A lot of people think that astronomy is as simple as taking nice images, looking at them, and then getting good science. The reality is that a whole lot of work goes into processing images to figure out where the science is hiding. 

The ATLAS team, for instance, goes to all kinds of measures to find and study comets and asteroids. To find things, they will take image after image of the same field, process them to get the sky levels identical, despite changing moonlight and other factors, and then subtract images from one another so the stars disappear while moving objects pop out to be seen. They will then combine images so that stars appear to streak while moving objects appear as single points that can be more easily seen. These processes are what found the recently self-destructed Comet ATLAS. It is also the process that found asteroid 2019 LD2, an object that refuses to behave as an asteroid should.  

Found out near Jupiter last June and classified as a Trojan asteroid, 2019 LD2 grew itself a tiny tail as volatile materials got heated by the sun and pushed away by the solar wind. This tail was confirmed last July, and its development was followed until geometry took this active asteroid out of our view and hid it behind the Sun. Now visible again, the team has once again confirmed that this is an asteroid with a tiny tail, and it has been active for roughly a year. While periodic activity has been observed in other objects, such as the rock-throwing Bennu, this long a period of activity hasn’t been seen before. It is unclear why LD2 is so active, but, to quote the press release, “Maybe Jupiter captured it only recently from a more distant orbit where surface ice could still survive. Maybe it recently suffered a landslide or an impact from another asteroid, exposing ice that used to be buried under layers of protective rock. New observations to find out are being acquired and evaluated.” 

More Information

University of Hawai’i Institute for Astronomy press release