Haumea: The Oval-Shaped Dwarf Planet

Haumea is a dwarf planet located in the Kuiper Belt, beyond the orbit of Neptune. It is one of the fastest rotating large objects in our solar system, completing a rotation every 3.9 hours.

This rapid rotation gives Haumea its distinctive elongated, oval shape rather than the spherical form typical of most planets and dwarf planets. Scientists classify it as a Jacobi ellipsoid, stretched along its longest axis.

Haumea is named after the Hawaiian goddess of fertility and childbirth. Its two known moons, Hiʻiaka and Namaka, are named after Haumea's daughters in Hawaiian mythology.

Haumea was discovered in 2004 by two independent teams. Mike Brown's team at Caltech discovered it on December 28, 2004, from images taken on May 6, 2004, at Palomar Observatory.

Meanwhile, José Luis Ortiz Moreno's team at the Sierra Nevada Observatory in Spain discovered it from images taken on March 7-10, 2003, and announced their discovery on July 27, 2005.

This led to a controversy over who should receive credit for the discovery. The International Astronomical Union ultimately decided to accept Brown's proposed name, Haumea, in September 2008.

Haumea's most distinctive feature is its elongated, oval shape, which is the result of its extremely rapid rotation. With a rotation period of just 3.9 hours, Haumea spins faster than any other known large body in the solar system.

This rapid rotation causes Haumea to stretch into an ellipsoid shape rather than maintaining a spherical form. Scientists calculate that Haumea's dimensions are approximately 2,322 × 1,704 × 1,138 km, making it about as long in one direction as Pluto is wide.

Haumea is what astronomers call a "Jacobian ellipsoid" - a shape that rotating fluid bodies naturally assume under their own gravity. Despite its unusual shape, Haumea is in hydrostatic equilibrium, one of the requirements for dwarf planet status.

Haumea orbits the Sun at an average distance of 43.1 AU, taking 285 Earth years to complete one orbit. Its orbit is moderately eccentric and inclined relative to the plane of the solar system.

Haumea has two known moons: Hiʻiaka and Namaka. Hiʻiaka is the larger outer moon, with a diameter of about 310 km, while Namaka is the smaller inner moon, about 170 km in diameter.

Spectroscopic observations have revealed that Haumea's surface is composed almost entirely of crystalline water ice. This is unusual for Kuiper Belt objects, as amorphous ice is more common in the cold outer solar system.

Haumea is the largest member of a collisional family of objects in the Kuiper Belt. This family consists of Haumea, its moons, and several other Kuiper Belt objects that share similar orbital characteristics and surface properties.

Scientists believe that this family formed billions of years ago when a large impact struck a proto-Haumea, ejecting fragments into space. These fragments now orbit the Sun with similar orbits to Haumea.

The Haumea family members share distinctive spectral features, particularly strong water ice absorption bands, suggesting they all originated from the same parent body. This makes the Haumea family unique in the Kuiper Belt.