precise.

I wouldn't rule out being able to map exoplanets in the distant future. If we had a Solar-orbiting interferometry array that was millions of miles across, we could potentially map exoplanets within a thousand light years.

2006-Oct-07, 03:20 PM
Given the extreme faintness of any detected planets, I think mapping them according to albedo variations would be very difficult, unless the telescope were truly enormous (I bet an OWL could pull it off). Even if it's possible, the albedo fluctuations may be too subtle--for some planets anyway--to give a statistically significant signal. Pluto has the advantage of having a highly variegated surface.

2006-Oct-09, 07:42 AM
One problem is that we can't actually "see" exoplanets - too faint and drowned out by the star. We can detect these planets through wobbles and other indirect methods. If we can't see it, we can't measure any albedos etc.

2006-Oct-09, 09:53 AM
I had the impression that the OP was asking about the near (this century) future when we start using TPF.

some day within this century?

2006-Oct-09, 11:18 AM
One problem with mapping Earth-like planets is the clouds. In visible light the clouds are the most apparent feature of blue-marble worlds like ours; so any map in visual light would probably be ruined by the white swirls of the atmosphere. There may be ways round this, though.

2006-Oct-10, 06:34 AM
It's an interesting exercise ... we can 'map' Mars to some extent using telescopes right here on Earth (even get some ideas of its weather), and have done so with relatively simple, modest telescopes.

The HST did a lot better, with a telescope with considerably better resolution (and no seeing to contend with).

Can we simply scale the HST up, until we get the angular resolution necessary to 'map' a Mars around stars within 10 pc?

Some issues: what technology could we use to build such a huge mirror? (so maybe we use an interferometric array instead?) how do deal with the glare from the primary?