Free Astronomy Magazine July-August 2019

36 JULY-AUGUST 2019 SPACE CHRONICLES vided researchers with new insight into asteroid Gault’s unusual past. The object is 4–9 kilometres wide and has two narrow, comet-like tails of debris that tell us that the asteroid is slowly undergoing self- destruction. Each tail is evidence of an active event that released mate- rial into space. Gault was discovered in 1988. How- ever, this observation of two debris tails is the first indication of the as- teroid’s instability. This asteroid one of only a handful to be caught disintegrating by a process known as a YORP torque. When sunlight heats an asteroid, the infrared radi- ation that escapes from its warmed surface carries off both heat and momentum. This creates a small T hanks to an impressive collab- oration bringing together data from ground-based tele- scopes, all-sky surveys and space- based facilities — including the Hubble Space Telescope — a rare self-destructing asteroid called 6478 Gault has been observed. Clear images from the NASA/ESA Hubble Space Telescope have pro- by NASA/ESA Hubble captures rare active asteroid