Astronomers using NSF’s 1,000-foot (305-m) Arecibo Observatory in Puerto Rico have captured images of a massive asteroid – designated 2015 TB145 – as it made its closest approach to our planet yesterday.
This image of 2015 TB145 was generated using radar data collected by the Arecibo Observatory. Image credit: NAIC-Arecibo / NSF.
2015 TB145, informally known as the ‘Great Pumpkin’ or the Halloween asteroid, was discovered on October 10, 2015, by astronomers using the University of Hawaii’s Pan-STARRS-1 system.
On October 11, just 12 hours after its discovery, the object was confirmed by astronomers from ESA’s Teide Observatory, Tenerife, Canary Islands.
Yesterday, at approximately 1 p.m. EDT (10 a.m. PDT, 17:00 GMT), the space rock zipped past our planet at a distance of about 302,000 miles (486,000 km), which is further away from Earth than the Moon (1.3 lunar distances).
The newly released images indicate 2015 TB145 is spherical in shape, approximately 2,000 feet (600 m) in diameter, and completes a rotation about once every 5 hours.
“Radar images obtained at the Arecibo Observatory appear to rotate clockwise, which is noticeable by the movement of bright features,” said Dr James Richardson of Arecibo Observatory’s Planetary Radar Group.
“The bright and dark features are indication of surface irregularities. For example, the central dark feature may be a large circular depression, possibly an impact crater.”
This collage of radar images of near-Earth asteroid 2015 TB145 was collected by the Arecibo Observatory on October 30, 2015. The images show the rotation of the space rock, which made its closest approach on October 31 at 1 p.m. EDT (10 a.m. PDT) at a distance of 302,000 miles (486,000 km) – about 1.3 times the distance from Earth to the Moon. Image credit: NAIC-Arecibo / NSF.
According to scientists, the object is likely a dead comet that has shed its volatiles after numerous passes around the Sun.
“We found that 2015 TB145 reflects about 6% of the light it receives from the Sun,” said Dr Vishnu Reddy of the Planetary Science Institute.
“That is similar to fresh asphalt, and while here on Earth we think that is pretty dark, it is brighter than a typical comet which reflects only 3-5% of the light.”
“That suggests it could be cometary in origin – but as there is no coma evident, the conclusion is it’s a dead comet.”
The next time 2015 TB145 will be in Earth’s neighborhood will be in September 2018, when it will make a distant pass at about 24 million miles (38 million km).
“One of the directives of the Arecibo Observatory is to measure with high precision the distance to asteroids and their speed, which can be used to study the asteroid’s orbit and predict its motion for hundreds of years,” said Dr Edgard Rivera-Valentin of the Arecibo Observatory.
“Tracking of 2015 TB145 has shown that it is not a threat and will not have a similarly close approach to Earth during this century.”
