In a new twist to the old song, it’s Santa Claus who had “better watch out” on Christmas Eve, as he shares the night sky with a huge asteroid that will make its closest pass to Earth at about the same time the jolly old fellow is making his annual deliveries.
According to EarthSky, Asteroid 163899 – also known as 2003 SD220 – will pass at a safe distance of about 6,787,600 miles (11 million km) from our planet.
It will be so far away that only professional and advanced amateur astronomers are likely to capture optical images of this giant space rock.
The Christmas Eve asteroid isn’t a newly discovered object. Its name – 2003 SD220 – indicates its discovery year. The Lowell Observatory Near-Earth Object Search (LONEOS) programme in Flagstaff, Arizona discovered the asteroid on September 29, 2003.
The large size of this asteroid is one of its most notable features. Early estimates suggested a size of between 0.7 miles and 1.5 miles (1.1 km to 2.5 km), but the size estimate was revised after recent radar observations from the Arecibo telescope in Puerto Rico. The new observations suggest the asteroid is about 1.25 miles (2 km) long.
The roughly oblong asteroid is thought to have a very slow rotation of about one week. While some other asteroids such as 2015 TB145 (the Halloween asteroid) and 2004 BL86 (January 2015) were visible using 8 telescopes, the Christmas Eve asteroid will be much more difficult to see because of its distance. Astronomers are nevertheless already observing this asteroid using radio telescopes and bouncing radio signals from the space rock’s surface.
The Arecibo Observatory in Puerto Rico studied asteroid 2003 SD220 from December 3 to 17, while the Goldstone Antenna in California is analysing the space rock from December 5 to 20. The asteroid will make its approach to Earth on December 24, 2015, but will return in 2018, NASA astronomer and asteroid expert Lance Benner said in a Goldstone radar observations planning document.
The imminent approach is the first of five encounters by this object in the next 12 years when it will be close enough for a radar detection. 2003 SD220 is on NASA’s NHATS list of potential human-accessible targets, so observations of this object are particularly important.
The Near-Earth Object Human Space Flight Accessible Targets Study (NHATS) is a programme developed to identify those near-Earth objects that may be well-suited for future human-space-flight rendezvous missions. EarthSky indicates that although this is a huge asteroid, there is no danger of a future collision. The orbit of asteroid 2003 SD220 is well known and NASA has verified that the space rock will not pass at any dangerous distance during the next two centuries. Reports from media houses suggesting that this asteroid may cause earthquakes are misleading and incorrect, EarthSky states.