Most SOHO comets come from a single family of fragments linked to a long-ago giant comet, appearing roughly every two days.

NASA estimates that about 95% of SOHO’s comet discoveries come from citizen scientists, with the Sungrazer Project accounting for well over half of all comets catalogued by humanity.

The core insight is that open data access and broad public participation turned a solar-telescope mission into an extraordinary comet-discovery machine, driven by a simple flicking-through-images approach.

SOHO uses the LASCO instrument to create an artificial eclipse, revealing faint material around the Sun and enabling detection of sungrazing comets.

SOHO has outlived its original mission plan; it now takes roughly four to five years to add every thousand comets, and reaching the 5,000th milestone may be its final major landmark as newer instruments assume the solar-watching role.

Launched on December 2, 1995, SOHO was designed to study the Sun, not to find comets, yet it became the most prolific comet finder in history.

The Sungrazer Project, started after launch, lets anyone with internet access download images and report moving specks, lowering barriers to participation.

On March 25, 2024, PhD student Hanjie Tan identified SOHO’s 5,000th comet, highlighting the enduring contribution of citizen scientists who often lack formal training.

The overwhelming majority of discoveries are made by amateur and volunteer citizen scientists using free online SOHO images, not professional astronomers.