Sun-kissed

THE SUN, MILKY WAY

Gliding between two enormous sunspots, the International Space Station looks little more than a toy.

The ISS passed across the face of the Sun on 5 September 2017, captured here by Dani Caxete in Madrid. ISS transits aren’t as rare an occurrence as you might think (you can find out the next one near you on transit-finder.com), but the photographer – shortlisted in the Insight Investment Astronomy Photographer of the Year 2018 – had to be quick: the ISS took less than a second to whizz across the solar disc.

The sunspot regions on either side of the ISS – called AR 12674 (on the left) and AR 12673 (on the right) – flared up in September 2017, and are each composed of around 30 individual spots. Sunspots are cooler regions on the Sun’s surface that form where the Sun’s magnetic field is particularly strong, which inhibits the convection of heat to the surface. The two outbreaks shown here each cover an area of over two billion square kilometres – that’s four times the surface area of the Earth.