4581 Asclepius

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4581 Asclepius
Discovered by Henry E. Holt
Norman G. Thomas
Discovery date 31 March 1989
Named after
1989 FC
Apollo asteroid,
Orbital characteristics[1]
Epoch 20 December 2013 (JD 2456646.5)
Uncertainty parameter 0
Observation arc 9628 days (26.36 yr)
Aphelion 1.3875 AU (207.57 Gm)
Perihelion 0.65734 AU (98.337 Gm)
1.0224 AU (152.95 Gm)
Eccentricity 0.35706
1.03 yr (377.60 d)
28.50 km/s
0° 57m 12.24s / day
Inclination 4.9191°
Earth MOID 0.00335152 AU (501,380 km)
Jupiter MOID 3.88524 AU (581.224 Gm)
Jupiter Tisserand parameter 5.914
Physical characteristics
Dimensions 300 m

between 1010 kg and 1011 kg

(rough estimate based on diameter)
Mean density
? g/cm³
Equatorial surface gravity
? m/s²
Equatorial escape velocity
? km/s
? d
Temperature ~275 K

4581 Asclepius (/əˈsklpiəs/ ə-SKLEE-pee-əs) is a small asteroid of the Apollo group that makes close orbital passes with Earth. Discovered in 1989 by American astronomers Henry E. Holt (1929-) and Norman G. Thomas (1930-), Asclepius is named after the Greek demigod of medicine and healing.

Asclepius passed by Earth on March 22, 1989, at a distance of 0.00457 AU (684,000 km; 425,000 mi).[2][3] Although this exceeds the Moon's orbital radius, the close pass received attention at that time, especially since the asteroid passed through the exact position of Earth only six hours earlier. "On the cosmic scale of things, that was a close call," said Dr. Henry Holt.[4] Geophysicists estimate that collision with Asclepius would release energy comparable to the explosion of a 600 megaton atomic bomb.[5] The asteroid was discovered March 31, 1989, nine days after its closest approach to the Earth.[6]

Subsequent discoveries revealed that a whole class of such objects exists. Close approaches by objects the size of Asclepius pass by every two or three years, undetected until the start of computerized near-Earth object searches.

On 24 March 2051, the asteroid will pass 0.0123 AU (1,840,000 km; 1,140,000 mi) from the Earth.[2][3] It will be the eighth pass of less than 30 Gm in this century.[2] JPL shows that the uncertainty region of the asteroid will cause it to mostly likely pass from 0.02 AU to 0.17 AU from the Earth in 2135.[2]


  1. ^ a b "JPL Small-Body Database Browser: 4581 Asclepius (1989 FC)" (2011-07-28 last obs (arc=22.32 years)). Jet Propulsion Laboratory. Retrieved 11 April 2016. 
  2. ^ a b c d "JPL Close-Approach Data: 4581 Asclepius (1989 FC)" (2015-08-10 last obs (arc=26.36 years)). Retrieved 2016-01-09. 
  3. ^ a b "NEODyS-2 Close Approaches for (4581) Asclepius". Near Earth Objects - Dynamic Site. Retrieved 2011-11-08. 
  4. ^ "Asteroid's Passing a 'Close Call' for Earth, NASA Says". Los Angeles Times. April 20, 1989. Retrieved 2010-05-07. 
  5. ^ Gilchrist, Tom (November 2008). "Effects of an impact event: an analysis of asteroid 1989FC". Geoverse: e-journal of Undergraduate Research in Geography. ISSN 1758-3411. Retrieved 2010-05-07. 
  6. ^ Brian G. Marsden (1998-03-29). "How the Asteroid Story Hit: An Aastronomer Reveals How a Discovery Spun Out of Control". Minor Planet Center and Boston Globe newspaper. Retrieved 2011-11-14. 

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