The longest total lunar eclipse of the 21st century takes place this Friday, July 27.
The total phase of the “blood moon” eclipse of July 27 will last 1 hour and 43 minutes, during which Earth’s natural satellite will turn a spectacular red or ruddy-brown color. From start to finish, the entire celestial event will last nearly 4 hours.
The eclipse won’t be visible to viewers in North America, except via webcasts. But observers in much of Africa, the Middle East, southern Asia and the Indian Ocean region will get an eyeful, given the cooperative weather, according to lunar scientist Noah Petro, of NASA’s Goddard Space Flight Center in Greenbelt, Maryland. [In Photos: The Rare Super Blue Blood Moon Eclipse of 2018]
July’s total lunar eclipse occurs on the same day the planet Mars reaches its opposition when it will shine at its best in the night sky. This month, Mars will be at its closest to Earth since 2003. After opposition, when Mars will be brightest, it will reach that closest point on July 31. You can learn more about that event in our dedicated guide here: Mars at Opposition 2018: How to See It and What to Expect
What is the Blood Moon of July 27?
Unlike with solar eclipses, you need no special equipment to observe lunar eclipses. These latter events, which occur when the moon passes into Earth’s shadow, are safe to view directly with the naked eye, telescopes or binoculars.
The moon turns deep red or reddish brown during eclipses, instead of going completely dark. That’s because some of the sunlight going through Earth’s atmosphere is bent around the edge of our planet and falls onto the moon’s surface. Earth’s air also scatters more shorter-wavelength light (in colors such as green or blue); what’s left is the longer-wavelength, redder end of the spectrum.