433 EROS

'433 Eros' (ˈirɒs) is an asteroid named after the Greek god of love, Eros (Greek Ἔρως). It is an S-type asteroid approximately 13 × 13 × 33 km in size, the second-largest near-Earth asteroid, belonging to the Amors. It is also a Mars-crosser asteroid. On January 31, 2012, Eros is expected to pass Earth at 0.1790 astronomical units (1 AU – about 93 million miles – is the average distance from Earth to the sun). [1]
At this distance Eros has a visual magnitude much higher than Neptune and brighter than any main belt asteroid except 4 Vesta and, rarely, 2 Pallas and 7 Iris. Under this condition, the asteroid actually appears to stop, but unlike the normal condition for a body in heliocentric conjunction with the Earth, it never appears to be retrograde. Its synodic period of over 846 Earth days is among the largest of any body in the Solar System.
Eros was visited by the NEAR Shoemaker probe, which orbited it, taking extensive photographs of its surface, and, on February 12 2001, at the end of its mission, landed on the asteroid's surface using its maneuvering jets.
The rarely-used adjectival form of the name Eros is ''Erotian'' (ɪˈroʊʃən).

Contents

Physical characteristics

History

Legal controversy

See also

References

External links

Physical characteristics

Surface gravity depends on the distance from a spot on the surface to the center of a body's mass. The Erotian surface gravity varies greatly, since Eros is not a sphere but an elongated peanut-shaped (or potato- or shoe-shaped) object. The daytime temperature on Eros hovers at about 100 °C and nighttime measurements at −150 °C. Eros's density is 2,400 kg/m³, about the same as the density of Earth's crust. It rotates once every 5.27 hours.
NEAR scientists have found that most of the larger rocks strewn across Eros were ejected from a single crater in a meteorite collision approximately 1 billion years ago. This impact may also be responsible for the 40 percent of the Erotian surface that is devoid of craters smaller than 0.5 kilometers across. It was originally thought that the debris thrown up by the collision filled in the smaller craters. An analysis of crater densities over the surface indicates that the areas with lower crater density are within 9 kilometers of the impact point. Some of the lower density areas were found on the opposite side of the asteroid but still within 9 kilometers.
It is theorized that seismic shockwaves propagated through the asteroid, shaking smaller craters into rubble. Since Eros is irregularly shaped, a 9 kilometer straight line through the asteroid can reach locations that would be further away if travelling across the surface, thus leading to the uneven pattern of crater density on the surface. (Thomas & Robinson, 2005)

History

As one of the larger Near Earth Asteroids (NEAs), Eros has played a significant role throughout history. Discovered on the same night (13 August 1898) by Gustav Witt in Berlin and Auguste Charlois at Nice^[1], Eros was the first asteroid that was known to come within the orbit of Mars.
During the opposition of 1900-1901, a world-wide program was launched to make parallax measurements of the asteroid to determine the solar parallax (or distance to the sun), with the results published in 1910 by Arthur Hinks of Cambridge^[2]. A similar program was then carried out, during a closer approach, in 1930-1931 by Harold Spencer Jones^[3]. The value obtained by this program was considered definitive until 1968, when greater faith was placed in radar and dynamical parallax methods.
Eros was one of the first asteroids to be visited by a space craft, with NASA mission NEAR entering its orbit in 2000.

Legal controversy

In an experimental legal case, Eros was claimed as property by Gregory W. Nemitz of OrbDev. According to the Homestead principle, Nemitz argued that he had the right to claim ownership of any celestial body that he made use of; he claimed he had designated Eros a spacecraft parking facility and wished to charge NASA a parking and storage fee of twenty cents per year for NEAR Shoemaker. Nemitz's case was dismissed and an appeal denied. [2]

See also

★ Eros in fiction

★ List of geological features on 433 Eros

References

★ Seismic resurfacing by a single impact on the asteroid 433 Eros, Thomas PC, Robinson MS, , , Nature, 1970 PMID 16034412
1. Scholl, Hans and Lutz D. Schmadel, "Discovery Circumstances of the First Near-Earth Asteroid (433) Eros", ''Beiträge zur Astronomiegeschichte'', vol. 5, p. 210-220 (2002)
2. Hinks, A. R., "Solar Parallax Papers No. 7: The General Solution from the Photographic Right Ascensions of Eros, at the Opposition of 1900", ''Monthly Notices of the Royal Astronomical Society'' v. 69, no. 7, pp. 544 ff. (1910)
3. Jones, H. Spencer, "The Solar Parallax and the Mass of the Moon from Observations of Eros at the Opposition of 1931", ''Memoirs of the Royal Astronomical Society'', v. LXVI, part II (1941)

External links

★ NEAR Shoemaker spacecraft

★ NEAR image of the day archive

★ Movie: NEAR Shoemaker spacecraft landing

★ The Eros Project (OrbDev's attempts at litigation over their property claim)