(433) Eros
(433) Eros is an asteroid that forms part of the Amor asteroids and was discovered by Carl Gustav Witt (1866-1946) in 1898. It has a perihelion of 1.1 AU, a distance that periodically brings it closer to Earth, and is therefore a near-Earth asteroid (NEA). From a chemical point of view, it is classified as an S-type asteroid, formed by asteroids composed of silicates.
It has an irregular shape, with dimensions of 34.4×11.2×11.2 km, and a central narrowing that, when viewed from the poles, gives it the shape of a banana or a peanut. Its mass is 6.687×1015 kg, one ten-millionth of the lunar mass. The golden-brown surface appears heavily cratered in photographs. The largest are comparable to Eros itself, a characteristic that it shares with other asteroids. High-resolution images reveal the presence of a layer of regolith that covers the asteroid on all sides and whose thickness is estimated to be between 10 and 100 m.
Among the objects of its size in the solar system, Eros has been the most observed. Historically, its observations were relevant to the determination of the solar parallax (and therefore the astronomical unit) and the mass of the system Earth-Moon. It was the first asteroid around which a space probe has orbited and landed: the NEAR-Shoemaker of NASA entered orbit on February 14, 2000 and landed on February 12, 2001, where it did a chemical analysis of the surface.
History
Discovery and naming
Eros was discovered on August 13, 1898 by Gustav Witt from the Urania observatory in Berlin, Germany, as an object of the eleventh magnitude while making precise astrometric measurements of the position of the asteroid (185) Eunike. The asteroid appeared in a two-hour exposure photographic plate centered on the star Beta Aquarii. The same night, Auguste Honoré Charlois (1864-1910) from the observatory in Nice, France, took images of Eros. However, Charlois published the data a few days after Witt. Initially, the delay was blamed on the French astronomer himself, who was criticized for failing to check the photographic plates in the days immediately following the night of the exposure — on August 14, which was a Sunday, and August 15, which was a holiday in France—. However, the cause of the delay was due to to a technical problem with the telescope that had failed to cancel out the effect of the movement of the Earth and produced a less sharp image. This circumstance, discovered in 2002, has made Charlois the recognized independent discoverer of the asteroid. It was initially designated 1898 DQ and was later named after Eros, a god of Greek mythology. It was the first asteroid to receive a masculine name.
Orbital characteristics
Eros orbits at an average distance from the Sun of 1,458 AU, being able to move away up to 1,783 AU and approach up to 1,133 AU. It has an eccentricity of 0.2226 and an orbital inclination of 10.83°. It takes 643 days to complete one orbit around the Sun. The closest it has reached to Earth was 23 million kilometers on January 23, 1975. January 31, 2012 was the last time it had its closest approach to Earth, being 26.7 million km away. It was the first known asteroid to cross Earth's orbit.
Physical characteristics
It is the second largest near-Earth asteroid after Ganymede. It has an extremely elongated shape, similar to a peanut. It measures 33 km from one end to the other.
Space exploration
In the year 2000, Eros was the first asteroid to be orbited by a space probe, the NEAR Shoemaker, which ended up landing on the asteroid's surface on February 12, 2001 (maneuver for the which the probe was not designed). The probe continued to transmit data from the asteroid's surface until February 28, 2001.
Images of the asteroid
Image of the Southern Hemisphere of Eros
You're seen by NEAR.
You're seen by Celestia.
