Wednesday, May 13, 2020

Asteroid 6489 Golevka Has Two Close Earth Approaches in 21st Century


Summary: Apollo asteroid 6489 Golevka has two close Earth approaches in the 21st century, but neither approach is considered potentially hazardous.


Apollo asteroid 6489 Golevka made its first close Earth approach of the 20th century on Tuesday, May 20, 2003: Courtesy NASA/JPL-Caltech, May be used for any purpose without prior permission, via NASA JPL Solar System Dynamics

Apollo asteroid 6489 Golevka has two close Earth approaches in the 21st century, but, at distances of greater than 0.05 astronomical units (7,479,893.53 kilometers), neither approach poses potential hazards to Earth.
American astronomer Eleanor Francis “Glo” Helin (Nov. 19, 1932-Jan. 25, 2009) discovered 6489 Golevka on Friday, May 10, 1991, at southwestern California’s Palomar Observatory about one month before the asteroid’s first potentially hazardous close Earth approach of the 20th century. The International Astronomical Union (IAU), which authorizes astronomy’s designations and names, recognizes Helin’s discovery under the official citation of 6489 Golevka and under its temporary designation of 1991 JX.
The NASA (National Aeronautics and Space Administration) Jet Propulsion Laboratory (JPL) Solar System Dynamics (SSD) website classifies 6489 Golevka as an Apollo asteroid. The NASA JPL’s Center for Near Earth Object Studies (CNEOS) website defines Apollos as near-Earth asteroids with perihelion (Ancient Greek: περί, perí, “near” + ἥλιος, hḗlios, “sun”) distances of less than 1.017 astronomical units (152,141,034.50 kilometers) and major semi-axes at greater than 1.0 astronomical unit (149,597,870.7 kilometers). (Also known as the semi-major axis, the major semi-axis equates to half of an elliptical orbit’s longest diameter.)
Golevka also classifies as a potentially hazardous asteroid (PHA). The NASA JPL CNEOS website defines PHAs as near-Earth asteroids with an Earth Minimum Orbit Intersection Distance (MOID) of 0.05 astronomical units (au) or less and with an absolute magnitude (H) of 22.0 or less. CNEOS explains the absolute magnitude of asteroids and planets, commonly designated as H, as the object’s apparent, or visual, magnitude under an ideal solar opposition of zero, or full, phase angle and at a distance of one astronomical unit from both the observer and the sun. The CNEOS website registers Golevka’s absolute magnitude (H) at 19.2 for the asteroid’s two potentially hazardous approaches in the 20 century and its single potentially hazardous approach in the 22nd century.
A report by Washington State University professor of electrical engineering and computer science Raymond Scott Hudson (born 1959) and 26 co-researchers on NASA-funded radar observations in June 1995 during Golevka’s second 20th century close Earth approach includes a table of Golevka’s close approaches “to within 0.1 AU of inner Solar System bodies” (page 41). Between the 17th and 29th centuries, the asteroid tallies 36 close approaches. Earth experiences 25 close approaches, of which 11 pose potential hazards. The asteroid nears Mars in 11 approaches, of which five calculate at less than 0.05 astronomical units.
The close planetary approach table provided by Hudson et al. details the century’s first of two close Earth approaches as having occurred on Julian date 2452780.17251. The date equates to Tuesday, May 20, 2003, at 16:08:24.9 UT1 (Universal Time 1, UT’s principal form), according to the U.S. Naval Observatory Astronomical Applications Department’s Julian Date Converter.
The May 2003, close Earth approach was distanced at 0.092265 au (13,802,647.54 kilometers). Astronomy’s measure of solar system distances in terms of astronomical units is based on the distance between the sun and Earth. The IAU precisely values one astronomical unit at 149,597,870,700 meters (149,597,870.7 kilometers).
The asteroid’s second close Earth approach in the 21st century takes place on Julian date 2468479.72649. Converted to UT1, the event is expected on Monday, May 14, 2046, at 05:26:08.7. The asteroid’s center-to-center distance with Earth is calculated at 0.050800 au (7,599,571.83 kilometers).
The 21st century’s absence of potentially hazardous approaches succeeds the 20th century’s threats of two possibly threatening approaches. The first potentially hazardous approach happened approximately one month after the asteroid’s discovery. Golevka’s reach of 0.033185 au (4,964,405.33 kilometers) occurred on Julian date 2448419.30338 (Tuesday, June 11, 1991, at 19:16:52.0 UT1). The century’s second potentially hazardous approach, during which NASA-funded research grants made radar observations of Golevka, took place on Julian date 2449877.59441 (Friday, June 9, 1995, at 02:15:57.0 UT1). The asteroid logged a distance of 0.034106 au (5,102,184.97 kilometers).
The takeaways for Apollo asteroid 6489 Golevka’s two close Earth approaches in the 21st century is that, with distances of more than 0.05 astronomical units in May 2003 and in May 2046, Golevka poses no potential threat to Earth.

Golevka was released April 7, 2005, by Swiss post-rock band The Evpatoria Report; the band's name honors Western Crimea’s Evpatoria RT-70 radio telescope, which joined the Goldstone antenna in California and the Kashima antenna in Japan in conducting the first intercontinental radar astronomy experiments during asteroid 6489 Golevka’s potentially hazardous close Earth approach in June 1995; album cover designed by Swiss designer Fabian Sbarro, eldest son of Italian-born Swiss concept car designer Francesco “Franco” Zefferino Sbarro (born Feb. 27, 1939): Post-Rock Egypt @postrockX, via Twitter April 7, 2019

Acknowledgment
My special thanks to talented artists and photographers/concerned organizations who make their fine images available on the internet.

Image credits:
Apollo asteroid 6489 Golevka made its first close Earth approach of the 20th century on Tuesday, May 20, 2003: Courtesy NASA/JPL-Caltech, May be used for any purpose without prior permission, via NASA JPL Solar System Dynamics @ https://ssd.jpl.nasa.gov/sbdb.cgi?sstr=6489;old=0;orb=1
Golevka was released April 7, 2005, by Swiss post-rock band The Evpatoria Report; Laurent Quint, Simon Robert, David Di Lorenzo, Fabrice Berney and Daniel Bacsinszky named their band after Western Crimea’s Evpatoria RT-70 radio telescope, which joined the Goldstone antenna in California and the Kashima antenna in Japan in conducting the first intercontinental radar astronomy experiments during asteroid 6489 Golevka’s potentially hazardous close Earth approach in June 1995; album cover designed by Swiss designer Fabian Sbarro, eldest son of Italian-born Swiss concept car designer Francesco “Franco” Zefferino Sbarro (born Feb. 27, 1939): Post-Rock Egypt @postrockX, via Twitter April 7, 2019, @ https://twitter.com/postrockX/status/1114906745250439168

For further information:
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