After the partial solar eclipse last week, we are now about to get a total lunar eclipse, because eclipses come in pairs. Tomorrow, our natural satellite will cross into the shadow of the Earth, darkening before assuming the characteristic crimson color of this type of eclipse, also known as a "Blood Moon" total lunar eclipse.
Billions of people will be able to see it, weather permitting. People in North America, East Asia, Australia, New Zealand, and across the Pacific Ocean will have a fantastic view of the phenomenon, and it's worth looking out for, there won't be another one for three years.
The event will begin at 8:02 UTC on November 8, with the Moon entering the penumbra of the Earth. Totality will begin over two hours later and it will last about 85 minutes. Unlike total solar eclipses that are over in a matter of minutes, lunar eclipses are a more prolonged affair – and in this one, the Moon will also occult the planet Uranus, coincidentally located along the lunar path in the sky this month.
Why does the Moon turn red during a total lunar eclipse?
The most fascinating fact about total lunar eclipses is that, while in complete shadow, the Moon appears red. The reason for this is the same as why sunsets and sunrises are red: The atmosphere filters and scatters sunlight in a peculiar way, called Rayleigh scattering. Blue light is scattered more than red, getting redirected all over the sky, so when the Sun is high in the sky, the sky appears blue. When the Sun is low on the horizon, we get the redder tones typical of dawn and dusk.
Because the Moon doesn’t have any light of its own and is just reflecting the Sun’s light, during a total lunar eclipse that light goes through our atmosphere because Earth is directly in between the Sun and Moon. The atmosphere scatters the shorter blue wavelengths of light so much they are removed from the sunlight hitting the Moon, just leaving the longer red ones that passed through our atmosphere.
If the sky above you is cloudy or you’re not where the eclipse is visible, worry not. You can watch it online thanks to the Virtual Telescope project. Don't miss it, this will be the last total lunar eclipse until March 2025.