Text Size

Join in the Search for SOHO's 1,000th Comet
A contest is challenging NASA web visitors to guess which day and at what time the Solar and Heliospheric Observatory (SOHO) spacecraft will find its 1,000th comet. Already the most prolific comet hunter in history, SOHO has found 945 comets as of April 25 and is on track to find its 1,000th sometime this summer. Over 9,000 people have entered the contest since it opened in January and the 960th comet, expected sometime in May, will officially end registration.
SOHO spots comets passing by the Sun.
Image Right: The person who guesses the date and time of the 1,000th comet to be spotted near the Sun wins some great solar prizes. Credit: NASA

Enter the SOHO Site to vote for the date and time that you think the record comet will be observed. The closest person to the time, either before or after the comet reaches its closest point to the Sun (perihelion), wins. Complete contest rules are explained on the link above.

Winners will be announced on the comet page as soon as scientists can match the date and time with the entries. The opportunity to vote will end when SOHO discovers its 960th comet sometime in May. Comet counters will keep the page updated so that you can keep track of how many comets have been discovered at any given time. Only one guess per person is permitted.

SOHO spots comet near the Sun Image Left: Comet Machholz 1 passed within 13 million miles (22 million km) of the Sun, unusually close for a comet. This view from Jan. 2002 not only shows the comet in the upper left, but the planet Venus also appears in the lower right. Click on the image for a large movie, or download a QuickTime version. Credit: NASA/ESA.

The closest guess will net you a package of goodies including the SolarMax DVD, a SOHO T-shirt, solar viewing glasses, and a selection of SOHO materials. Second and third place entries will receive the same package without the DVD.

World Book @ NASA World Book @ NASA
Comet: An icy body that releases gas or dust.
+ View Article
In honor of the event, the SOHO team has pulled together the best images and movies of comets spotted by SOHO. The spacecraft, part of a partnership between NASA and the European Space Agency, observes the Sun from a vantage point of about 1 million miles out in space between the Sun and Earth. It carries 12 instruments including the Large Angle Spectrometric Coronograph (LASCO), which mimics an eclipse in order to study the Sun's corona, or outer atmosphere. As it does this job, LASCO is also able to see comets whizzing through its frame as they pass by the Sun and sometimes plunge into it.

SOHO spots comets passing by the Sun. Image Right: This Kreutz sungrazing comet from April 1998 was observed in the LASCO C2 telescope. This particular class of comets vaporizes as they plunge into the solar atmosphere. Click on the image for movie, or download QuickTime and print resolution still. Credit: NASA/ESA.

To help you out in your guessing, here are a few key dates for SOHO comet discoveries. Teachers can use this as a real-world classroom exercise in extrapolating data and making predictions based on the evidence at hand.

Comet NumberDate
100Feb. 4, 2000
200Aug. 31, 2000
300Mar. 25, 2001
400Feb. 26, 2002
500Aug. 14, 2002
600Apr. 29, 2003
700Dec. 2, 2003
800June 11, 2004
897Jan. 13, 2005

More Information:

Watch the Sun in Real-Time from SOHO
SOHO Spots Flare Within Minutes of the New Year
Best Comet Movies from SOHO
Comet Bradfield
Two Comets Race for the Sun
Comet NEAT
Comet Kudo Fujikawa
Steele Hill
NASA Goddard Space Flight Center