Questions tagged [exoplanet]

Questions regarding planets that lie outside the Solar System.

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55
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3answers
8k views

Where did TRAPPIST-1a go?

According to the NASA announcement and the Wikipedia article on TRAPPIST-1, the planets around the TRAPPIST-1 star are named TRAPPIST-1 b through h. What happened to "TRAPPIST-1 a"?
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Is it odd that our Sun has so many planets?

The internet is abuzz with the new evidence of the possible ninth planet in our Solar System. With those nine objects, the asteroid belt, the Kuiper belt, and everything else in our Solar System - the ...
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If Alpha Centauri A's solar system exactly mirrored our own, what would we be able to detect?

Suppose there was an exact replica of our solar system 4.4 ly away (people included). What would we be able to detect and with what telescope(s)? Which planets? Could we detect radio transmissions and/...
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2answers
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Which of the planets would be detected if they were exoplanets?

An (almost-)omnipotent being selects the solar system, presses Ctrl+C, and then Ctrl+V several times, creating copies at distances of 5, 500, 50.000, and 5.000.000 light-years away. All in a direction ...
25
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2answers
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Is Jupiter still an anomaly?

I remember a few years ago hearing that Jupiter was an anomaly in the landscape of exoplanets. Back then, most Jupiter-mass planets discovered were Hot Jupiters, orbiting very close to their host star....
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4answers
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Is there any planet bigger than a star?

Or a star smaller than a planet? Which star and planet would be an example of this?
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3answers
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how far away could we detect that Earth has life?

My guess is that life bearing planets are too far apart to be detected. I think we can only find the ones within a sphere around our planet that is 100s of light years in diameter but I suspect life ...
24
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1answer
274 views

How are the compositional components of exoplanet atmospheres differentiated?

How are exoplanetary atmosphere compositional spectra distinguished from those of the parent star(s), from the composition of the planetary surface or any other factor? Is it actually possible to ...
24
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3answers
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Terrestrial Exoplanet Skies – I've Built a Visual Sky Chart. Is it Accurate?

I'm an artist (and science enthusiast) and I've been trying to find a comprehensive resource that would help me clearly identify likely sky colors (as perceived by human vision) for exoplanets that ...
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10answers
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Is the closest planet to another planet always the innermost planet?

In our Solar system Mercury is not only the closest planet to Earth on average but also, for the same reason, the closest planet on average to all other planets (Jupiter, Neptune, etc...). Does that ...
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How was Trappist-1 discovered?

I was going through all the questions in this community related to TRAPPIST-1 in order to know how planets TRAPPIST-1b to TRAPPIST-1h were discovered, but there aren't any. How were they discovered?
20
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1answer
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Why are most discovered exoplanets heavier than Earth?

Looking at all discovered exoplanets (4393 exoplanets), I found than only 17 of them (less than one percent!) have masses less or equal to Earth's mass. Why so? Is it because it is very difficult to ...
20
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2answers
857 views

Hypothetical trans-Neptunian planets orbiting the Sun

The planet HD 106906 b was found at 650 AU from its home star, a star not so different from the Sun. Fomalhaut b is also a young planet that is orbiting very far away from its star. These two planets ...
20
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1answer
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How many sun-like stars are there in the universe?

After yesterday's announcement of the Kepler telescope finding a huge amount of newly observed exoplanets, i saw a headline claiming that as much as 22% of sun like stars in the universe have planets ...
19
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6answers
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What does forward modeling mean?

In my research on exoplanets, I have heard many people talk "forward modeling of exoplanet atmospheres". I don't know what the "forward" means in "forward modeling" and how it compares with "reverse ...
19
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2answers
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Is there a gas giant orbiting TRAPPIST-1?

I would like to know if besides these planets, astronomers have discovered a gas planet like Jupiter in this system and if on these planets could exist life without a comet protector like Jupiter does ...
19
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3answers
650 views

What practical considerations are there for amateur observations of transiting exoplanets?

Obviously, I am not referring to actual viewing of the exoplanets themselves, but detecting their effects on the brightness of the light emitted from the parent star (as in the diagram below from The ...
19
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2answers
536 views

How hot can a planet be?

Given that some exoplanets, particular "Hot Jupiters", orbit very closely to their parent star, how hot can these planets become? What is the hottest exoplanet discovered so far?
18
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4answers
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What is the most extreme weather found on another planet?

On Venus, there is really inhospitable weather, as well as within the gas giants in our solar system. Are there examples of even more extreme weather on planets found in other solar systems than ours?
18
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1answer
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Exoplanet dip in transit light curve when the planet passes behind the star

In the animation below, I don't understand why the brightness slightly decreases when the planet is behind the star. Where does this effect come from?
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2answers
439 views

Do any known exoplanetary/solar bodies have "annular" eclipses similar to Earth's?

This was somewhat inspired by this question but is a bit different: I am interested in if there are any known systems in which the angular size of the eclipsing object is almost the same as the ...
17
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3answers
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Do celestial objects need to be big to have liquid water on their surfaces?

I mean no asteroid, planetoid that I am aware of has water on its surface. It is way more common to see ice in it. So I figured that the size of the celestial body has something to do with the cycle ...
17
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1answer
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What is the current accepted theory for the fate of hot Jupiters?

It is well established that one main feature of many hot jupiters is their close proximity to their parent star, usually the equivalent of being within the orbit of Mercury. So, these planets are gas ...
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2answers
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Is it possible for planetary rings to be perpendicular (or near perpendicular) to the planet's orbit around the host star?

Is it possible for planetary rings to be perpendicular (or near perpendicular) to the planet's orbit around the host star?
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4answers
850 views

How would we detect an Earth doppelganger planet?

With our current technology, or technology available in the near future (up to 2025), how would we detect a planet exactly like our own, and how close would it have to be to be detectable? Which ...
16
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2answers
910 views

Statistics of elements abundance in exoplanets

Recently, I encountered the concept of carbon planets - planets, which would be, unlike the Earth, formed mostly by carbon, instead of oxygen, silicon and magnesium. (I am not counting iron, which is ...
15
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4answers
489 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 ...
15
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2answers
448 views

What percent of planets are in the position that they could be viewed edge-on from Earth? (and thus able to undergo transits)

Star number 12644769 from the Kepler Input Catalog was identified as an eclipsing binary with a 41-day period, from the detection of its mutual eclipses (9). Eclipses occur because the orbital ...
15
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1answer
733 views

Is the surface of TrES-2b actually dark?

The exoplanet TrES-2b is known as the darkest planet ever found, reflecting <1% of the light that hits it. What does it mean in respect to the surface? What would we see below the atmosphere of ...
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3answers
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Is the measurement of distance and position of remote celestial bodies accurate?

Considering that light is affected by gravity, how accurate are measurements of distant stars and galaxies? When light passes through objects with great mass, such as Jupiter size planets, stars, or ...
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4answers
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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 ...
14
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1answer
510 views

Is it possible for a moon to orbit a planet floating free in the galaxy rather than orbiting a star

This article got me thinking, can a planet hold a moon in orbit if it is just floating in the galaxy by itself not as part of a star system? Can a celestial body even qualify as a planet if it is ...
14
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1answer
433 views

Orbital velocity of a planet - why is my calculation off by about 10%?

I am not sure if I am doing something wrong, or misunderstanding Reider and Kenworthy (2016). I'm just trying to reproduce the orbital velocities listed in Table 1. The second paragraph of Section II ...
14
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1answer
262 views

How close are we to having the technology to measure planetary obliquity for exoplanets?

As far as I can tell, we do not yet have the precision to even put reasonable bounds on an exoplanets obliquity, but wikipedia seems to indicate that this may be possible in the "near future." It ...
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3answers
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Are there any planets or moons denser than Earth?

Earth has the highest density out of all planets, planetoids and moons of our planetary system, and also has a higher density than the Sun. Do we know any exoplanets or moons denser than Earth?
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What is the orbital path of the newly discovered star-less planet PSO J318.5-22?

Recent results from Institute for Astronomy at the University of Hawaii at Manoa claim that there is a Jupiter-sized gas giant planet that is independent of a star about 80 light-years from Earth. ...
13
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1answer
974 views

How is an exoplanet characterised as "Earth-Like"?

Which features or characteristics are taken into account to characterize an exoplanet as "Earth-Like"?
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2answers
502 views

The battle over Gliese 581 and Gliese 667C?

In 2014, Robertson et al. made a case that stellar activity is masquerading as planets (here and here) for these well-known systems. In both cases, they claim that the only real planets discovered so ...
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5answers
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Why there are no terrestrial planets with a subsurface ocean?

Subsurface oceans in satellites are pretty common: Europa, Enceladus, Ganymede, Callisto, maybe Pluto... This is due to tidal heating of their host planet, Jupiter and Saturn, which heats up the inner ...
11
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2answers
259 views

How do we know that an exoplanet is tidally locked to the parent star?

Often in discussing exoplanets we hear that they are close to the parent star (usually a red dwarf) but then there's a caveat that the planet is tidally locked to that star and that that fact severely ...
11
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1answer
264 views

Could the James Webb Space Telescope detect biosignals on exoplanets?

The James Webb Space Telescope (JWST) which is slated to launch in 2018 will bring us a better view of exoplanets, but will it be sufficient to detect signs of life on at least some of those worlds? ...
11
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0answers
286 views

Method to determine the amount of reflected starlight necessary for an exoplanet to be visible from a given distance/angle? [closed]

What is the method to determine the amount of reflected starlight necessary for an exoplanet to be visible from a given distance/angle? (Not from occlusion but actually visible on its own.) Further, ...
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4answers
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Why can't we build a huge stationary optical telescope inside a depression similar to the FAST?

So first we'll have to find a natural depression or we should create one. I understand you can only see a single portion of the sky since it can't be moved, so my money is on creating an artificial ...
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4answers
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Are stars near the ecliptic the only stars from which Earth would appear to transit the Sun?

The majority of exoplanets we have discovered have been found by the transit method, in which a planet passes in front of its parent star and by analyzing the light curve we can deduct its ...
10
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2answers
702 views

Which is the closest exoplanet to Earth?

The closest star to Earth (after the Sun) is well-known: Alpha Centauri, 4.3 light years away. But what about the closest exoplanet to Earth, outside of the Solar System?
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1answer
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What is sin i in this graph and why is it there?

This is some data presented in a lecture on exoplanets that depicts the distribution of the sizes of super-Earths in comparison to the mass of Jupiter. I would like to know what the argument of the ...
10
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2answers
3k views

Is it possible that the Sun has a binary partner (the Nemesis Theory) that has eluded detection? [duplicate]

I just recently learned about the theory that our Sun has a small companion star with a 26 million year orbit. This theory came about when it was realized that mass extinction events happened ...
10
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1answer
479 views

What are the challenges in finding Earth-like planets via the radial velocity method?

[I have re-asked this, because it was a good question by @Banyan, which was deleted whilst I was composing an answer.] Most exoplanets that are found by the radial velocity ("Doppler wobble")...
10
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1answer
322 views

How to find Exomoons?

How would we be able to detect Exomoons? We detect exoplanets by seeing if the light gets faint from a star, but could we really use the same method for determining if there is an exomoon around that ...
10
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1answer
313 views

Is there any way a planet could form independent of a star?

I just recently heard that there are currently no theoretical models that support planet formation without a star, but I can't remember where. So, I thought I would request all of your expertises. ...

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