There’s a Blood Moon on the rise, and people around the world will be able to catch a glimpse of it today, Friday July 27th, 2018, when the Moon ducks into the Earth’s shadow.
Nigeria is going to experience it. 2018 features two lunar eclipses, one in January and the other in July. On Jan. 31, there was a spectacular Super Blue Blood Moon eclipse.
The July 27 Blood Moon will be the longest total lunar eclipse of the 21st century. Both will be total lunar eclipses when the full moon passes through Earth’s shadow.
Lunar eclipses are visible from anywhere on Earth where it is nighttime. However, the duration of the eclipse you see will depend on how close to moonrise or moonset the eclipse starts in your location.
During total lunar eclipses, the moon turns a deep red colour when it enters the depths of Earth’s shadow. So why doesn’t the moon just look like it’s in darkness?
The colour change happens because Earth’s atmosphere acts as both a lens and a scattering medium for the sun’s light. As light passes through any medium, it slows down a bit and bends. So some sunlight gets bent toward the moon’s surface as it passes through Earth’s atmosphere during an eclipse.
If you were standing on the moon, observing the Earth during a lunar eclipse, you’d see a ring of light around the Earth’s edge as it passed in front of the sun. In addition to the bending, air scatters short-wavelength light more than longer-wavelength light.
Colours such as green and blue have shorter wavelengths than red or orange, so they scatter more — and what’s left is the redder end of the spectrum. This will be the second Blood Moon (also known as a lunar eclipse) of the year. And it’ll last a whopping one hour and 43 minutes, making it the longest one this century.
But the eclipse’s impressive length also means that the Moon itself will actually look a little smaller and dimmer than usual. That’s because the Moon will be as far away as it gets from the Earth on its elliptical orbit, making the Moon appear smaller.
But, the Moon also moves more slowly when it’s that far away, according to Frederick Walter, a professor of physics and astronomy at Stony Brook University. That lets it linger for longer in the Earth’s shadow and stretches out the length of the eclipse.
