Dwarf Planets
| Key | |||||
|---|---|---|---|---|---|
| † Ceres |
‡ plutoid |
||||
Dwarf planets are large enough to have achieved hydrostatic equilibrium, but have not cleared their neighbourhoods of similar objects. There are currently five dwarf planets recognized by the IAU in this category. Ceres orbits in the asteroid belt, between the orbits of Mars and Jupiter. The others orbit beyond Neptune and are sub-classified as plutoids.
| †Ceres | ‡Pluto | ‡Haumea | ‡Makemake | ‡Eris | ||
|---|---|---|---|---|---|---|
| Astronomical symbol | ||||||
| Minor planet number | 1 | 134340 | 136108 | 136472 | 136199 | |
| Mean distance from Sun |
km AU |
413,700,000 2.766 |
5,906,380,000 39.482 |
6,484,000,000 43.335 |
6,850,000,000 45.792 |
10,210,000,000 67.668 |
| Mean radius | km :E |
471 0.0738 |
1,148.07 0.180 |
575 0.1537 |
750+200 −100 0.12 |
1,200 0.19 |
| Volume | km3 :E |
4.37×108 0.0005 |
6.33×109 0.007 |
1.3–1.6×109 0.001 |
1.8×109 0.002 |
7.23×109 0.008 |
| Surface area | km² :E |
2,800,000 0.0055 |
17,000,000 0.0333 |
6,800,000 0.0133 |
7,000,000 0.015 |
18,000,000 0.0353 |
| Mass | kg :E |
9.5×1020 0.00016 |
1.3×1022 0.0022 |
4.01 ± 0.04×1021 0.0007 |
3×1021 0.0005 |
1.7×1022 0.0028 |
| Density | g/cm3 | 2.08 | 2.0 | 2.6–3.3 | 2.0 | 2.25 |
| Equatorial gravity | m/s2 | 0.27 | 0.60 | 0.44 | 0.5 | ~0.8 |
| Escape velocity | km/s | 0.51 | 1.23 | 0.84 | 0.8 | 1.37 |
| Rotation period | days | 0.3781 | −6.38718 | 0.167 | ? | ? |
| Orbital period | years | 4.599 | 247.92065 | 285.4 | 309.9 | 557 |
| Mean orbital speed | km/s | 17.882 | 4.7490 | 4.484 | 4.4 | 3.436 |
| Eccentricity | 0.080 | 0.24880766 | 0.18874 | 0.159 | 0.44177 | |
| Inclination | deg. | 10.587 | 17.14175 | 28.19 | 28.96 | 44.187 |
| Axial tilt | deg. | 4 | 119.61 | ? | ? | ? |
| Mean surface temperature | K | 167 | 40 | <50 | 30 | 30 |
| Atmospheric composition | H2O, O2 | N2, CH4 | N2, CH4. | N2, CH4 | ||
| Number of known moons | 0 | 5 | 2 | 0 | 1 | |
| Planetary discriminant | 0.33 | 0.077 | 0.023 | 0.02 | 0.10 | |
Read more about this topic: List Of Gravitationally Rounded Objects Of The Solar System
Famous quotes containing the words dwarf and/or planets:
“A dwarf who brings a standard along with him to measure his own size—take my word, is a dwarf in more articles than one.”
—Laurence Sterne (1713–1768)
“Perhaps when distant people on other planets pick up some wave-length of ours all they hear is a continuous scream.”
—Iris Murdoch (b. 1919)