65803 Didymos

65803 Didymos is a sub-kilometer, binary Near-Earth Object of the Apollo group. The asteroid has a small 160-meter natural satellite known as Dimorphos.
== Discovery ==
65803 Didymos was discovered in 1996 by the University of Arizona and the Lunar and Planetary Laboratory's Spacewatch survey telescope at Kitt Peak National Observatory in Arizona.
== Orbit ==
Didymos orbits the Sun at a mean distance of 1.0 - 2.3 AU once every 770 days (approx. 2 years). Disymos's orbit has an eccentricity of 0.38 and an inclination of 3 degrees with respect to the ecliptic. In November 2003, Didymos passed 7.18 million km by Earth and will not come again until November 2123, with a distance of 5.86 million km. Didymos also occasionally passes by Mars.
== Physical Characteristics ==
In the SMASS classification system, Didymos is classified as an Xk-Type asteroid, a blend between an X-Type and a rare K-Type asteroid. Visible and near-infrared spectroscopy showed that it is mostly silicate, which would make it a stony S-Type asteroid. 
It rotates rather quickly, with a period of 2.26 hours and it has a low brightness variation of 0.08 magnitude.
=== Satellite ===
Main article: Dimorphos
Because Didymos is a binary asteroid, it has a small 160-meter natural satellite, called Dimorphos. Dimorphos has a circular, retrograde orbit with an orbital period of ~12 hours. Dimorphos was previously known as S/2003 (65803) 1 or "Didymoon"
== Naming ==
The near Earth object was named "Didymos", Greek for "twin", due to its binary nature.
Its satellite later was given the name "Dimorphos", Greek for "having two forms"
== Exploration ==
In September 2022, the DART (Double Asteroid Redirection Test) Spacecraft crashed into Dimorphos to prove the effectiveness of deflecting an asteroid to prevent it from colliding with Earth. (This test was successful.) The DART Spacecraft also deployed the LICIACube, a small flyby cubesat to observe the effects of the collision for another 15 days after the test.
The European Space Agency plans to launch another spacecraft known as Hera to survey the dynamical effects of the DART impact and to measure the crater left on Dimorphos by DART.
Category:Potentially Hazardous
Category:Apollo
Category:Near Earth Object
Category:Rubble Pile Asteroid
Category:Binary Asteroid
Category:S type
Category:Other Spectral Types
Category:Mars-Crosser
Category:Objects Not in Hydrostatic Equilibrium
Category:Objects with No Atmosphere
Category:Objects with Natural Satellites
Category:Inner Solar System Object
Category:Asteroids
Category:Named Objects
Category:Named Minor Planets
Category:Numbered Objects
Category:Numbered Minor Planets
Category:Objects Visited by Spacecraft
Category:Binary Object