Besides light, the Sun sends out particles in the form of solar wind and in large bursts called coronal mass ejections. Understanding how these streams and bursts of particles get pushed out from the Sun could help improve our forecasts of space weather reaching Earth.
Recently, the European Space Agency’s Proba-3 mission demonstrated that it filled the ‘solar observation gap’. It can see movement to unprecedented detail in the hard-to-observe region between the Sun’s surface and higher up in its outer atmosphere (the corona). This makes it possible to closely track solar wind as it sets off from the inner corona.
The (artificially coloured) yellow part of the video shows the Sun in ultraviolet light, recorded by the SWAP telescope on ESA’s Proba-2 spacecraft. The greyscale area around it is based on data captured in visible light by the ASPIICS coronagraph on Proba-3. This data is processed to enhance contrast.
You can see flows of solar wind moving away from the Sun in all directions. In some regions, particularly around the bottom of the video, you can see some material also falling back towards the Sun. In the second half of the video, a coronal mass ejection expands towards the right.
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[Video description: A square video with the Sun in the centre, glowing yellow and covered with a mix of darker regions and bright, yellow arcs extending from the surface. Around it, a speckly white-grey-black video showing streams of material moving outwards along rays extending from the Sun. On the bottom, some material moves inwards, and a large burst of material expands to the right from the Sun’s right side, in a series of arcs shaped like backwards Cs.]
[Technical details: Proba-2/SWAP data is measured at a wavelength of 17.4 nm with a cadence of 2–4 minutes and shown to 1.2 solar radii from the Sun’s centre. Off-limb intensity was increased with a radial filter to highlight structures up to the edge of the field of view. Proba-3/ASPIICS data is recorded in visible light with a cadence of 30 seconds and shown from 1.2–3.0 solar radii from the Sun’s centre. ASPIICS data is contrast-enhanced using image stacking, a radial filter, highlighting the dynamics via a running difference, and applying the WOW (wavelet-optimised whitening) algorithm.]