Watch the moon set behind mountains on Mount Whitney, in California, during the eclipse on March 13, 2018.
A truly global spectacle is set to unfold Thursday, with the moon set to slide behind the Earth’s shadow across a swath of the planet. The longest total lunar eclipse of the 21st century — this one lasts more than four hours — is set to set in just before dawn on Friday morning.
“This eclipse is special not only because it is the longest totality but also because of the widespread spread of darkness over a large chunk of the Earth,” NASA said in an alert issued Wednesday. That the eclipse appears to last more than four hours — unusually long, according to astronomers — makes it a spectacle for everyone.
The total lunar eclipse will occur on Thursday evening (Eastern Standard Time), and begin to be visible a couple of hours later. Those interested can watch at noontime on Friday. As expected, the moon will set behind the dark portion of the Earth’s shadow, beginning at 6:14 p.m. EST.
The Earth’s natural satellite will cast a huge shadow — an umbra, or dark shadow — over its surface beginning at 10:11 p.m. EST on Thursday. The shadow will spread around the planet until it reaches totality at 1:48 a.m. EST on Friday morning.
The moon will appear only partially eclipsed during this event — about 99 percent, to be exact — and the deepest stretch of darkness will come at approximately 1:37 a.m. EDT.
This is the first of two lunar eclipses that will affect the world this year. The second will begin a little after 9 p.m. EST on April 14. In both events, the shadow that will cover the moon, known as a penumbra, will be visible in parts of Asia and some parts of Europe.