NASA, ESA solar observatory discovers 4,000th comet

A citizen scientist spotted it, with data from the Solar and Heliospheric Observatory, or SOHO.

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The 4,000th comet was discovered by NASA and the ESA's solar observatory.

ESA/NASA/SOHO/Karl Battams

A citizen scientist on Monday found a never-before-seen comet with data from the Solar and Heliospheric Observatory, or SOHO, making it the 4,000th comet to be discovered in the 25-year lifespan of the spacecraft. 

The comet, which is being called SOHO-4000 until its official designation from the Minor Planet Center, has a diameter of between 15 and 30 feet and moves through the outer atmosphere of the sun. It's not possible to see the comet from Earth, with or without a telescope, NASA said in a Wednesday release. 

"I feel very fortunate to have found SOHO's 4,000th comet," Trygve Prestgard, who first found the comet in SOHO's data, said in a statement. "Although I knew that SOHO was nearing its 4,000th comet discovery, I did not initially think that this sungrazer would be it. It was only after discussing with other SOHO comet hunters, and counting through the most recent sungrazer discoveries, that the idea sunk in."

SOHO, which launched in 1995, is a joint mission between the European Space Agency (ESA) and NASA. It "studies the sun from its interior to its outer atmosphere, with an uninterrupted view from its vantage point between the Sun and Earth, about a million miles from our planet," according to NASA. It's become an effective way to find comets, thanks to its long lifespan and sensitive instruments. Citizen scientists often search through SOHO's data to find new comets.