Get ready for a glorious Harvest Blood Moon on 7 September

My feelings about the moon changed in the past year, when I gave birth on the day of not just a full moon, but a Harvest Moon.

For the first few months of my son’s life, the passing of time felt very strange – there was little distinction between day and night. But the moon’s almost-monthly cycle was there to remind me that the months were ticking on. Every time I saw a full moon, I knew another 29.5 days had passed by. It was a reminder that my son was around another month older.

It is now almost a year later, and the next full moon is going to be particularly special. On 7 September 2025, there will be a total lunar eclipse.

It will be visible to people in most of Europe, Asia, Africa and Australia, and parts of South America, too. From where I live, in the UK, the eclipse will begin when the moon is below the horizon, but about 20 minutes later, around 7:30pm, it will become visible and will stay that way until the eclipse finishes.

As I said, the moon orbits Earth every 29.5 days. During a full moon, our planet sits between the moon and the sun, so that the entirety of the moon’s face reflects light back towards Earth.

But because the moon’s orbit is slightly tilted compared with Earth’s around the sun, the three bodies don’t line up in one plane – a phenomenon known as syzygy – during every orbit.

When syzygy happens during a new moon, we get a solar eclipse. When syzygy occurs during a full moon, there is a total lunar eclipse.

When this happens, the moon moves into a shadow cast by Earth. This is why the moon is always visible during a lunar eclipse – it just appears darker and redder. The only light that still reaches the surface of the moon and is reflected back at us has passed through Earth’s atmosphere, which scatters most of the wavelengths of light except the red ones.

To work out when to see the eclipse, and how much of it will be visible from where you live, you can use interactive eclipse maps. These will give you the best idea of how to view it.

Unlike a solar eclipse, you don’t need any special protective equipment to view a lunar eclipse – just a clear sky. Once you know when to look, find the moon and watch it darken and redden (pictured). You might want to see how it looks through some binoculars. If you live in the UK, the moon will be low in the eastern horizon that night, so you will need to find a spot with a clear view to the east.

This specific event is known as a Harvest Blood Moon – “Harvest” because it is the full moon that occurs right before the autumn equinox, and “Blood” because of the moon’s red colour during an eclipse.

I am not sure if he is old enough to appreciate it yet, but I will be taking my son, born on a Harvest Moon, out to show him the total eclipse.

Abigail Beall is a features editor at New Scientist and author of The Art of Urban Astronomy. Follow her @abbybeall

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