A giant asteroid designated 2015 TB145 will zip by the Earth on Oct. 31 at around 1.3 lunar distances (LD) - approximately 310,000 miles. The space rock, about 1,542 feet in diameter, was recently spotted by NASA's Pan-STARRS I survey. The space research team expects the asteroid to fly by our planet with a speed of 78,000 mph. 2015 TB145 is the biggest known asteroid to sweep near Earth until 2027.
The closest approach will occur at 11:14 a.m. ET (15:14 UTC). The asteroid is following an eccentric and high-inclination orbit, which may help explain why it was not discovered until Oct. 10 this year.
"The asteroid is on an extremely eccentric and a high inclination orbit," NASA said in a statement. "Its absolute magnitude of 19.9 indicates that its diameter is probably within a factor of two of 320 meters."
Amateur astronomers may be able to see the moving asteroid in telescopes of 8″ in diameter or larger. The asteroid will be traveling across the constellation of Orion.
NASA hopes to obtain high resolution images of the asteroid as it passes. The radio astronomy installations at both DSN Goldstone, California and the Arecibo array in Puerto Rico intend to track and record the path of 2015 TB145 via radar, which should provide invaluable data for future near-Earth asteroid encounters.
"We hope to obtain images with a range resolution as high as 2 m/pixel using DSS-13 to transmit and Green Bank (and possibly Arecibo) to receive. The flyby presents a truly outstanding scientific opportunity to study the physical properties of this object," the space agency said.
NASA describes the 2015 TB145 as potentially “hazardous,” although they are sure that it poses no danger and will not hit Earth.
This is the closest approach by a known object this large until 1999 AN10 approaches within 1 LD in August 2027.
As of Oct. 20, 2015 there were 1629 potentially hazardous asteroids (PHAs). PHAs are space rocks larger than approximately 100 meters that can come closer to Earth than 0.05 AU. None of the known PHAs is on a collision course with our planet, although astronomers are finding new ones all the time.