1862 Apollo

1862 Apollo /əˈpɒloʊ/ is a stony asteroid, approximately 1.5 kilometers in diameter, classified as a near-Earth object (NEO). It was discovered by German astronomer Karl Reinmuth at Heidelberg Observatory on 24 April 1932, but lost and not recovered until 1973.

1862 Apollo

A three-dimensional model of 1862 Apollo based on its light-curve
Discovery[1]
Discovered by	K. Reinmuth
Discovery site	Heidelberg Obs.
Discovery date	24 April 1932
Designations
MPC designation	(1862) Apollo
Pronunciation	/əˈpɒloʊ/[2]
Named after	Apollo (Greek mythology)
Alternative designations	1932 HA
Minor planet category	NEO · PHA Venus-crosser Mars-crosser Apollo asteroids
Symbol	(astrological)
Orbital characteristics[1]
Epoch 29 December 2009 (JD 2455194.5)
Uncertainty parameter 0
Observation arc	85.32 yr (31162 days)
Earliest precovery date	13 December 1930
Aphelion	2.2935 AU (343.10 Gm)
Perihelion	0.64699 AU (96.788 Gm)
Semi-major axis	1.4702 AU (219.94 Gm)
Eccentricity	0.55994
Orbital period (sidereal)	1.78 yr (651.15 d)
Mean anomaly	144.22°
Mean motion	0° 33m 10.332s / day
Inclination	6.3530°
Longitude of ascending node	35.739°
Argument of perihelion	285.85°
Earth MOID	0.0257026 AU (3.84505 Gm)
Jupiter MOID	3.06837 AU (459.022 Gm)
TJupiter	4.415
Physical characteristics
Dimensions	1.5 km (0.93 mi)[3]
Mean radius	0.75 km
Synodic rotation period	3.065 h (0.1277 d)
Geometric albedo	0.25[1][3]
Surface temp. min mean max Kelvin[4] 171 K 214 K 322 K Celsius -102°C -59°C 49°C Fahrenheit -151.6°F -74.2°F 120.2°F
Spectral type	Q (Tholen, SMASS) B–V = 0.819 U–B = 0.481
Absolute magnitude (H)	16.25[1]

It is the namesake and the first recognized member of the Apollo asteroids, a subgroup of NEOs which are Earth-crossers, that is, they cross the orbit of the Earth when viewed perpendicularly to the ecliptic plane (crossing an orbit is a more general term than actually intersecting it). In addition, since Apollo's orbit is highly eccentric, it crosses the orbits of Venus and Mars and is therefore called a Venus-crosser and Mars-crosser as well.

Although Apollo was the first Apollo asteroid to be discovered, its official IAU-number (1862) is higher than that of some other Apollo asteroids such as 1566 Icarus, because it was a lost asteroid for more than 40 years and other bodies were numbered in the meantime. The analysis of its rotation provided observational evidence of the YORP effect.^[5]

It is named after the Greek god Apollo. He is the god of the Sun, child of Zeus and Leto, after which the minor planets 5731 Zeus and 68 Leto are named.^[6]

Satellite

On November 4, 2005, it was announced that an asteroid moon, or satellite of Apollo, had been detected by radar observations from Arecibo Observatory, Puerto Rico, October 29 – November 2, 2005. The announcement is contained in the International Astronomical Union Circular (IAUC) 8627.^[7] The satellite is only 80 m (260 ft) across and orbits Apollo just 3 km (1.9 mi) away from the asteroid itself.^[8] From the surface of Apollo, S/2005 (1862) 1 would have an angular diameter of about 2.0835 degrees.^[a]

Potentially hazardous object

1862 Apollo is a potentially hazardous asteroid (PHA) because its minimum orbit intersection distance (MOID) is less than 0.05 AU and its diameter is greater than 150 meters. Apollo's Earth MOID is 0.0257 AU (3,840,000 km; 2,390,000 mi).^[1] Its orbit is well-determined for the next several hundred years. On 17 May 2075 it will pass 0.0083 AU (1,240,000 km; 770,000 mi) from Venus.^[1]

See also

• Lost asteroid

Notes

1. Calculated from the formula ${\displaystyle \delta }$ = (206265) d / D arcseconds. (see Angular diameter)