Explainer | The longest partial lunar eclipse of the century is happening on Friday. Here’s where to watch it
- People in many parts of the world will be able to see the moon turn blood-red as it crosses into the earth’s shadow for more than 3 hours
- Large parts of the world, including North America, Australia, mainland China and Hong Kong should be able to witness this rare celestial phenomenon
If you look up at a clear sky on Friday, you might be lucky enough to witness a rare celestial event: the longest partial lunar eclipse of the century, where the moon will turn mostly blood red as it slips into earth’s shadow.
What can I expect?
During a lunar eclipse, the earth moves between the sun and the moon, blocking the sunlight that normally reflects off the moon.
A total or full eclipse happens when the sun, moon and earth are in a perfect line, putting the moon completely in the earth’s shadow. In partial eclipses, part of the moon will be visible throughout as they are not perfectly aligned.
In major eclipses, part of the moon turns copper-red, which Hong Kong Space Museum explains is the result of “the Earth’s atmosphere scattering the blue component of sunlight away, leaving the red component which is refracted by the atmosphere and illuminates the moon”. For this reason, a total lunar eclipse is also known as a “blood moon”.
According to Nasa, earth will experience 57 partial lunar eclipses between 2001 to 2100. Friday’s partial eclipse will last three hours and 28 minutes, whereas the shortest eclipse this century – on February 13, 2082, will last for 25 minutes and 30 seconds.
The Hong Kong Observatory said you can safely watch the partial eclipse with your naked eyes without any special equipment.
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When and where can I see it?
Some parts of the world will miss out altogether or have a limited view, including much of Southern and Central Asia, Africa and Europe. Some of the best views will be in North America, where it will start late on Thursday or early on Friday depending on your local time zone.