It was almost a year ago that parts of the world were enveloped in darkness caused by a total solar eclipse, whose path of totality journeyed all the way from South America to the east coast of the USA.
However, it’s not the only kind of eclipse we witness on this brilliant planet, and a partial lunar eclipse, also known as a blood moon, is on the celestial calendar for next week. So, if you’ve ever wondered why the moon occasionally takes on an eerie red glow, and even more importantly, how you can catch a glimpse of it, read on for everything you need to know.
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What is a blood moon?
A blood moon occurs because of a lunar eclipse, when the earth comes directly between the sun and the moon, blocking all direct sunlight (this patch of darkness is called the earth’s umbra). However, the moon takes on a spooky reddish hue because some sunlight still reaches it indirectly, via the earth’s atmosphere.
So, why red? Well, as the sun’s rays pass through the earth’s atmosphere, some colours in the light spectrum (towards the violet end of the spectrum) are filtered out. This phenomenon is called Rayleigh scattering, and it’s the same thing that creates those gloriously colourful sunrises and sunsets. Red wavelengths are affected by scattering the least, and it’s that light which reaches the moon’s surface.
When is the blood moon?
The next blood moon will take place on March 13-14, lasting for around 65 minutes. It will be most visible in North and South America, particularly on the west coast as the skies tend to be clearer there at this time of year. Those of us in east Asia and Australia might catch parts of the moonrise, and in western Europe, people might be able to see parts of the moonset. And, it goes without saying, but the best views will be had in areas which are free of light pollution.
The eclipse happens in five stages. First, the moon will enter the penumbra (outer shadow) of the earth, before losing its brightness. That’s when a reddish shadow will begin to spread across the moon, as the earth moves across the sun’s path. The eclipse will reach totality around halfway through those 65 minutes, meaning it will look completely red. Afterwards, the moon’s red glow will begin to fade into its usual bright glow, according to Discover Magazine.
To check what time the blood moon will be visible near you, have a look on TimeAndDate.com. A total lunar eclipse will be taking place on September 7, and another partial one will be almost a year later, on August 28, 2026.
While we’re on the subject, have a look at our deep-dive into noctourism, and why dark sky travel is going to be huge this year.
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