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A constellation is a
group of stars that form
a pattern or shape
in the night sky.
There are a total of 88
modern constellations,
including Orion, Taurus,
Pegasus and Ursa Major.
Orion
Haumea (pronounced how-may-a) is a rugby-shaped dwarf planet that was discovered in December 2004.
It orbits the Sun at an average distance of 43.1 astronomical units (AU), but can reach as close as 34.7 AU and as far out as 51.5 AU. This gives Haumea an orbital period of around 283 years.
It's around one-third the mass of Pluto, however, because of its low density, it is actually wider. Observations of the way it reflects sunlight suggest that it's shaped like a rugby ball. In other words, one of its axes is twice as long as the other. The odd shape is caused by its very fast rotation rate - it spins once every 4 hours.
Haumea has two known moons, named HiĘ»iaka and Namaka, and the surface temperature on all three is thought to be around -240°C (or 32K).
Haumea is also a type of plutoid - a dwarf planet that circles the Sun beyond the orbit of Neptune.
| Facts and Figures | Ceres | Pluto | Haumea | Makemake | Eris |
| Orbital distance (AU)1 | 2.77 | 39.5 | 43.1 | 45.8 | 67.7 |
| Orbital Inclination | 10.6° | 17.1° | 28.2° | 29° | 44° |
| Radius (KM) | 487 | 1,137 | 1,436 | 750 | 1,300 |
| Mass (Earth Masses)2 | 0.00016 | 0.00213 | 0.0007 | 0.0007 | 0.003 |
| Year Length (Earth Years) | 4.6 | 248.5 | 283.3 | 309.9 | 557 |
| Day Length (Earth Days) | 0.38 | 6.39 | 0.16 | Unknown | Unknown |
| Surface Gravity (g)3 | 0.003 | 0.04 | 0.044 | 0.05 | 0.08 |
| Surface Temperature | about -105°C | about -230°C | about -240°C | about -243°C | about -240°C |
| Number of moons | 0 | 3 | 2 | 0 | 1 |
