|Discovered by||Henry E. Holt
Norman G. Thomas
|Discovery date||March 31, 1989|
|Alternative names||1989 FC|
|Minor planet category||Apollo asteroid|
|Aphelion||1.387 AU (206.1 Gm)|
|Perihelion||0.6573 AU (98.33 Gm)|
|Semi-major axis||1.022 AU (152.9 Gm)|
|Orbital period||377.6 d (1.03 yr)|
|Average orbital speed||28.50 km/s|
|Longitude of ascending node||180.3°|
|Argument of perihelion||255.2°|
|Mean density||? g/cm³|
|Equatorial surface gravity||? m/s²|
|Escape velocity||? km/s|
|Rotation period||? d|
|Absolute magnitude (H)||20.4|
4581 Asclepius (// 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). 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. Geophysicists estimate that collision with Asclepius would release energy comparable to the explosion of a 600 megaton atomic bomb. The asteroid was discovered March 31, 1989, nine days after its closest approach to the Earth.
Subsequent discoveries revealed that a whole class of such objects exists. Close approaches by objects the size of Asclepius were passing by undetected once every two or three years until the start of computerized near-Earth object searches.
On 2051-Mar-24 the asteroid will pass 0.012 AU (1,800,000 km; 1,100,000 mi) from the Earth. It will be the eighth pass of less than 30 Gm in this century. Due to many close approaches to Earth and Venus that increase the uncertainty region, neither JPL or NEODyS list close approaches after 2127. JPL shows that the uncertainty region of the asteroid will cause it to mostly likely pass from 0.06 AU to 0.24 AU from the Earth in 2127.
- "JPL Small-Body Database Browser: 4581 Asclepius (1989 FC)". Jet Propulsion Laboratory. 2011-07-28 last obs (arc=22.32 years). Retrieved 2011-11-14.
- "JPL Close-Approach Data: 4581 Asclepius (1989 FC)". 2011-07-28 last obs (arc=22.32 years). Retrieved 2011-11-12.
- "NEODyS-2 Close Approaches for (4581) Asclepius". Near Earth Objects - Dynamic Site. Retrieved 2011-11-08.
- "Asteroid's Passing a 'Close Call' for Earth, NASA Says". Los Angeles Times. April 20, 1989. Retrieved 2010-05-07.
- 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.
- 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.