03 March 2024 - Mission Day: 10320 - DOY: 063
SOHO's 3000th Comet Contest

Contest Objective

SOHO is approaching the date when its images will reveal its 3000th comet, a record-extending achievement. So we are offering everyone an opportunity to guess when this will happen -- or specifically, guess the date and time of perihelion (closest approach to the Sun) for the comet. The winner and the next two closest guessers will win some nice prizes. The current number of comets discovered by SOHO is around 2890, and we expect to stop taking entries once this number reaches 2950. (We don't know when that will be!)

The information below will give you a record of the discoveries to help you make a more refined guess. Interestingly, about 90% of the comets that SOHO has discovered have been identified by amateurs culling through SOHO data. And you can see some of our favorite comets in the SOHO Gallery.

Contest Rules

    1. The contest is open to anyone, anywhere, except those administering the contest. You must be older than 13 years old to participate. Only one entry per person.

    2. Send in your guess using the form below with the date and time, down to the second. We will use Universal Time in all instances. Entries without a name and valid e-mail address will be discarded.

    3. Entries can only be submitted using this form.

    4. Entries must be received by our cut-off mark, which is when SOHO reaches comet number 2950 - some time in the next couple of months. We will update the totals on this page from time to time.

    5. Karl Battams, the Sungrazer Project coordinator and our SOHO comet expert, will be the final arbiter for the time and date when the 3000th comet reaches perihelion.

    6. Guesses will not be publicized until the entry period has closed.


Follow the Comet Discoveries on Twitter


Besides bragging rights, the winners will receive prizes selected from the following:

Signed copy of Paal Brekke's "The Northern Lights - A Guide X 1" (link). Signed copies of Paal Brekke's DVDs "Northern Lights - a Magic Experience". A DVD copy of PBS’s "Comet Encounter" ISON documentary. A signed copy of Steele Hill's "The Sun" book. NASA pins and patches.

Comet Information

Tips: Possible Strategies

  1. Estimate the number of comets per year and extrapolate (see image on the right).
  2. Refine your estimate by looking at the monthly variation in the rate of discoveries.
  3. Guess.

! Current (May 26, 2015) Comet Count: over 2,950

Click to enlarge

In addition to these statistics and the corresponding plots, the following perihelion dates/times may guide you:
SOHO-500: 2002-Aug-12 16:04UT
SOHO-1000: 2005-Aug-06 02:38UT
SOHO-1500: 2008-Jun-06 09:36UT
SOHO-2000: 2010-Dec-27 08:00UT

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. 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.

• European Site • US Site


Feedback & Comments: SOHO Webmaster

Last modification: July 27, 2020

SOHO is a project of international cooperation between