A “Halloween” asteroid that will pass close to Earth today could actually be a dead comet, according to research by Vishnu Reddy of the Planetary Science Institute.
Today, 2015 TB145, which was considered a potentially hazardous object, will pass the Earth as close as 482,803 kilometres (300,000 miles), or just 25 per cent beyond the Moon’s orbit. Understanding the composition of these objects is important to understand how such threats might be mitigated, but also from where in the Solar System they originated. The asteroid, 600 metres in diameter, poses no threat to Earth at this time.
On 30 October, Reddy, a Planetary Science Institute Research Scientist in Tucson, Arizona, captured the body’s spectrum and determined it to be similar to dark carbonaceous meteorites. Astronomers had suggested that the body could be a comet based on its orbit.
“We found that the object reflects about six per cent of the light it receives from the Sun. That is similar to fresh asphalt, and here on Earth we think that is pretty dark, but it is brighter than a typical comet which reflects only three to five per cent of the light,” says Reddy, who made his observations using the NASA Infrared Telescope Facility on Maunakea, Hawaii. “That suggests it could be cometary in origin – but as there is no coma evident, the conclusion is it is a dead comet.”
The object known as 2015 TB145 presents a rare opportunity to study a potentially hazardous object up close. By knowing what it is made of, we can plan for future encounters with asteroids that pose a real threat.
The ‘dead comet’ will safely fly by our planet at 5:01pm (GMT) [1:01pm EDT (10:01am PDT)].