Stargazing in June: The Sun turns dangerous

It’s all eyes on the sky on the morning of 10 June – but with protective gear in place. Not face masks and PPE this time, but special “eclipse glasses” to prevent the Sun’s heat from frying your eyeballs. Yes, we’re being treated to a solar eclipse.

Because the Moon is close to the Earth at the time, it appears too small to completely cover the Sun’s shining face, so no-one is going to see the splendour of a total eclipse of the Sun. But if you’re in the right place – a narrow swathe of the Earth’s surface stretching from northern Canada through the North Pole to eastern Siberia – you will experience the unusual sight of an annular eclipse, with a narrow ring of the Sun’s disc visible around the Moon’s silhouette.

A much larger region of the northern hemisphere will witness a partial eclipse of the Sun. It’s the first solar eclipse of any kind visible in the UK for four years, so make sure you can get out and observe the sight if you can.

From London, the Moon starts to encroach on the Sun at 10.08 am, and the eclipse ends at 12.22 pm. Midway through, at 11.13 am, the Moon covers 32 per cent of the Sun’s face. The extent of the eclipse, and the timings, vary according to your location. The best view is from Shetland, where 50 per cent of the Sun lies behind the Moon at 11.27am. (Check out the details for your location at timeanddate.com)

This eclipse is a curtain-raiser for a decade of increasing excitement centred on our local star. As well as supplying a steady stream of light and heat, the Sun suffers spasmodic eruptions that reverberate around the Solar System, and have the potential to inflict serious damage on the infrastructure we depend on. In 1859, a huge magnetic storm on the Sun induced electric currents in the telegraph system that electrocuted some of the operators. A similar storm today could destroy electricity grids and mobile phone networks, and potentially shut down power stations and military installations – causing international mayhem on the scale of a pandemic.

The Sun’s magnetic activity waxes and wanes over an 11-year cycle. After reaching a minimum in December 2019, our star is now starting to flex its magnetic muscles again, with the crescendo expected around 2025.

And outbursts from the Sun are even more dangerous to astronauts than to those of us protected under the Earth’s double protective umbrella, of its magnetic field and its atmosphere. Unfortunately, the forthcoming peak of solar activity coincides with Nasa’s planned date to return astronauts to the Moon, with its Artemis programme.

Once underway, space-farers have no protection from the lethal onslaught wreaked by an eruption on the Sun. Nasa got away with it once. A brutal solar storm erupted in August 1972, between the lunar missions Apollo 16 and 17. If an astronaut had been caught Moon walking, they would have suffered a potentially lethal dose of radiation.

Back in the 1970s, there was no way of predicting the Sun’s outbursts. Now, we have a flotilla of spacecraft monitoring solar weather, to help us foretell what the Sun about to do. Spearheading the investigation are two audacious missions. The European Solar Orbiter is currently edging in towards the Sun, and will settle itself into a tilted orbit where has a close-up 3D view of our local star.

Even more audacious is Nasa’s Parker Solar Probe. Its orbit is taking it ever closer to the solar surface, so that by 2025 it will be skimming just 6 million kilometres above the Sun’s superheated gases. The searing heat will broil the front of Parker to 1400 C – hotter than the lava erupting from a volcano.

The pay-off is that by probing the Sun from such close range, scientists hope to understand the secrets of the Sun’s erratic magnetic weather, and predict its most lethal storms.

What’s up

As the Moon passes between the Sun and the Earth on 10 June, it treats us to a solar eclipse (see main story). Moving into the evening sky, the thin crescent Moon forms a lovely pairing with Venus on 12 June. The brilliant Evening Star hangs low in the north-west all month, shining brighter than anything else in the night sky, bar the Moon.

To the upper left of Venus, you’ll find an apparent line of three stars. The pair to the right are Castor and Pollux, the celestial twins heading up the constellation Gemini. The interloper to the left is the planet Mars. Look out for the crescent Moon skimming just above the Red Planet on 13 June.

Roll on 23 June, and Mars passes right in front of the star cluster Praesepe (in Cancer), fondly known as the Beehive Cluster. Through binoculars or a small telescope, enjoy the sight of the Red Planet being buzzed by a swarm of faint stars!

The bright star high in the south is Arcturus, the leading light of the kite-shaped constellation Boötes (the Herdsman). The star’s name means the “bear-warden”, because it seems to herd the Great Bear (Ursa Major) round the sky as the Earth rotates. The celestial bear’s seven brightest stars form the familiar shape of the Plough, which lies almost overhead these summer nights.

And, if you’re up after midnight, look out for the two giants of the Solar System – Jupiter and rather fainter Saturn – rising in the southeast.

Diary

10 June, 11.52 am: New Moon, eclipse of the Sun

12 June: Crescent Moon near Venus

13 June: Crescent Moon near Mars

15 June: Moon near Regulus

18 June, 4.54 am: First Quarter Moon

19 June: Moon near Spica

21 June, 4.32 am: Summer solstice

22 June: Moon near Antares; Venus near Castor and Pollux

23 June: Mars in front of Praesepe

24 June, 7.39 pm: Full Moon

27 June: Moon near Saturn

29 June: Moon near Jupiter

Philip’s 2021 Stargazing (Philip’s £6.99) by Heather Couper and Nigel Henbest reveals everything that’s going on in the sky this year