23 July 2024 - Mission Day: 10462 - DOY: 205
The SOHO 2000th Comet Contest


As many of our readers know, SOHO held a 2,000th comet contest to see who could come closest to guessing when the 2000 comet would reach perihelion (closest approach to the Sun). The three closest guesses will be sent some nice solar-related prizes. Comet perihelion time was Dec. 27, 2010 at 0800UT.

And our winners were:

  • Erik Olson of Carpinteria, CA had said it would be 13:36UT that day.
  • Naoto Tatsumi, Okayama, Japan guessed 23:59UT that day.
  • Bill Rankinen of Conneaut, OH guessed Dec. 24 at 18:34UT.

Congratulations to the winners and thanks to all who participated in the contest!


Contest Objective

Predict the date and time that SOHO 2000th -a comet yet to be discovered- will make its closest approach to the Sun (perihelion).

Contest Rules

    1. The contest is open to anyone, anywhere, except those administering the contest.
    2. Entries can only be submitted using this form.
    3. Entry submission will close after the discovey of Comet 1950.
    4. Entries without a name and valid e-mail address will be discarded.
    5. Only one entry per person will be accepted.
    6. In the case of the 2000th comet being an archive discovery, then the discoverer is also not eligible, but the closest guess still wins.
    7. Guesses will not be publicized until the entry period has closed.

The winners will be announced when the 2000th comet has been discovered.

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    First prize:

      - A delightful photo book of the Sun, a signed copy of "The Sun" by Hill and Carlowicz.
      - A "Journey to the Stars" DVD
      - A "SolarMax" DVD

    Second prize:

      - A "SolarMax" DVD
      - A "Journey to the Stars" DVD

    Third prize:

- A "Journey to the Stars" DVD
- SOHO and STEREO posters and a selection of SOHO outreach materials.

Comet Information

Tips: Possible Strategies

    1. Estimate the number of comets per year and extrapolate.
    2. Refine your estimate by looking at the monthly variation in the rate of discoveries.
    3. Consider the chance that the discovery will be an archive claim.
    4. Guess.

    Comet #

    Discovery Date (# of days to next milestone)


    Aug 6 2005 (+256)
    Feb 17 2006 (+235)
    Oct 10 2006 (+216)
    May 14 2007 (+194)
    Nov 24 2007 (+215)
    Jun 26 2008 (+190)
    Jan 2 2009 (+269)
    Sep 28 2009 (+131)
    Feb 6 2010 (+210)
    Nov 5 2010

Notes & Disclaimers

    1. Determination of the SOHO comet numbers is entirely at the discretion of Karl Battams, who maintains the Sungrazer Project. He assigns the numbers in order of discovery, except for archive discoveries which are not necessarily discovered chronologically. These numbers are not an official product of any recognized astronomical body. However, they are a very convenient way to refer to the various comets and to keep track of the total number.
    2. Definition of an archive discovery: This is also at the discretion of Karl Battams. If a comet is reported more than 36 hours after it is first visible in the data (and there are no large gaps in the data), then the comet will be designated as an archive claim. In cases of ambiguity, the 36 hour rule will begin at the time when an average observer might be expected to have been able to find the comet. Following the discovery of SOHO-1950, archive comets will not be counted until after SOHO-2000 is discovered unless it is clear that their inclusion will not unfairly influence the outcome of SOHO-2000.
    3. Neither ESA, NASA, or any other institution associated with SOHO is involved with the adjudication of claims or providing the prize. The contest is designed to increase the public's awareness of SOHO's discoveries and demonstrate the ease of accesibility of scientific data sets by the general public.

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Last modification: July 27, 2020

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