Hubble Brings Faraway Comet ISON Into View
Comet may be among night sky's brightest lights this fall.
The NASA Hubble Space Telescope has given astronomers their clearest view yet of Comet ISON, a newly-discovered sun grazer comet that may light up the sky later this year, or come so close to the Sun that it disintegrates. A University of Maryland-led research team is closely following ISON, which offers a rare opportunity to witness a comet’s evolution as it makes its first-ever journey through the inner solar system.
Like all comets, ISON is a “ dirty snowball” – a clump of frozen gases mixed with dust, formed in a distant reach of the solar system, traveling on an orbit influenced by the gravitational pull of the Sun and its planets. ISON’s orbit will bring it to a perihelion, or maximum approach to the Sun, of 700,000 miles on November 28, said Maryland assistant research scientist Michael S. Kelley.
This image was made on April 10, when ISON was some 386 million miles from the Sun – slightly closer to the Sun than the planet Jupiter. Comets become more active as they near the inner solar system, where the Sun’s heat evaporates their ices into jets of gases and dust. But even at this great distance ISON is already active, with a strong jet blasting dust particles off its nucleus. As these dust particles shimmer in reflected sunlight, a portion of the comet’s tail becomes visible in the Hubble image.
Next week while the Hubble still has the comet in view, the Maryland team will use the space telescope to gather information about ISON’s gases.
“We want to look for the ratio of the three dominant ices, water, frozen carbon dioxide, and frozen carbon monoxide, or dry ice,” said Maryland astronomy Prof. Michael A’Hearn. “That can tell us the temperature at which the comet formed, and with that temperature, we can then say where in the solar system it formed.”
The Maryland team will use both the Hubble Space Telescope and the instruments on the Deep Impact space craft to continue to follow ISON as it travels toward its November close up (perihelion) with the sun.
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The University of Maryland is the state's flagship university and one of the nation's preeminent public research universities. Ranked among the top 20 public universities by U.S. News & World Report for 11 straight years, it has 25 undergraduate and graduate programs in the top 10 and 72 in the top 25. The Institute of Higher Education (Jiao Tong University, Shanghai), which ranks the world's top universities based on research, puts Maryland at No. 38 in the world and No. 13 among U.S. public universities. For the fourth consecutive year, the University of Maryland ranked in the top 10 of Kiplinger's Personal Finance magazine's list of Best Values in Public Colleges for 2011-12.The university has produced six Nobel laureates, seven Pulitzer Prize winners, more than 40 members of the national academies and scores of Fulbright scholars. The university is recognized for its diversity, with underrepresented students comprising one-third of the student population. For more information about the University of Maryland, visit www.umd.edu.