A total solar eclipse is a rare phenomenon. Tomorrow, the sky will be plunged into darkness across Britain, Ireland, Greenland, Spain and Iceland. In the UK, the spectacular event will kick off after 6pm. Eclipses happen when the Moon passes between the Earth and the Sun. But a cosmic coincidence means that during eclipses on Earth, the Moon fits perfectly over the Sun, like a puzzle piece slotting into place.

This is because the Sun is around 400 times wider than the Moon, but also about 400 times further away. This means they appear about the same size in our sky. On other planets, moons either don’t completely cover the Sun, or they appear much larger. In the latter case, they lack the satisfying alignment we see on Earth, where the Moon and Sun almost match each other in size.

The eclipse will offer the briefest of respites from the blazing summer sun. Canals can help offset this seasonal heat by cooling city neighbourhoods up to 50 metres from their banks, new research shows. Even small drops in temperature can benefit people’s health and wellbeing. But this summer has also seen a severe drought grip the UK, with important knock-on effects for food security.

The courtiers who surrounded Queen Elizabeth I had to deal with a different kid of heat. The fiery monarch wrote furious letters to those who disobeyed or disappointed her. However, a detailed analysis of the missives shows that the Queen strategically deployed emotion to achieve her political goal