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Flight of the Comet

Copyright NASA

Flight of the Comet

This video clip was compiled from images taken by NASA’s EPOXI mission spacecraft during its flyby of comet Hartley 2 on Nov. 4, 2010. During the encounter, the spacecraft and comet whisked past each other at a speed of 12.3 kilometers per second (27,560 miles per hour). The spacecraft came within about 700 kilometers (435 miles) of the comet’s nucleus at the time of closest approach.

“While future generations should have the opportunity to truly explore comets, this flyby gives us an excellent preview of what they will get to enjoy,” said EPOXI principal investigator Michael A’Hearn of the University of Maryland, College Park. “Hartley 2 exceeded all our expectations in not only scientific value but in its stark majestic beauty.”

The video clip of the flyby is comprised of 40 frames taken from the spacecraft’s Medium-Resolution Instrument during the encounter. The first image was taken at about 37 minutes before the time of closest approach at a distance of about 27,350 kilometers (17,000 miles). The last image was taken 30 minutes after closest approach at a distance of 22,200 kilometers (13,800 miles). The spacecraft was able to image nearly 50 percent of [...]

SOHO discovers its 1500th comet

soho-discovers-its-1500th-comet

Copyright ESA

The ESA/NASA SOHO spacecraft has just discovered its 1500th comet, making it more successful than all other comet discoverers throughout history put together. Not bad for a spacecraft that was designed as a solar physics mission.

SOHO’s record-breaking discovery was made on 25 June. The small and faint Kreutz-group comet was discovered by US-based veteran comet hunter and amateur astronomer Rob Matson.

Kreutz-group comets, or sungrazing comets have been observed for many hundreds of years. They travel very close to the Sun (if they were to hit it, they would become ‘sunstrikers’), with perihelion distance less than 0.01 Astronomical Units (the mean distance between the Earth and the Sun), or some 1460000 km.

When it comes to comet catching, the SOlar and Heliospheric Observatory has one big advantage over everybody else: its location. Situated between the Sun and Earth, it has a privileged view of a region of space that can rarely be seen from Earth. From the surface, we can see regions close to the Sun clearly only during an eclipse.

Roughly 85% of SOHO discoveries are fragments from a once-great comet that split apart in a death plunge around the Sun, probably many centuries ago. The [...]

SOHO prepares for comet McNaught

soho-prepares-for-comet-mcnaught

Copyright ESA

Recently, sky watchers in the Northern Hemisphere have been enjoying the sight of Comet McNaught in the twilight sky. Now, solar physicists using the ESA-NASA SOHO spacecraft are getting ready for their view. For four days in January, the comet will pass through SOHO’s line of sight and could be the brightest comet SOHO has ever seen.

As Comet McNaught heads towards its closest approach to the Sun on 12 January 2007, it will disappear from view for earthbound observers, becoming lost in the Sun’s glare. That’s where SOHO comes in. Poised in space between the Earth and Sun, SOHO ceaselessly watches the Sun and objects that pass nearby.

Comet McNaught will pass within a fifth of the distance between the Earth and the Sun. As the comet approaches the Sun, the amount of dust and gas it releases will increase dramatically, causing the comet to become extremely bright. “This might become the brightest comet SOHO has ever seen,” says Bernhard Fleck, SOHO Project Scientist.

The material ejected from the comet forms the tails. There are two tails, the dust tail and the gas – or ion – tail. The dust tail is the brighter and is formed [...]

Rosetta – a new target to solve planetary mysteries

rosetta-a-new-target-to-solve-planetary-mysteries

Copyright ESA

ESA INFO 01-2004. Rosetta is scheduled to be launched on board an Ariane-5 rocket on 26 February from Kourou, French Guiana.

Originally timed to begin about a year ago, Rosetta’s journey had to be postponed, as a precaution, following the failure of a different version of Ariane-5 in December 2002. This will be the first mission to orbit and land on a comet, one of the icy bodies that travel throughout the Solar System and develop a characteristic tail when they approach the Sun.

This delay meant that the original mission’s target, Comet Wirtanen, could no longer be reached. Instead, a new target has been selected, Comet 67P/Churyumov-Gerasimenko, which Rosetta will encounter in 2014 after a ‘billiard ball’ journey through the Solar System lasting more than ten years. Rosetta’s name comes from the famous ‘Rosetta Stone’, from which Egyptian hieroglyphics were deciphered almost 200 years ago. In a similar way, scientists hope that the Rosetta spacecraft will unlock the mysteries of the Solar System.

Comets are very interesting objects for scientists, since their composition reflects how the Solar System was when it was very young and still ‘unfinished’, more than 4600 million years ago. Comets have not changed [...]