A Solstice to Remember: Solar Observing at the Royal Observatory, Sunday 21 June 2026

There are few better ways to celebrate the longest day of the year than by pointing our telescopes at the very star responsible for it. On Sunday 21 June 2026, the summer solstice, volunteers from the Flamsteed Astronomy Society gathered at the Royal Observatory Greenwich for a morning of solar observing, and the Sun rewarded us with a real treat.

We had glorious weather from the outset. It was a hot day with clear blue skies for most of the session, the sort of weather that brings the crowds out onto the hill, and out they came. Between 10:30am and 1pm, around 200 visitors stopped by to take a safe look at our nearest star.

As always, the morning began with the familiar routine of carrying the equipment up from the stores and setting everything up ready for our first visitors. Once we were up and running, there was plenty to see.

The session gets underway. Pictures by Mike Meynell.

The Sun put on a fine show. Through the white-light filters, visitors could make out several sunspots peppered across the solar disc, always a favourite with the public once they learn that some of those spots are larger than the Earth itself. Over on the hydrogen-alpha telescopes, the view shifted to the fiery edge of the Sun, where prominences could be seen looping and arching off the limb in beautiful detail.

The Sunspotter showing some small sunspots. Picture by Mike Meynell.

Then came the surprise that had many of us looking up rather than down the eyepiece. High in the sky, a halo appeared around the Sun, a complete ring of light encircling it. This is what is known as a 22-degree halo, caused by sunlight passing through countless tiny ice crystals in high, wispy cirrus cloud. The crystals bend the light rather like a lens, throwing a ring around the Sun. On such a hot, bright day, it was a lovely reminder that there is always something going on in the sky above us, not just through the telescope. Prominences leaping off the Sun and a shimmering halo surrounding it, all on the solstice, made for a truly memorable combination.

For the second event in a row, a solar halo appears. Picture by Mike Meynell.

After two and a half hours of sharing the Sun with around 200 delighted visitors, it was time to pack everything away and return it to the stores.

Most of the Flamsteed team for the day: Richard, Frederik, Tim, Paul, Alec, Miyuki, Manish, Helen and Clive. Not pictured is Mike Meynell, who took the picture!

It only remains to say a huge thank you to all the volunteers who gave up their solstice morning to make the session such a success, and to everyone who came along and looked up with us. The longest day, the Sun at its highest, sunspots, prominences and a halo to finish it all off. We could hardly have asked for more.