06/09/2025
Our Sunday night guests are in for a treat 🤩
Don't miss the rare total lunar eclipse this Sunday evening (7 September), also known as the “blood moon”!
Our planet's natural satellite will appear a distinct dark red colour. Let's break down why this happens 👇
The Earth will pass directly between the sun and the Moon, casting its shadow on the Moon. ☀️🌍🌕
This will be the first total lunar eclipse visible from the UK since 2022, and the only one until 2028—so it’s a real treat.
But why is it red? 🩸
During a total lunar eclipse, sunlight passes through Earth’s atmosphere, scattering more of the shorter blue wavelength light, allowing the longer red wavelength light to remain visible.
It’s the same reason sunsets are red 🌇 Only this time, the Moon is catching the glow.
This is also known as Rayleigh scattering.
This phenomenon was first conjectured by John Tyndall, whose work on light laid the groundwork for Lord Rayleigh’s later formal theory.
Both men worked here at the Royal Institution and helped explain the colour of the sky. 🩵
The total eclipse will start at 19:11, but unfortunately it will be below the horizon in the UK. Those who are lucky to have clear sightlines of the horizon may catch the end of totality which will end at 19:52.
However, as the Moon rises higher in the sky, you may see the Moon get less red and get brighter as it starts to come out of the Earth's shadow as the night goes on. These times are for London and you can check timeanddate.com for your specific location times
The Met Office recommends being somewhere with a clear view of the eastern horizon.
Unlike solar eclipses, you don't need protective goggles to view this one.
If you like observing and understanding our universe, you'll love the 2025 Christmas Lectures with space scientist Dame Maggie Aderin-Pocock!
Dame Maggie will take us on a journey far away from our planet, exploring the fascinating science of outer space. https://www.rigb.org/christmas-lectures
