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4450 Pan, provisional designation 1987 SY, is a highly eccentric asteroid and contact binary, classified as a potentially hazardous asteroid and near-Earth object of the Apollo group, approximately 1.1 kilometers in diameter.

4450 Pan
Discovery [1]
Discovered byC. S. Shoemaker
E. M. Shoemaker
Discovery sitePalomar Obs.
Discovery date25 September 1987
MPC designation(4450) Pan
Named after
Pan (Greek deity)[2]
1987 SY · 1937 CA
NEO · Apollo · PHA[1][3]
Orbital characteristics[1]
Epoch 4 September 2017 (JD 2458000.5)
Uncertainty parameter 0
Observation arc78.85 yr (28,799 days)
Aphelion2.2884 AU
Perihelion0.5962 AU
1.4423 AU
1.73 yr (633 days)
0° 34m 8.4s / day
Earth MOID0.0287 AU · 11.2 LD
Physical characteristics
Dimensions1.0±0.2 km[4]
1.13 km (calculated)[5]
3.51±0.02 h[6]
56.48±0.02 h[7]
60±12 h[a]
0.20 (assumed)[5]
17.1[1][5] · 17.43±0.07[4]

The asteroid was discovered on 25 September 1987, by American astronomers Eugene and Carolyn Shoemaker at Palomar Observatory in California, United States.[3] It was named after Pan from Greek mythology.[2]


Orbit and classificationEdit

Pan orbits the Sun in the inner main-belt at a distance of 0.6–2.3 AU once every 1 years and 9 months (633 days). Its orbit has an eccentricity of 0.59 and an inclination of 6° with respect to the ecliptic.[1]

As an Apollo asteroid, it is an Earth-crosser and has a minimum orbit intersection distance with Earth of 0.0287 AU (4,290,000 km), which corresponds to 11.2 lunar distances. Due to its extremely eccentric orbit, it is also a Venus- and Mars-crosser and approaches Mercury within 20 Gm.

It was first identified as 1937 CA at Heidelberg Observatory in 1937. The body's observation arc begins at Palomar with its official discovery observation.[3]

Physical characteristicsEdit

Pan is an assumed stony S-type asteroid.[5]

Contact binaryEdit

Pan is a contact binary, composed of two lobes in mutual contact, held together only by their weak gravitational attraction, and typically show a dumbbell-like shape (also see 4769 Castalia).[8] A large number of near-Earth objects are thought to be contact binaries.[9]

Diameter and albedoEdit

The Collaborative Asteroid Lightcurve Link assumes a standard albedo for stony asteroids of 0.20 and calculates a diameter of 1.1 kilometers,[5] while photometric observations by Italian Albino Carbognani at Saint-Barthelemy Observatory (B04) gave a diameter of 1.0±0.2 kilometers.[4]

Rotation periodEdit

In September 2013, a rotational lightcurve of Pan was obtained from photometric observations by American astronomer Brian Warner at his Palmer Divide Station (716) in Colorado. It gave a long rotation period of 56.48±0.02 hours with a brightness variation of 0.64 in magnitude (U=3).[7]

The results supersedes two previous observations by Petr Pravec at Silvano Casulli that gave a period of 60±12 and 3.51±0.02 hours, respectively (U=2/1).[a][6]


This minor planet was named after Pan, the Greek god of nature, shepherds of flocks and wild animals.[2]

In art, he was represented as a horned half-man, half goat. Pan was worshiped by the citizens of Athens, after he had inspired panic in the hearts of their Persians enemies in the Battle of Marathon (also see 4356 Marathon). The modern word "panic" origins from this myth. The name Pan has also been given to Saturn XVIII, one of the moons of Saturn.[2] The official naming citation was published by the Minor Planet Center on 30 January 1991 (M.P.C. 17657).[10]


  1. ^ a b Pravec (2008) web: rotation period 60±12 hours with a brightness amplitude of 0.6 mag. Summary figures for (4450) Pan at Collaborative Asteroid Lightcurve Link (CALL)


  1. ^ a b c d e "JPL Small-Body Database Browser: 4450 Pan (1987 SY)" (2015-12-13 last obs.). Jet Propulsion Laboratory. Retrieved 20 June 2017.
  2. ^ a b c d Schmadel, Lutz D. (2007). "(4450) Pan". Dictionary of Minor Planet Names – (4450) Pan. Springer Berlin Heidelberg. p. 382. doi:10.1007/978-3-540-29925-7_4395. ISBN 978-3-540-00238-3.
  3. ^ a b c "4450 Pan (1987 SY)". Minor Planet Center. Retrieved 11 August 2016.
  4. ^ a b c Carbognani, Alberto (September 2008). "Lightcurve Photometry of NEAs 4450 Pan, (170891) 2004 TY16 2002 RC118, and 2007 VD12". The Minor Planet Bulletin. 35 (3): 109–110. Bibcode:2008MPBu...35..109C. ISSN 1052-8091. Retrieved 11 August 2016.
  5. ^ a b c d e f "LCDB Data for (4450) Pan". Asteroid Lightcurve Database (LCDB). Retrieved 11 August 2016.
  6. ^ a b Behrend, Raoul. "Asteroids and comets rotation curves – (4450) Pan". Geneva Observatory. Retrieved 11 August 2016.
  7. ^ a b Warner, Brian D. (April 2014). "Near-Earth Asteroid Lightcurve Analysis at CS3-Palmer Divide Station: 2013 September-December". The Minor Planet Bulletin. 41 (2): 113–124. Bibcode:2014MPBu...41..113W. ISSN 1052-8091. Retrieved 11 August 2016.
  8. ^ Lance A. M. Benner (2013-11-18). "Binary and Ternary near-Earth Asteroids detected by radar". NASA/JPL Asteroid Radar Research. Retrieved 2014-03-01.
  9. ^ Michael Busch (2012-03-12). "Near-Earth Asteroids and Radar Speckle Tracking" (PDF). Retrieved 11 August 2016.
  10. ^ "MPC/MPO/MPS Archive". Minor Planet Center. Retrieved 11 August 2016.

External linksEdit