# Is there a way to tell what the surface of a planet is like?

Kepler-442b

I'm doing a project in which I need to find a planet within our galaxy that might be habitable. I found this planet that is within its stellar system's habitable zone, and due to research I have found that this planet is one of the closest in similarity to Earth, in terms of size, and temperature. But I don't really know anything about the surface or physical features.

I think there is an equation to find if there is life on another planet, but I cant find anything about water...

If you can help me, thank you so much.

I need to know the physical and chemical features on a planet's surface. I know the planet is within the habitable zone and is thought to contain water, but I need more detail, if there is any way to get the specific or at least highly probable features of the surface. Sorry I didn't make this clear enough.

• Are you looking for a methodology to determine what are the physical and chemical properties at the surface of a planet OR are you looking for rule of thumbs to calculate a probability that this planet would have life on it given the physical-chemical properties at the surface of the planet?
– Remi.b
Apr 29, 2015 at 17:04
• There are many popular videos on how to estimate whether a planet is suitable for life or whether life would exist somewhere. They talk about Drake equation (this might be the equation you're talking about although it doesn't allow one to estimate the probability of a planet to sustain life) among other things. Don't forget that Drake equation (and some other work) are highly hypothetical and based on super approximations. To consider them too seriously.
– Remi.b
Apr 29, 2015 at 17:51
• Also don't forget. You must define life first... which is harder than you think. You know about life on earth (carbon and water based) but that doesnt mean that all life in the universe (if there) should be carbon and water based. something to think about..
– Rover Eye
Apr 29, 2015 at 17:51
• Spectroscopy of other planets would tell you a lot about their atmospheres and maybe other conditions, but getting direct light from planets is hard, it's only just now been done for a very close and very large exoplanet.
– user137
Apr 29, 2015 at 21:42
• "I think there is an equation to find if there is life on another planet ..." -- An equation? That seems implausible. May 5, 2015 at 0:24

There is no way at this point in time to tell if Kepler-442b is a big barren rock or a water world or like earth for that matter. They only know it is there because it passes in front of the star it is orbiting and that dims the light. That is the only reason they know it is there.

This planet is not visible.

• +1 though we do know of course the radiation input. But you are correct, that without even a mass measurement we do not know the density or the surface gravity. Or the rotation rate, or anything about the atmosphere or volcanism, or magnetic field... May 14, 2015 at 13:35

By viewing the star and the amount of cycles it went through we can determine what access material are available within its solar system. Next we look at the habitat zone of that star and the size of the planet. It the planet is in the habitat zone then there is a chance for liquid water. If it is also roughly the size of Earth or a little larger it can hold onto some lighter gases that allow us to live on Earth. If the planet is much larger it can hold onto some heavier gases that might make life on the planet impossible. Next given the age of the star and planet we can see how cool the planet has become. A professor at Iowa State University is on the Steering Committee for the Kepler Asteroseismology Research Consortium and he adds that if you want a view of what the surface looks like that it becomes trickier. "We do have some 'maps' from the phase curve of the planet - how the combined brightness changes as the planet goes from primary transit, through quadrature, to secondary transit. If the planet's reflectivity is uneven, that can show up in the light curve if you have enough sensitivity"

• What do you mean by "the size". We know the radius of Kepler-442b, but not its mass. i.e. Its surface gravity is not known. Therefore its atmospheric make up is not known. I'm not sure the age is known either... or is it? May 13, 2015 at 17:44
• By "the size" I mean mass 'm' with the star having mass 'M'. May 14, 2015 at 13:26
• But the mass of the planet is not known... May 14, 2015 at 13:31
• We might in time by Transit photometry and Radial velocity. If we know for sure that it is the only planet around that star then we can use the Rad. velocity approach, otherwise we need to wait for transit photometry to verify the other planets. May 14, 2015 at 13:44

I think the methodologies you're asking for are still very much being worked out (and you might want to think of this as looking for a model rather than an equation -- the latter is too simplistic). It might be best to find some relevant articles (starting with some that are geared to the layman) and work from there:

It is possible that the basic colouration of the visible surface would lead you to some conclusions - the presence, or otherwise, of clouds for example.

Maybe filtering the light through a diffraction grating would give you some idea of the atmosphere or surface's constituent elements.

If you have some serious kit, you could wait and hope that the planet passes in front of either a background star, or it's own 'sun' - the change in the spectrum of that light pre and during the occultation could reveal information about the atmosphere too. That's a bit of a long shot, though!

I hope that is useful in some way.

OSH.