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Questions tagged [planet]

Questions regarding astronomical bodies orbiting stars which are of proper size to be called planets.

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Which planet gets the most money? Which gets the least?

I'm curious if anyone has ever tallied the expenditures of all of the world's space programs, and then tried to divide it by which planet was targeted. It's possible this has already been done. If ...
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Elliptical orbits transformed to “equivalent” circular orbit

I'm trying to transform Mars' elliptical orbit into its circular "equivalent". I understand that if the semi-major axis is used as the radius, and the mean angular rate and period are kept the same, ...
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Saturn's tropical year [closed]

What is the value of Saturn's "tropical year" (as opposed to its "sidereal year"). I am seeing it listed as 10 days shorter (10,747 days) than the sidereal year (10,759 days). How could this be if ...
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Calculate the state vector of planets and moons

What is the efficient way to calculate the state vector of planets and moons? The coordinate system for planets would be with center in Solar System Baricenter, for Moon- with center in Earth and in ...
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Are there planets that are tide-locked to their sun?

An interesting question was raised about satellites being tide-locked (Does a satellite naturally turn in phase with its orbit, always facing Earth?). It was a educational read for me, and in one ...
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Do any planets other than Earth have artificial satellites?

Space probes have been sent to fly by or temporarily orbit other planets. Have any artificial satellites been sent to permanently orbit another planet and record data? "Permanent" as in purpose of ...
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208 views

Is there a planet walk with the positions of Voyager 1 and 2?

There are a lot of walks like the Sagan Planet Walk (see the list on Wikipedia). But are there any of these walks that include the position of the Voyager space probes? Some days ago I was ...
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Could a Uranus-style planet tidally lock?

I was reading this world building post and it got me thinking - every body eventually tidally locks with the body it rotates with. Let's say for a moment a planet near the sun had a Uranus style axis ...
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Why is Jupiter called a “Gas Giant”?

Jupiter's enormous gravity would turn its atmosphere first into a liquid from a certain depth, and then into a solid further towards its centre. So Jupiter has a solid core, above which is a liquid ...
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Does Sunlight have a range? [closed]

If you switch on a lightbulb in a room its light has a visible range. So how about Sunlight? Does it light more on Mercury and less on Pluto? And what about planets that are not in the Solar System?
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How does “planetary protection” apply to Europa since Europa is not a planet?

NASA has this "planetary protection" scheme. But it seems to apply to non-planets, like Enceladus and Europa. Thus Galileo and Cassini probes are crashed into their gas giants. How does this add up? ...
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When will we be able to conclusively confirm or disprove Bode's law?

I am reading Heinlein's Time for the Stars(1956) and some of the characters are very excited about confirming Bode's law. The formula suggests that, extending outward, each planet would be ...
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Why is TRAPPIST-1f considered habitable?

The TRAPPIST-1f is in the TRAPPIST-1 system discovered recently with seven planets. Three of them are said to be in the habitable zone. But the data says that the average temperature on the TRAPPIST-...
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Exoplanet(s) that share orbit?

Has Kepler (or any other survey) found an exoplanet with a similar orbit as another exoplanet around the same star? The current IAU definition of a planet requires that "a planet has cleared its ...
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Is there a calculation for determining the thickness of a planet's atmosphere?

I'm wondering if there a way to determine how thick (from the surface to the edge of space(karman line)) a planet's atmosphere would be. Assume an earth body like Earth or Mars (not a gas giant). I ...
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Rocky Planet around Proxima Centauri - how can we learn more about it?

Besides an epic millennium-long interstellar voyage by a probe, what can we possibly do to learn more about this rocky planet discovered around Proxima Centauri? I understand that we have some ...
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Which of the outer planets could you see with the naked eye if you were in close proximity?

My question is which of the outer planets you could see with the naked eye if you were in close proximity to them. It's pretty obvious the human eye can see the inner planets through to Mars, but I ...
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What do the enclosed numbers represent? [closed]

A friend asked me what the numbers in the following image represent: ...
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Which planets and moons can you walk on?

Which planets and moons have a surface where you could survive with a conventional or near-future spacesuit? Assume oxygen, water, and food supplies are accounted for, but roughly current limitations ...
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Why would Hollywood's Planet X (at earth's L3) be unstable?

This NASA website states "NASA is unlikely to find any use for the L3 point since it remains hidden behind the Sun at all times. The idea of a hidden "Planet-X" at the L3 point has been a popular ...
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Has any other term been used for a solar day on a solar system body besides “sol” on Mars?

My interest was piqued by this question and answer. For several reasons NASA needed to refer frequently and extensively to a Martian solar day, and "sol" became the nom du jour. There have been ...
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Are any spacecraft heading remotely where Planet 9 is expected to be?

Planet 9, the hypothetical planet predicted Batygin and Brown, is expected to have an apoasis near the galactic center. Is there a spacecraft that is heading in that direction? Specifically, they ...
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What is the exact format of the JPL ephemeris files?

I'm attempting to do some basic planet position calculations using the JPL ephemeris data. The first step is to properly parse the files. Here's my understanding so far: The header file gives a ...
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Could two planet-like objects be created-as or form a binary pair that orbits something else?

Could two identical or slightly different planets (or planet-like objects if you want to be pedantic) form a binary pair that then orbit some other larger gravitic object (like a star)? I was ...
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Could twin planets exist and share the same orbit?

Could there be a stable orbit shared by two planets with the same mass and density? Regardless of whether the formation of such system is possible or not. For example, if Earth and Venus could have ...
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Which of the planets could we detect today from just the movements of the sun?

Assume that despite our current level of space exploration and technology, we have somehow missed the existence of the other planets in our solar system. We have developed various methods of ...
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Is there a term to refer to a planet and its accompanying moons as a whole collection?

I am trying to find out of there is a term that can be used when referring to both a planet and any accompanying moons (if present) as a whole collection. For example if you were to refer to Mars and ...
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From which celestial bodies do we have samples?

Excluding our own, which bodies have we directly (or indirectly) gathered samples from? I'm aware of these: Moon: moon rocks from Apollo Mars: Martian meteorites found on Earth What else?
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Planet building: collision without fragmentation?

Our Solar system poses a significant problem for colonisation insofar that the rocky planets are predominantly on the... small scale; at least as far as mass is concerned (Earth is the exception ...
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How do we determine and estimate the age of exoplanets like Kepler-452b?

Scientists recently discovered an exoplanet named Kepler-452b which they state is "is 6 billion years old". How did they determine this age? How could we possibly predict the age of any exoplanet? ...
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What is the relationship between New Horizons launch and Pluto's loss of Planet status?

According to NASA "New Horizons launched on Jan. 19, 2006" according to Wikipedia this is about the same time Pluto started on the path to loss of planet status. Is it just coincidence that both of ...
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How much do we know about minerals and raw materials that are in our solar system?

Based on satellite and robots research, is there an overview/inventory of mineral resources that has been discovered till now on the planets, moons, asteroids and comets of our solar system (e.g. list,...
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What is the difference between mean anomaly and mean longitude?

I am an engineer who is in charge of writing some software which makes use of those two elements. But I am a bit confused, both seem to be almost the same although there is a small difference, which ...
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Does Saturn have a solid surface?

This page argues that Saturn's density tells scientists that it has a liquid metal core with maybe some rocky chunks: The core region of Saturn may never be directly observed. Neither has the ...
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Planetary migration due to tidal forces

The fine U. Washington article Some potentially habitable planets began as gaseous, Neptune-like worlds mentions twice that tidal forces can induce inward planet migration. Two phenomena known to ...
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How do apsides of celestial bodies get their names?

If you look at this site, it shows some of our common bodies' apsidal names, as shown below: Objects Periapsis Apoapsis Galaxy Perigalacticon Apogalacticon Black hole Perimélasma ...
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What happens if we bury a human on other planets or moons [closed]

Given that there are no organisms on other planets/moons, if we bury a dead human (or other organisms), will it decay? I think the body will be intact as on earth there are several organisms/micro ...
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Adapting to Increased Gravity on Alien Planets

What would mankind use in order to adapt or merely cope with the effects of a large increase of gravity on an alien world? Assuming there are no other problems we would face.
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Is it a pure coincindence that the magnetic poles of Earth are near the geographic poles?

On Earth the magnetic poles are near the geographic poles. Does Earth have this situation by pure luck? What is the situation on other planets?
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Have we found another earthlike planet?

Space Colonization has become a popular trend in Sci-Fi movies. It would be a thrilling experience if we could travel from planet to planet. Have we found another earth-like planet close enough for ...
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How do we measure the atmospheres of Solar system planets?

How much is it possible to measure from Earth and how accurately without sending probes to the planets? I am curious about how atmospheric boundary (altitude), atmospheric pressure, scale height were ...
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Are multiple sub-probes feasible for fast flyby missions to outer Solar System objects?

The obvious drawback with a flyby mission compared with an orbiter is of course that an orbiter could make several flyby's. I wonder if the following ideas about mission design could help make flyby ...
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NASA just announced 715 new exoplanets were discovered, what do we know about them?

I have been trying to find information on how far away these new exoplanets are from Sol. Does anybody have a map or a table that shows their distance to us in light years. There only seem to be 100 ...
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What is the most distant planet from the Earth that a spacecraft has visited to date?

What is the most distant planet from the earth that a spacecraft visited has visited so far? What was the mission and when did it happen?
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If there are Earth size bodies drifting in space could we identify them?

I don't think there is any reasonable doubt that comets have been ejected from ours and other solar systems and are drifting in the vast voids of space. If there where larger bodies say the size of ...
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Can a “free launch” from a space elevator really be free?

The question Benefit of sling shot effect with a space elevator implies that you can get free $\Delta V$ from a space elevator launch. As highlighted in this answer on SciFi quoting Sheffield book "...
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What properties are used to quantify the odds of a star harboring earth-like life?

Say you start with a list of stars. What properties do we believe to be critical in the present existence or future formation of earth-like life in those star systems? How can one reasonably pare down ...
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Changing the rotational rate of a natural body

Let's say that for the purpose of terraforming, we need to speed up the rotation of a planet (like Venus), a moon or an asteroid to near Earthian day. How would we go about doing this? Can this be ...
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What places in the Solar System have temperatures suitable to humans?

They say, Mercury polar areas have temperatures of around 0C. What other areas in the Solar System (on the planets or on the moons, on the surface or under) in what seasons have temperatures ...
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Flying on dense atmosphere planets & moons

Would certain types of flying be possible on planets like Venus, Titan (which is a moon, I know :P), or gas-giants? I'm thinking on the aspects of these types of aircrafts: airships (that uses only ...