3581 Alvarez

3581 Alvarez is a stony Amor asteroid and near-Earth object of approximately 1.8 kilometers in diameter. It was discovered in 1985 by American astronomers Carolyn S. Shoemaker and Eugene Merle Shoemaker at the Palomar Observatory in California. The asteroid is notable for its highly eccentric orbit, which brings it within the orbit of Mars and relatively close to Earth, classifying it as a potentially hazardous asteroid.

Discovery and naming

The asteroid was discovered on 23 April 1985, by the renowned astronomer team of Carolyn S. Shoemaker and Eugene Merle Shoemaker during the Palomar Asteroid and Comet Survey at Palomar Observatory. It was given the provisional designation 1985 HC before receiving its permanent number. The name "Alvarez" honors the physicist Luis Walter Alvarez and his son, the geologist Walter Alvarez, both of University of California, Berkeley. Their collaborative work on the Alvarez hypothesis, which proposed that the Cretaceous–Paleogene extinction event was caused by an asteroid impact, provided a seminal link between planetary science and paleontology. The naming citation was published by the Minor Planet Center on 2 April 1988.

Orbit and classification

3581 Alvarez is classified as an Amor asteroid, a group of near-Earth objects whose orbits lie outside of Earth's but approach it, and it is also a Mars-crossing asteroid. It orbits the Sun at a distance of 1.1–2.5 AU once every 2 years and 5 months (891 days), with a high orbital eccentricity of 0.40 and an inclination of 28° with respect to the ecliptic. Its orbit is dynamically unstable over long timescales due to gravitational perturbations from the terrestrial planets, particularly Mars and Earth. Observations by the NEOWISE mission of NASA and radar studies from facilities like the Arecibo Observatory have helped refine its orbital parameters, confirming its status as a potentially hazardous asteroid given its size and minimum orbit intersection distance with Earth.

Physical characteristics

Alvarez is characterized as a bright, stony S-type asteroid in the Tholen classification system, consistent with its high albedo. Photometric observations have determined a rotation period of approximately 4.0 hours, a relatively fast spin rate for an object of its size. Measurements from the Infrared Astronomical Satellite (IRAS) and subsequent surveys estimate its mean diameter to be about 1.8 kilometers. Its surface composition is likely similar to that of ordinary chondrite meteorites. Studies of its lightcurve and spectral properties contribute to the broader understanding of the physical characteristics of near-Earth objects and their potential relationship to meteorites found on Earth.

See also

* List of named minor planets (alphabetical) * List of minor planets: 3001–4000 * Alvarez hypothesis * Shoemaker–Levy 9

Category:Amor asteroids Category:Discoveries by Carolyn S. Shoemaker Category:Discoveries by Eugene Merle Shoemaker Category:Potentially hazardous asteroids Category:Named minor planets