NASA’s Spitzer Space Telescope has allowed to establish that the asteroid 3552 Don Quixote is actually a comet. Research on this celestial body belonging to the NEO (near-Earth object) class, one of those whose orbit is close to that of the Earth or crosses it, was coordinated by researchers at Northern Arizona University, Flagstaff, Arizona.
3552 Don Quixote was discovered in 1983 and was included among the Amor asteroids, which are a subset of NEOs whose orbit is close to that of the Earth but don’t cross it. Its orbit is peculiar because it’s so eccentric to bring it beyond Jupiter, a feature typical of comets while asteroids generally have more circular orbits, and that’s convinced some astronomers to study it.
The Spitzer Space Telescope has allowed to observe 3552 Don Quixote at infrareds with a sensitivity impossible to achieve with ground telescopes. The team of astronomers led by Michael Mommert was able to discover that this celestial body had a coma and a tail, though tenuous, with large deposits of carbon dioxide and possibly water ice.
Josua Emery, who works for the University of Tennessee, cooperated in this research by rechecking old pictures of 3552 Don Quixote taken in 2004, when it was at its maximum distance from the Sun. On that occasion, it had neither coma nor tail, as is normal in comets when they are too far away from the Sun. It was also possible to determine that this celestial body is composed of silicate dusts, similar to the dust that is found in comets.
The possibility that Don Quixote 3552 hit the Earth are extremely low, at least in the next few centuries, and this is good because with its almost 19 kilometers (almost 12 miles) of length it’s the third in size among the NEOs. The fact that only now we have understood its nature makes us realize how little we still know about the celestial bodies passing close to Earth.
In the distant past many comets have probably hit the Earth and part of the water on the planet probably came from them. According to one estimate, 3552 Don Quixote contains about one hundred billion tons of water, the amount of a large lake. The solar system is full of comets and other sources of water so when someone will venture into deep space they’ll be available to take.
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