(136108) Haumea (North Up, East Left)
136108 Haumea, is a dwarf planet located beyond Neptune's orbit. It was discovered in 2004 by a team headed by Mike Brown of Caltech at the Palomar Observatory in the United States and independently in 2005, by a team headed by José Luis Ortiz Moreno at the Sierra Nevada Observatory in Spain, though the latter claim has been contested. On September 17, 2008, it was recognized as a dwarf planet by the International Astronomical Union (IAU) and named after Haumea, the Hawaiian goddess of childbirth. Its mass is about one-third that of Pluto, and 1/1400 that of Earth. Although its shape has not been directly observed, calculations from its light curve indicate that it is a triaxial ellipsoid, with its major axis twice as long as its minor. Its gravity is thought to be sufficient for it to have relaxed into hydrostatic equilibrium, making it a dwarf planet. Haumea's elongated shape together with its rapid rotation, high density, and high albedo (from a surface of crystalline water ice), are thought to be the consequences of a giant collision, which left Haumea the largest member of a collisional family that includes several large trans-Neptunian objects (TNOs) and Haumea's two known moons, Hi’iaka and Namaka. Haumea has an orbital period of 284 Earth years, a perihelion of 35 AU, and an orbital inclination of 28°. It passed aphelion in early 1992 and at the date of this image was 50.6 AU from the Sun. Haumea's orbit has a slightly greater eccentricity than that of the other members of its collisional family. This is thought to be due to Haumea's weak 7:12 orbital resonance with Neptune gradually modifying its initial orbit over the course of a billion years, through the Kozai effect, which allows the exchange of an orbit's inclination for increased eccentricity. With a visual magnitude of 17.3, Haumea is the third-brightest object in the Kuiper belt after Pluto and Makemake, and easily observable with a large amateur telescope. However, because the planets and most small Solar System bodies share a common orbital alignment from their formation in the primordial disk of the Solar System, most early surveys for distant objects focused on the projection on the sky of this common plane, called the ecliptic. As the region of sky close to the ecliptic became well explored, later sky surveys began looking for objects that had been dynamically excited into orbits with higher inclinations, as well as more distant objects, with slower mean motions across the sky. These surveys eventually covered the location of Haumea, with its high orbital inclination and current position far from the ecliptic. Haumea displays large fluctuations in brightness over a period of 3.9 hours, which can only be explained by a rotational period of this length. This is faster than any other known equilibrium body in the Solar System, and indeed faster than any other known body larger than 100 km in diameter. This rapid rotation is thought to have been caused by the impact that created its satellites and collisional family. This image comprises 5 x Luminance (180 seconds each) , 0.5m f/2.9 ASA Astrograph with FLI ML3200 camera at an altitude of 75 degrees on 21 April 2017, 8 days after opposition at magnitude 17.3.  The bright star to the south-east is magnitude 8.5 SAO 100875 in Bootes. The field of view is 18’ x 18’.
Hills Observatory: 1 January 2013 to 6 May 2018