Comet Tsuchinshan-ATLAS photobombs SOHO spacecraft during powerful solar flare

Nothing makes a photo more interesting than an unexpected guest appearing in the background. And how cool would it be if the photobomber were a comet?

That's exactly what happened to the sun-studying Solar and Heliospheric Observatory (SOHO) spacecraft, a joint effort of the European Space Agency (ESA) and NASA, beginning on Oct. 7.

Typically, scientists use the view from SOHO's Large Angle Spectrometric Coronagraph (LASCO) instrument to monitor the sun's activity and determine if a coronal mass ejection (CME) accompanies a solar flare from active sunspot regions. Coronographs block the overwhelmingly bright solar disk from view, allowing scientists to get a better look at solar activity that would otherwise be hidden by the sun's glare.

This week, a thick, bright line entered from the right side of SOHO's imagery and paraded across the field of view, moving toward the top of the frame. This vibrant white object was confirmed to be Comet C/2023 A3 (Tsuchinshan-ATLAS).