A spooky asteroid will invade the Halloween sky as it passes close by Earth, just a little over 100,000 kilometers (62,000 miles) from the orbit of the moon, making it possible for amateur astronomers to get a glimpse of the celestial body.
Asteroid 2015 TB145, nicknamed “Spooky,” was spotted on October 10, 2015 by the Panoramic Survey Telescope & Rapid Response System (Pan-STARRS), located on Hawaii’s Mount Haleakala. On October 31, a 400 meter-wide (1,300 ft) asteroid will pass near our moon and then the Earth, traveling at about 126,000 kilometers per hour (78,000 miles per hour).
At the time of its closest proximity to Earth, “Spooky” will fly within about 486,800 kilometers (300,000 miles) of our planet – some 1.27 Lunar Distances (LD) away. A few hours before that it will approach the moon, at a distance of about 286,000 km (178,000 miles)
“The trajectory of 2015 TB145 is well understood,” said Paul Chodas, manager of the Center for Near Earth Object Studies at NASA's Jet Propulsion Laboratory, Pasadena, California. “At the point of closest approach, it will be no closer than about 300,000 miles – 480,000 kilometers or 1.3 lunar distances.”
Because of the asteroid’s trajectory, close to our planet, ESA and NASA have classified “Spooky” as a Near-Earth Object and have included it in the list of potentially hazardous asteroids, or those that come within 7.5 million km (4.7 million miles) of Earth.
NASA’s Near-Earth Object Observation Program had listed a total of 1,605 discovered potentially hazardous asteroids, as of 1 August 2015. But the TB145 path remains harmless as it will miss both Earth and the Moon.
However the closely asteroid encounter will be quite a treat for a Halloween night, as “Spooky” is the closest known flyby by a large asteroid until 2027. In 12 years from now an 8,000-meter asteroid, 1999 AN10, will come within 383,000 km (237,000 miles) of Earth.
“Even though that is relatively close by celestial standards, it is expected to be fairly faint, so night-sky Earth observers would need at least a small telescope to view it,” Chodas said.
Astronomers however see it as a rare opportunity to better acquaint themselves with the celestial guest and examine its physical attributes, such as surface features, shape, and dimensions.
“The close approach of 2015 TB145 at about 1.3 times the distance of the moon's orbit, coupled with its size, suggests it will be one of the best asteroids for radar imaging we'll see for several years,” said Lance Benner, of JPL, who leads NASA's asteroid radar research program. “We plan to test a new capability to obtain radar images with two-meter resolution for the first time and hope to see unprecedented levels of detail.”
The research community watching the asteroid are curious about its unusual orbit, as it looks more like the orbit of a comet rather than an asteroid.
“The asteroid’s orbit is very oblong with a high inclination to below the plane of the solar system,” said Lance Benner, who leads NASA’s asteroid radar research program. “Such a unique orbit, along with its high encounter velocity – about 35 kilometers or 22 miles per second – raises the question of whether it may be some type of comet.”