Hubble has been an unmatchable resource for interstellar and intergalactic astronomy, but its skills can also be incredible fornearby objects.
In this latest case, astronomers from the Planetary Science Institute (PSI) used the space telescope to obtain high-resolution images of Comet 252P/LINEAR, a periodic comet that orbits between the orbits of Earth and Jupiter.
The comet's closest approach to the Sun was on March 21 this year, and astronomers took this chance to observe it. The images reached a resolution of 1.6 kilometers (1 mile) per pixel, 10 times sharper than any previous ground-based observation of this comet.
“Comet 252P is one of the smallest comets we know of. Our main goal is to determine its size and study how comets become smaller and smaller as they pass around the Sun,” said PSI Senior Scientist Jian-Yang Li, who led the project, in a statement.
“From this we will infer the properties of building blocks of planets at the start of the Solar System. In addition, we will also study other dynamic properties of the comet, such as its rotation and how it releases dust under the heating of the Sun.”
The narrow jet is clearly visible in in these three images of Comet 252P/LINEAR. NASA / ESA / J.-Y. Li (Planetary Science Institute).
The images show how active the small nucleus became with a narrow, well-defined jet of dust seen ejected by the comet. But it's increased distance from the Sun means the comet is now too small to produce a large tail.
252P/LINEAR was most likely an object that originated very near Jupiter, with the giant planet creating such a great perturbation that for the last 400 years its orbit has stretched further and further towards the Sun. Now the comet comes around every 16 years, and this time it was only 5.5 million kilometers (3.3 million miles) from us, about 14 times the Earth-Moon distance.
“Because comets are usually only a few kilometers in size, and probably less than 1 kilometer for this comet, reliable measurement of size is best done when they are close to us,” said Li. “That’s why the close approach to Earth of this comet offered us a great opportunity to study it.”