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4034 Vishnu
Discovery
Discovered by	E. F. Helin
Discovery site	Palomar Obs.
Discovery date	2 August 1986
Designations
MPC designation	(4034) Vishnu
Named after	Vishnu (Hindu deity)
Alternative designations	1986 PA
Minor planet category	Apollo · NEO · PHA
Orbital characteristics
	Epoch 6 January 2010 (JD 2455202.5)
	Uncertainty parameter 0
Observation arc	28.93 yr (10,565 days)
Aphelion	1.5299 AU
Perihelion	0.5891 AU
Semi-major axis	1.0595 AU
Eccentricity	0.4439
Orbital period (sidereal)	1.09 yr (398 days)
Mean anomaly	62.851°
Mean motion	0° 54m 13.32s / day
Inclination	11.170°
Longitude of ascending node	158.01°
Argument of perihelion	296.60°
Earth MOID	0.0194 AU · 7.6 LD
Physical characteristics
Mean diameter	0.42 km
Geometric albedo	0.52
Spectral type	SMASS = O
Absolute magnitude (H)	18.4

4034 Vishnu (prov. designation: 1986 PA) is a rare-type asteroid classified as near-Earth object and potentially hazardous asteroid of the Apollo group, approximately 420 meters (1,400 feet) in diameter. It was discovered on 2 August 1986, by American astronomer Eleanor Helin at Palomar Observatory in California, United States. It is named after the Hindu deity Vishnu.^[2]

Naming

This minor planet was named for the four-armed god of protection and preservation of good, Vishnu, one of the principal deities of Hinduism. The asteroid's name was proposed by Belgian amateur astronomer and professional meteorologist Jean Meeus.^[2]^[4] The approved naming citation was published by the Minor Planet Center on 15 July 2011 (M.P.C. 75547).^[5]

Classification and orbit

Vishnu orbits the Sun at a distance of 0.6–1.5 AU once every 1 years and 1 month (398 days). Its orbit has an eccentricity of 0.44 and an inclination of 11° with respect to the ecliptic.^[1] As no precoveries were taken, and no prior identifications were made, the body's observation arc begins with its official discovery observation at Palomar in 1986.^[2]

Vishnu is a potentially hazardous asteroid due to its sufficiently large size and low Earth minimum orbital intersection distance of 0.0194 AU (2,900,000 km), which corresponds to 7.6 lunar distances.^[1]

Its highly eccentric orbit crosses the orbits of all inner planets except that of Mercury, which effectively makes it a Venus-crosser, Earth-crosser and Mars-crosser all at once. From 1800 to 2200, Vishnu has made and will make multiple approaches of Venus (71×), Earth (29×), and Mars (7×) within 30 gigameters. It has been observed by radar astronomy (Binzel) and the orbital solution includes non-gravitational forces.^[1]

Physical parameters

In the SMASS taxonomy, Vishnu is a rare O-type asteroid, meaning it is similar to the asteroid 3628 Boznemcová, which is the best asteroid match to the spectra of L6 and LL6 ordinary chondrite meteorites. These L and LL chondrites have lower iron metal content, but higher iron oxide content in the silicates.^[1]

In the early 2000s, Vishnu has been observed in the thermal-infrared by the Keck telescope on Mauna Kea, Hawaii. The asteroid measures approximately 420 meters in diameter and its surface has a high albedo of 0.520.^[3] As of 2017, Vishnu's rotation period and shape remain unknown as no lightcurves have yet been obtained.^[6]