Questions tagged [dwarf-planets]

Questions regarding celestial bodies that are in hydrostatic equilibrium (spheroidal) and orbit the Sun directly, but do not fulfill the IAU's criterion of "clearing" their neighbourhood of planetesimals.

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Why do most dwarf planets have mass comparable to moon?

It was quite interesting to spot that most dwarf planets have masses close to that of our moon (if we let an error to fluctuate within two orders of magnitude). Why it is so? Is there any common ...
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15 votes
3 answers
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Undiscovered dwarf planets

Scientists think there may be dozens of undiscovered dwarf planets in the Solar system. What I find intriguing is that, we have been able to detect distant galaxies and clusters, locate supermassive ...
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1 answer
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Did we find any exo–dwarf-planet?

We have discovered thousands of exoplanets so far. Do we categorize them into planets and dwarf planets, too?
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2 votes
0 answers
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Based on discoveries of new TNOs since 2016, is planet Nine still necessary to explain the TNO's orbits?

It is almost five years since the announcement of the likelyhood of another planet that is responsible for clustering eTNO's orbits, very close perihelia of detached dwarf planets to the Sun, and high ...
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1 answer
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Is there still a possibility that Makemake is not ellipsoidal but asteroid-shaped?

In 2008, Makemake and Haumea have been named under the expectation that they would prove to be dwarf planets. Well, did they prove to be ones? Haumea obviously did since we know its shape which is a ...
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2 votes
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Can telescopes determine whether Hygiea is in hydrostatic equilibrium?

10 Hygiea is a spherical body in the main asteroid belt. With future telescopes like the Vera Rubin LSST or the James Webb Space Telescope, can we determine whether Hygiea is actually in hydrostatic ...
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9 votes
1 answer
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Why doesn't the IAU consider Quaoar to be a dwarf planet?

Only Ceres, Pluto, Haumea, Makemake and Eris are listed by the IAU as dwarf planets. Quaoar is bigger than Ceres, yet it doesn't make the cut. In fact, it fits the IAU description of a dwarf planet ...
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2 votes
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Looking for a Solar System Simulator including the smaller celestial body, for macOS

I am researching for a sci-fi novel that will happen in 2136. For this I would like to know specific positions of "smaller" celestial bodies in our Solar System. An example can be the dwarf planet ...
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Up to 384 minor planets (including Pluto) qualify as planets?

In 2006, the International Astronomical Union redefined the definition of planet in order to exclude Pluto, Eris, and several other objects whose category was disputed. This new definition of a planet ...
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2 votes
6 answers
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Would planet explode without gravity?

A planet (as well as a dwarf planet) must, according to the IAU definition, have sufficient mass to assume hydrostatic equilibrium (a nearly round shape). Does it mean they would break apart or ...
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4 votes
1 answer
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Could Planet Nine be much smaller than thought previously?

In 2016, Caltech astronomers began testing a Planet Nine hypothesis to explain the eccentric and inclined orbits of distant dwarf planets such as Sedna, 2015 TG387, Niku, and 2012 VP113. The ...
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Why was Dawn's (the spacecraft) flight path circular? [closed]

In comparison to the twin Voyagers, Dawn's flight path circled the sun in an anti-clockwise manner. The map of its path shows its targets, Ceres and Vesta were in a trajectory that was close to a ...
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5 votes
0 answers
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Are occultation observations used/useful for orbit determination?

The IAU Minor Planet Center lists $(486958)\space 2014 \space MU_{69}$ "Ultima Thule" as having an uncertainty parameter of 2, based on the observation arc of 851 days, from its discovery in 2014, to ...
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3 votes
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Trans-Neptunian Dwarf Planet near Heliopause

Is there any reason to think a Trans-Neptunian dwarf planet, the size of Pluto, could not exist in a Keplerian orbit 120AU from the Sun? If such an object existed, and came within 0.1AU of the ...
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2 votes
2 answers
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Is there a reason why the IAU differenciates objects in the SS orbiting the sun into a particular classification but it doesnt for satellites?

The IAU has different classifications for objects in the solar system orbiting the sun, they can be according to their shape and if they clear their neighborhood of other material around its orbits , ...
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1 answer
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What would the sun look like from aphelion of The Goblin's orbit?

I was amazed to find out about the discovery of The Goblin 2015 TG387 with an orbital period of more than 32 thousand years and a aphelion of more than 1955 AU! That is an astonishing distance. What ...
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1 answer
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How did Biden become VP? (naming of 2012 VP113)

The Carnegie Science article Solar System's Edge Redefined describes the discovery of the object 2012 VP113. Wikipedia's article 2012 VP113 says: Nickname: 2012 VP113 was abbreviated "VP" ...
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How do they know how far out Farout is? (2018 VG18)

The Carnegie Science article Discovered: The Most-Distant Solar System Object Ever Observed begins: Washington, DC— A team of astronomers has discovered the most-distant body ever observed in our ...
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What is the percent flattening in Haumea?

I've recently noticed that in Wikipedia articles such as Pluto (Link), there's this number that says how much flattened it is (Definition Here). In Pluto, it's >1%. Haumea, which is a very flattened ...
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What does it mean for a planet to be just 300 kms across?

The recently discovered Planet Goblin is just 300 kms across. While I perfectly understand what it literally means, I'm having trouble wrapping this in my head. Does it mean I can imagine the planet ...
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4 votes
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What would be the sizes of the bodies created from Jupiter's trojans?

If all trojans from the Greek camp and all the trojans of the Trojan camp were combined into two bodies respectively, what sizes and masses these bodies would have? Would they qualify as dwarf planets?...
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2 votes
1 answer
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Assuming 2007 OR10 is in tidal lock with its satellite, what is its mass?

Its rotation period is 45 hours. Its satellite is at the distance of 15000 km. Given this data, and assuming the satellite's orbital period the same as the main body's rotation period, 45 hours, what ...
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9 votes
3 answers
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Is Jupiter a dwarf planet?

I know the question seems silly, but as far as I've understood, is this the definition of a dwarf planet: circling around a star, and not being a star itself having a round shape (otherwise every ...
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12 votes
1 answer
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How does 2015 RR245 compare to the other KBOs predicting "Planet 9"?

2015 RR245 was recently announced, in a highly eccentric orbit in the KBO. From what I understand, the so called "Planet 9" was predicted because these objects tended to be pointed in a particular ...
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3 votes
2 answers
446 views

Why 225088 Gonggong is not a dwarf Planet yet?

Per definition a dwarf planet is: a celestial body that (a) is in orbit around the Sun, (b) has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic ...
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3 answers
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Brown Dwarf transcending past the sun with the naked eye [closed]

I seen with my naked eye in mid 2014 from Ca. right after sunrise a black spot in front of the Sun.I observed it for about a hour with my naked eye. Here is a picture that closely resembles what I ...
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4 votes
1 answer
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Is Ceres a terrestrial-type (dwarf) planet?

Does Ceres belong to the terrestrial-type celestial bodies?
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3 votes
1 answer
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IAU Dwarf planet definition Point 2.b - is not a satellite

I am a bit confused with point 2.d of the IAU's resolution on dwarf planets. (2) A "dwarf planet" is a celestial body that (a) is in orbit around the Sun (b) has sufficient mass for its ...
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10 votes
1 answer
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Pluto- Current theories regarding its geological nature?

The images of New Horizons from Pluto will take more a year to arrive from space, for the moment with have some compressed images as a preview. Nasa has advanced some information regarding the ...
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2 votes
1 answer
356 views

Is the Dwarf Planet class really necessary?

Another way of asking this is, what is the difference between dwarf planets and asteroids? Aren't they the same things? It's just that some asteroids are spherical and others aren't...or is there ...
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12 votes
2 answers
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Can there be an object with planetary discriminant between Ceres and Neptune?

The planetary discriminant is a measure of how dominant a body is within its region of the solar system. For (true) planets, it is $>10000$ and for dwarf planets it is $<1$. (See this answer to "...
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4 votes
1 answer
417 views

How long does it take Dawn to orbit Ceres?

I haven't been able to find the orbit time of Dawn around Ceres. Do you know how long it takes?
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8 votes
2 answers
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Likelihood of a stable system with a dwarf planet's orbit inside that of a gas giant

I keep thinking of various planetary system configurations, and would like to know: What are the fundamental references based on Monte Carlo long-term simulation of planetary systems' evolution that ...
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15 votes
3 answers
790 views

Planets and Pluto? Neptune?

If one of the rules to be a planet is that it needs to clear ALL objects from their orbit, does this also make Neptune a non-planet? Since it has thus far failed to clear Pluto (and based on an answer ...
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12 votes
2 answers
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How can astronomers determine the difference between "hydrostatic equilibrium" and "just happens to be spherical"?

This is relevant for the definition of a dwarf planet. I presume the answer will be, well, if we can tell the mass of the body and guess the material. I don't find this very satisfactory because (1)...
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2 votes
1 answer
198 views

What is the danger for Ceres of collision with other asteroids?

In the context of possible colonization of Ceres, would not such colony be totally impossible because of high probability of collision of Ceres with other asteroids in the Asteroid Belt?
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1 vote
1 answer
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When the set of official dwarf planets is expected to increase?

When the set of official dwarf planets is expected to increase or new bodies considered for inclusion?
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15 votes
6 answers
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Is Pluto still a dwarf planet?

Recent news seem to suggest that astronomers are arguing about whether Pluto should become a planet again. However, I cannot find an official source for this. Is this actually true?
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18 votes
1 answer
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How did scientists determine an estimate of the number of planets greater than Sedna's size to exist in the Inner Oort Cloud?

In the article, New Dwarf Planet Found at Solar System's Edge, Hints at Possible Faraway 'Planet X' (Wall, 2014) where they report on research and observations performed by astronomers that discovered ...
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59 votes
7 answers
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How many planets are there in this solar system?

So, in school (that's a long time ago) they have been teaching us there are 9 planets in our solar system. Mercury Venus Earth Mars Jupiter Saturn Uranus Neptune Pluto But every now and then I keep ...
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19 votes
2 answers
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What physical features determine if a planet is a major, minor or dwarf planet?

Like many, when I was growing up, we always were taught, hence always learned that there were 9 planets. However, recently, decisions were made and all of a sudden there were 8 major planets and a ...
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