The image you’re referring to is of asteroid 2015 TB145, and it was created using radar data collected by the National Science Foundation’s Arecibo Observatory in Puerto Rico. This radar image was taken on October 30, 2015, and it provides a high-resolution view with a pixel size of 25 feet (7.5 meters).
Scientists who were studying asteroid 2015 TB145 with NASA’s Infrared Telescope Facility (IRTF) in Hawaii have determined that this celestial object is likely a “dead comet.” This means that it was once a comet with a nucleus of ice and dust, but it has lost its volatile materials over time due to repeated orbits around the Sun.
This asteroid, which was previously a comet, was also observed by optical and radar observatories worldwide. These observations provided valuable data, including close-up views of its surface. In terms of its proximity to Earth, asteroid 2015 TB145 had a relatively close encounter, passing by our planet at a distance of just under 1.3 lunar distances, or about 302,000 miles (486,000 kilometers), on Halloween (October 31) in 2015. It serves as an intriguing object for astronomers to study the transformation of a comet into an asteroid-like body as it loses its volatile materials.