In August 2014, ESA made history when its Rosetta spacecraft became the first to orbit a comet. Over the past 10 months, Rosetta and its newly reawakened lander Philae have been supplying us with unprecedented data on comet 67P/Churyumov-Gerasimenko since then. Right away, scientists noticed the presence of several enigmatic deep pits on the comet’s surface. New data suggests the pits are sinkholes caused by the sublimation of subsurface ice and are one source of active dust jets. That and data on the composition of the body hint at a comet that’s riddled with underground caverns.
Comets—the leftover pieces of ice and rock from the formation of the Solar System—are like icy time capsules. By studying them, we can learn a great deal about the conditions in the solar nebula—the cloud of gas and dust in which the Sun and the planets formed over 4 billion years ago. Comets come in multiple varieties and have spent their lives in one of two “cold storage” areas in the outer Solar System—the Kuiper Belt and the Oort Cloud.
The Kuiper Belt, a region beyond the orbit of Neptune, is the source of Jupiter-family comets like 67P. This class typically has an orbital period of less than 20 years and is strongly affected by Jupiter’s gravity. Beyond the Kuiper Belt and extending nearly halfway to the nearest star is a spherical region known as the Oort Cloud. This is where we see long-period comets which have orbital periods that can last up to millions of years.
Read 13 remaining paragraphs | Comments
No comments:
Post a Comment