With the help of the NASA/ESA Hubble Space Telescope, a group of astronomers observed an unusual object in the asteroid belt between Mars and Jupiter. The 2 asteroids were seen orbiting each other and exhibiting features similar to the comets: Bright coma and Long tail. The findings were published in Science journal 'Nature' on 20 September 2017. The website 'Science Daily' reported, "This is the first known binary asteroid also classified as a comet".

The website said, "In September 2016, just before the asteroid 288P made its closest approach to the Sun, it was close enough to Earth allowing astronomers to have a detailed look at it using the Hubble Space Telescope. The images of 288P, which is located in the asteroid belt between Mars and Jupiter, revealed that it was actually not a single object, but 2 asteroids of almost the same mass and size, orbiting each other at a distance of about 100 km. That discovery was in itself an important finding and because they orbit each other, the masses of the objects in such systems can be measured".

Jessica Agarwal of the Max Planck Institute for Solar System Research, Germany, also the leader of the team of astronomers and main author of the 'Nature' paper, is quoted by the website as saying, "We detected strong indications of the sublimation of water ice due to the increased solar heating -- similar to how the tail of a comet is created". 288P is thus the 1st known binary asteroid also classified as a "main-belt comet".

Jessica Agarwal explains that observing 288P could yield information about its past. "Surface ice cannot survive in the asteroid belt for the age of the Solar System but can be protected for billions of years by a refractory dust mantle, only a few metres thick," she is quoted as saying by the website. The team has estimated that the 288P has existed as a binary system for only about 5000 years. The astronomer explained, "The most probable formation scenario of 288P is a breakup due to fast rotation. After that, the 2 fragments may have been moved further apart by sublimation torques".