NASA's Hubble Space Telescope caught close-up images of comet 252P or LINEAR just two weeks after its near approach with our planet on March 21.
Although it was at least 3 million miles away from Earth when it passed by, comet 252P made history as one of the closest encounters of any comet. Aside from the moon, the comet is also considered as the closest celestial object ever observed by Hubble.
To accurately measure the size of comets, the celestial objects must be close enough, said astronomer Jian-Yang Li, lead scientist of the project.
Comets are typically only a few kilometers in size. LINEAR is probably less than one kilometer across.
"Comet 252P is one of the smallest comets we know of," said Li.
The photos released recently were taken on April 4 while comet 252P was about 8.7 million miles away from Earth.
Taking advantage of the comet's relatively small distance to Earth and the high spatial resolution of Hubble, astronomers reached 1.6 kilometers per pixel resolution.
Li said this is the highest Hubble resolution for any comet. In comparison, observations on the ground for comet 252P yielded more than 10 times lower resolution than Hubble.
The time-lapse produced by astronomers used frames that were taken between 30 and 50 minutes apart.
The comet's bright light, which was shown to be rotating in a way similar to that of a lighthouse beam, is made up of a jet of dust emitted by the comet while it is being warmed by the sun.
Comets such as 252P are comprised of a core called nucleus — which is in turn made up of ice, dirt and dust — that sublimates into a coma due to the warmth of the sun.
Meanwhile, Li said the March 21 approach and the days after it provided scientists an opportunity to better study the comet.
Li said the team's main goal is to study how comets shrink as they pass around the sun. This will help scientists infer the properties of the building blocks of planets at the early years of the solar system.
Additionally, Comet 252P has a sibling that flew a million miles closer to our planet just a few days behind it, but the little comet was not large or bright enough for a close-up. LINEAR is now 25 million miles away from our planet.
