<p>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"</p>

CC BY-SA 3.0
2015-05-13T17:44:14.680Z
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?
ProfRob
CC BY-SA 3.0
2015-05-14T13:26:34.877Z
By "the size" I mean mass 'm' with the star having mass 'M'.
Matthew Kruse
CC BY-SA 3.0
2015-05-14T13:31:21.753Z
But the mass of the planet is not known...
ProfRob
CC BY-SA 3.0
2015-05-14T13:44:49.843Z
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.
Matthew Kruse
CC BY-SA 3.0
2015-05-13T14:20:27.060Z
2015-05-13T14:20:27.060Z
Matthew Kruse
<p>The answer to your question for that specific planet is No. </p>

<p>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. </p>

<p>This planet is not visible.</p>

CC BY-SA 3.0
2015-05-14T13:35:37.010Z
+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...
ProfRob
CC BY-SA 3.0
2015-05-09T22:26:59.803Z
2015-05-09T22:48:00.333Z
2015-05-09T22:48:00.333Z
Little Kobold
<p>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 <em>model</em> rather than an <em>equation</em> -- 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:</p>

<p><a href="http://www.universetoday.com/104652/how-do-you-find-the-signs-of-life-in-alien-planets/" rel="nofollow">http://www.universetoday.com/104652/how-do-you-find-the-signs-of-life-in-alien-planets/</a>
<a href="http://www.planetary.org/explore/space-topics/exoplanets/direct-imaging.html" rel="nofollow">http://www.planetary.org/explore/space-topics/exoplanets/direct-imaging.html</a>
<a href="http://www.nasa.gov/press-release/goddard/nasa-giss-to-help-lead-search-for-habitable-exoplanets" rel="nofollow">http://www.nasa.gov/press-release/goddard/nasa-giss-to-help-lead-search-for-habitable-exoplanets</a>
<a href="http://astrobites.org/2012/11/11/detecting-exoplanet-atmospheres-from-the-ground/" rel="nofollow">http://astrobites.org/2012/11/11/detecting-exoplanet-atmospheres-from-the-ground/</a>
<a href="http://phys.org/news/2014-07-earth-exoplanet-life-visible.html" rel="nofollow">http://phys.org/news/2014-07-earth-exoplanet-life-visible.html</a></p>

CC BY-SA 3.0
2015-05-05T14:47:21.267Z
2015-05-05T14:47:21.267Z
blamblambunny
<p>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. </p>

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

<p>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! </p>

<p>I hope that is useful in some way. </p>

<p>OSH.</p>

CC BY-SA 3.0
2015-05-07T14:57:39.883Z
2015-05-07T14:57:39.883Z
OnlySteveH
<p>Kepler-442b</p>
<p>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 in terms of size and temperature, this planet is one of the most similar to Earth. I don't really know anything about the surface or physical features.</p>
<p>I think there is an equation to find if there is <em>life</em> on another planet, but I can't find anything about <em>water</em>.</p>
<p>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.</p>

CC BY-SA 3.0
2015-05-05T00:24:42.540Z
"I think there is an equation to find if there is *life* on another planet ..." -- An equation? That seems implausible.
Keith Thompson
CC BY-SA 3.0
2015-05-06T15:55:57.123Z
Its called the Drake equation
Nathanael Smith
CC BY-SA 3.0
2015-05-06T17:18:46.390Z
The way you described it, I thought you meant that there's an equation that will tell you whether a particular planet has life or not. The Drake equation doesn't do that. All it does is provide an estimate (given a number of assumptions you have to plug into it) of how many communicative extraterrestrial civilizations currently exist in this galaxy. http://en.wikipedia.org/wiki/Drake_equation
Keith Thompson
<planet><observational-astronomy>
Is there a way to tell what the surface of a planet is like?
Nathanael Smith
# Is there a way to tell what the surface of a planet is like?

(Asked by: username_0 on 2015-04-29)

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 in terms of size and temperature, this planet is one of the most similar to Earth. 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 can't find anything about *water*.

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.

**Tags:** planet, observational-astronomy

> **Comments:**
> **username_1**: "I think there is an equation to find if there is *life* on another planet ..." -- An equation? That seems implausible.  
> **username_0**: Its called the Drake equation  
> **username_1**: The way you described it, I thought you meant that there's an equation that will tell you whether a particular planet has life or not. The Drake equation doesn't do that. All it does is provide an estimate (given a number of assumptions you have to plug into it) of how many communicative extraterrestrial civilizations currently exist in this galaxy. http://en.wikipedia.org/wiki/Drake_equation  

---

## 4 answers

### Answer by username_2 on 2015-05-13. Score: 4

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"

> **Comments:**
> **username_3**: 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?  
> **username_2**: By "the size" I mean mass 'm' with the star having mass 'M'.  
> **username_3**: But the mass of the planet is not known...  
> **username_2**: 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.  

---

### Answer by username_4 on 2015-05-09. Score: 4

The answer to your question for that specific planet is No.

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.

> **Comments:**
> **username_3**: +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...  

---

### Answer by username_5 on 2015-05-05. Score: 1

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:

<http://www.universetoday.com/104652/how-do-you-find-the-signs-of-life-in-alien-planets/>
<http://www.planetary.org/explore/space-topics/exoplanets/direct-imaging.html>
<http://www.nasa.gov/press-release/goddard/nasa-giss-to-help-lead-search-for-habitable-exoplanets>
<http://astrobites.org/2012/11/11/detecting-exoplanet-atmospheres-from-the-ground/>
<http://phys.org/news/2014-07-earth-exoplanet-life-visible.html>


---

### Answer by username_6 on 2015-05-07. Score: 1

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.


---

