Mass and shape
Haumea is the third closest dwarf planet to the Sun and is located beyond the orbit of Neptune. It is orbited by two moons, Hiʻiaka and Namaka, which are thought to have originated from an impact with a large object. By observing the orbits of these moons and applying Kepler's third law the mass of the whole system can be calculated. This estimated mass, which is almost exclusively concentrated in Haumea itself, amounts to 4.2×10²¹ kg - or roughly one third of Pluto's mass.[1] Haumea is close and big enough to allow for the measurement of its thermal emission spectrum, which in turn can be used to deduce its albedo. Knowing the albedo of an object, its size can be deduced from its brightness. This calculation is more complicated in Haumea's case because it is deformed into the shape of a triaxial ellipsoid due to its high rotation speed. The axes of this ellipsoid are estimated to be 1.960 km, 1.518 km and 996 km in length. Haumea has a thin ring system, which was discovered in 2017 after scientists watched Haumea passed infront of a star.
Discovery
Haumea was discovered in December of 2004 by a team from Caltech at the Palomar Observatory in the United States in a project headed by Mike Brown from images taken on May 6th, 2004 from the W.M. Keck Observatory. They published an online abstract about their discovery on July 20th, 2005, and announced their discovery at a conference in September of that year.[2] Meanwhile, José Luis Ortiz Moreno and his team from the Instituto de Astrofísica de Andalucía at Sierra Nevada Observatory in Spain emailed the IAU Minor Planet Center of the discovery of Haumea on July 27th, 2005, claiming they had found it on images taken from March 7th to 10th, 2003. The IAU announcement on September 17, 2008, that Haumea had been accepted as a dwarf planet, did not mention a discoverer. The location of discovery was listed as the Sierra Nevada Observatory of the Spanish team, but the chosen name, Haumea, was the Caltech proposal.[3][4] Haumea is the Hawaiian goddess of fertility and childbirth and also the mother of the deities Hi'iaka and Namaka - who are the eponyms of Haumea's satellites.[5]
Images
