Hydra (moon)

Pluto system 2005 discovery images

Pluto and its satellites (2005)

Hydra is a natural satellite of Pluto, discovered in June 2005 by the Hubble Space Telescope's Pluto Companion Search Team, which consists of Hal A. Weaver, Alan Stern, Max J. Mutchler, Andrew J. Steffl, Marc W. Buie, William J. Merline, John R. Spencer, Eliot F. Young, and Leslie A. Young. Hydra is the outermost known moon of Pluto and was named after the Hydra, the nine-headed serpent from Greek mythology. Along with Charon, Nix, Kerberos, and Styx, Hydra is part of a complex system of satellites orbiting the dwarf planet Pluto.

Discovery and Naming

Hydra was discovered along with Nix in June 2005, while astronomers were using the Hubble Space Telescope to search for rings around Pluto. Its discovery was announced by the International Astronomical Union (IAU) on July 20, 2005. Hydra, along with Nix, was initially given the provisional designation S/2005 P 1. The moon was later named Hydra on June 21, 2006, after the mythical Hydra which was a multi-headed serpent that was defeated by Hercules as one of his twelve labors. The name reflects the moon's position as the second known satellite of Pluto at the time of discovery, with the nine heads of the Hydra symbolizing the moon's discovery as part of Pluto's increasingly complex system.

Physical Characteristics

Hydra is irregularly shaped and has a dimension of approximately 50 km × 40 km × 30 km, making it the second-largest moon of Pluto, after Charon. Its surface is thought to be composed primarily of water ice. Observations from the New Horizons mission in 2015 provided more detailed images of Hydra, revealing its irregular shape and hinting at its geological history. The moon's surface is highly reflective, suggesting a relatively young and possibly resurfaced terrain covered by water ice.

Orbit

Hydra orbits Pluto at a distance of approximately 64,800 kilometers (40,200 miles), completing an orbit around Pluto roughly every 38 days. Its orbit is slightly inclined and eccentric, typical of moons in a complex satellite system. Hydra, along with the other moons of Pluto, is locked in a 3:2 mean-motion resonance with Charon, the largest of Pluto's moons, which contributes to the stability of the satellite system.

Exploration

The most significant exploration of Hydra came from the New Horizons spacecraft, which flew by the Pluto system in July 2015. New Horizons provided the first close-up images of Hydra, revealing its shape, size, and surface characteristics in greater detail than ever before. These observations have helped scientists to understand more about Hydra's composition, its formation, and its history within the Pluto system.

Significance

Hydra's discovery and subsequent observations have significantly contributed to our understanding of the Pluto system. It has shown that dwarf planets can have complex satellite systems, similar to those of larger planets. The study of Hydra and Pluto's other moons also provides insights into the Kuiper Belt, a region of the Solar System beyond Neptune that is populated with small, icy bodies, including dwarf planets and comets.