2015 TB145
is a sub-kilometer asteroid, classified as near-Earth object and potentially hazardous asteroid of the Apollo group, approximately in diameter. It safely passed 1.27 lunar distances from Earth on 31 October 2015 at 17:01 UTC, and passed by Earth again in November 2018.
Discovery
The asteroid was first observed on 10 October 2015 by Pan-STARRS at an apparent magnitude of 20 using a Ritchey–Chrétien telescope. The asteroid was not discovered sooner because it spends most of its time beyond the orbit of Mars, has a large orbital inclination, and is usually well below the plane of the ecliptic. The asteroid last passed within of Earth on 29 October 1923 and will not pass that close again until 1 November 2088.The media has nicknamed the asteroid the "Great Pumpkin" after the animated Halloween television special It's the Great Pumpkin, Charlie Brown, "Spooky", the "Halloween Asteroid", and the "Skull Asteroid" due to its human skull-like appearance following radio frequency images taken at Arecibo Observatory and closest approach coincidentally occurring on Halloween day.
2015 flyby
On 31 October 2015 the asteroid passed from the Moon and then passed from Earth.The last approach this close by an object with absolute magnitude brighter than 20 was on 3 July 2006 at 1.1 lunar distances. The next object this large known to pass this close to Earth is that will pass about 1 lunar distance from Earth on 7 August 2027. It is estimated that there are about 2400 near-Earth asteroids 300–500 meters in diameter, of which about 1100 have been discovered.
During closest approach to Earth the asteroid reached about apparent magnitude 10, which is much too faint to be seen by the naked eye. Even at peak brightness, the asteroid was a challenging target for amateur astronomers with small telescopes, best seen in the Northern hemisphere. The glare from an 80% waning gibbous Moon also hindered observations.
At 11:00 UT the asteroid was in the constellation of Taurus about 9 degrees from the Moon and moving at a rate of 3.4 degrees per hour. At the time of closest approach of 17:00 UT the asteroid was in the constellation of Ursa Major about 56 degrees from the Moon and moving at a rate of 14.7 degrees per hour. After closest approach it quickly became too faint and too close to the Sun in the sky to be seen.
2018 flyby
After it had been unobservable for almost three years, was recovered on 7 October 2018 by L. Buzzi at Schiaparelli Observatory, at apparent magnitude 21.The 11 November 2018 flyby was about from Earth.
Observations
Radar imagery
The close approach was studied with radar using Goldstone, the Green Bank Telescope, and the Arecibo Observatory. It was one of the best radar targets of the year with a resolution as high as per pixel. Bistatic radar images created with the Green Bank Telescope had a resolution of per pixel. Arecibo images had a resolution of per pixel.| 30 October | 31 October 12:55–13:08 UTC | 1 November |