Questions about solar system planets/moons and exoplanets that exhibit similar features to the Earth.

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13
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2answers
2k views

How many planets have we discovered that can support human life?

I have heard a lot of buzz about distant planets that could potentially be second homes for human existence, but what is that approximate number?
13
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4answers
239 views

When will we be able to detect Earth-sized exoplanets?

I have heard that the only planets able to be seen outside the Solar system are Jovian-sized planets with the occasional detection of planets three times the Earth's size. But, as far as I know, we ...
9
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2answers
116 views

What are the Earth-like features of Titan?

This NASA site says that hidden beneath the smog of Titan are Cirrus like clouds and This space article describes how Titan's atmosphere is similar to Earth's too. What other features does Titan ...
8
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3answers
3k views

If Venus and Mars changed places, would we then have 3 habitable planets?

This is the supposition: Venus is too hot, Mars is too cold. If they switched places then Solar energy would change to make both more Earth like. We might as well have had three instead of just one ...
8
votes
1answer
352 views

Could there be Earth-like planets in binary or trinary systems?

Could Earth-like (suitable for Human habitation) planets exist in systems with 2 or 3 suns, have any been found? With more than a single star, isn't it likely that the habitation zone would be too ...
7
votes
3answers
169 views

Why Earthian atmosphere is so thin?

Venus is somewhat lighter then Earth, yet has a much thicker atmosphere. One would imagine that the following should be true: During the formation phase, all inner planets had captured as much gas ...
6
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2answers
147 views

Can we find out whether early Venus was Earth-like or not?

It has been speculated that Venus billions of years ago could've had a much different atmosphere with liquid water on its surface and possibly life. Partly thanks to the cooler young Sun. But is it ...
6
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2answers
450 views

Why is carbon so rare on the Moon and on Mars?

Carbon is the fourth most common element in the universe and in the Solar system. It is about the ninth most common element in Earth's crust. It doesn't seem to be part of any of the ten most common ...
6
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2answers
565 views

What is the maximum number of planets in the habitable zone?

At present, it seems like we are alone in our solar system. How many earth-like planets would fit into the habitable zone of the solar system? The orbits should be stable for quite a time, i.e. for ...
5
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4answers
1k views

Would an exoplanet without axial tilt have no seasons?

Would an Earth analog exoplanet which rotates around a solar analog, but without axial tilt, have no seasons? Would it be similar to how Los Angeles does not have very noticeable seasons compared to ...
5
votes
1answer
521 views

How small can a planet be and still have Earth-like gravity?

A planet made from denser material than Earth might have equal gravity to Earth but a smaller radius. How small can a planet be and still have Earth gravity? Ideally it should be habitable by humans, ...
5
votes
1answer
106 views

How small a star can provide Sun-level illumination to its planets?

...or how small can a solar system be, to sustain an Earth-like planet? Sun is not really small, and 1AU is pretty far when you look at orbital radii of exoplanets and size of their stars. How small ...
5
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1answer
108 views

How should exoplanet discoveries affect SETI?

Given that SETI was created before the discovery of exoplanets, has this changed how they search? Would it make more sense to focus efforts on discovered earth like exoplanets?
5
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1answer
87 views

Is it conceivable that the presence of chlorophyll (or similar) could be distinguishable from other chemicals on an exoplanet?

If an Earth-like exoplanet had a sufficiently extensive plant biosphere (i.e large forests, aquatic algal mats etc), is it at all conceivable that scientists could spectroscopically detect the ...
5
votes
3answers
195 views

Galactic Habitable Zone

Do galaxies have habitable zones the same as stars do? Say in a galaxy with a very active nucleus producing a lot of heat and radiation, would there be a point at which no star's planets could harbor ...
4
votes
1answer
61 views

Sun as our Supergiant

Let's talk about the time when our sun becomes a supergiant. We know that our solar system may get destroyed or it may get affected due the large mass of the supergiant and also due to the large ...
4
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2answers
209 views

Help in determining the features of an unusual, fictional star system

(Hope this is the right Stack-exchange site for this question) I'm working on a sci-fi RPG campaign, set on a very atypical location. Since this is a work of fiction, there's enough room for ...
4
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1answer
79 views

How did pre-Earth's mass and orbit change at the Moon formation event?

The popular, but still disputable, Moon formation theory is that a pre-Earth was hit by a Mars sized planet. The mass ratio of Earth:Mars:Moon is roughly 100:10:1. Does this mean that pre-Earth was ...
3
votes
1answer
733 views

What would be the dynamics of a double-planet system, similar to Earth / Moon, but with both bodies nearly Earth-sized?

Researching a sci-fi story involving a "twin-planet" system. Is such an arrangement (however unlikely) physically possible? And if so, must they be tidally locked with each other, similar to the moon, ...
2
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2answers
105 views

Could we detect an earth-like planet around another star?

Could we detect an earth-like planet (e.g. similar distance from star, and similar size) with current planet finding techniques? If an earth-like planet were orbiting our nearest star, excluding the ...
2
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2answers
116 views

How do scientists know if an Earth-like planet is really Earth-like?

I'm not sure how scientists determine that a planet is really an Earth-like planet. How do they do it?
2
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0answers
93 views

Landing on an “earth-like” planet (practical application)

This may not belong here in astronomy and my apologies if that's the case. The hypothetical: We find, and are able to travel to (in a reasonably short amount of time), a planet that is for all intents ...
1
vote
1answer
77 views

How significant is a planet's density to the formation of life?

I'm doing some writing set on a fictional earthlike planet that for reasons needs to be substantially larger than Earth but can't have substantially higher gravity. I've been able to compromise with a ...
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3answers
44 views

Does more ocean on an Earth analog produce a different rotation period?

Would an exoplanet that has more ocean than Earth rotate at a different speed as a result of this? Would the amount of water impact the weight, gravitational pull, and/or tidal forces and cause a ...
0
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1answer
46 views

Sources of astronomy-related dataset?

I'm doing a project for a statistics class, and I thought it may be interesting work with a dataset associated with astronomy. I know absolutely nothing about astronomy, unfortunately, and I wouldn't ...
0
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1answer
112 views

Collision of two Earths

Assume that two Earth-like planets orbited the same star, with elliptic orbits. Eventually, something occurs that caused the two planets to collide. What would be the outcome of such a catastrophe? ...