Solar eruption glimpsed by SoloHI

Solar Orbiter’s Heliospheric Imager (SoloHI) captured this coronal mass ejection emanating from the Sun on 12 February 2021.

This black-and-white movie comprises one 248 x 248 pixel detector tile of the larger four-tile detector, and therefore only part of the CME is seen. Furthermore, the images were captured at a lower than normal telemetry rate of one image every two hours.

SoloHI takes images of the solar wind – the stream of charged particles constantly released by the Sun into outer space – by capturing the light scattered by electrons in the wind. The image reveals the K corona, which is light from the Sun reflected off of electrons. It is very faint – in fact, 99% of the light in the image needs to be removed before you can see it. Most of that removed light comes from the F corona, which is light reflecting off of dust near the Sun.

The ‘missing’ spot in the image on the far right is an overexposed area where light from another instrument is reflecting into SoloHI’s view. The little black and white boxes that blip into view are telemetry blocks – an artifact from compressing the image and sending it back down to Earth.