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The next full moon will be partially obscured by earth’s shadow for a few hours when the longest “almost total” lunar eclipse in nearly 600 years graces the western skies beginning Thursday night.

Up to 99% of the moon will slip into Earth’s shadow when the event reaches its peak early Friday, at which point the celestial body will appear to turn red, NASA reported.

Provided the night sky is clear, the partial lunar eclipse should be visible to the naked eye. For those dealing with cloudy skies, it can also be watched online here and here.

Stargazers will be able to witness the beginning of the partial lunar eclipse at approximately 11:19 p.m. PST.

Around 12:45 a.m., the moon will start to give off a reddish glow as over 95% of its disk becomes obscured, according to the space agency.

The event hits its peak at 1:03 a.m., and that will be the best time to witness the moon’s red hue.

“The color might be easier to see in binoculars or a telescope,” NASA said on its website. “Using a camera on a tripod with exposures of several seconds will bring out the color, at the expense of overexposing the lit part of the Moon.”

By 1:20 a.m., the moon will no longer appear red, and at 2:47 a.m., the partial eclipse will officially end.

Clocking in at just over 3 hours and 28 minutes, this partial lunar eclipse will be the longest of the century — it will also be the lengthiest since 1440, according to NASA records. Looking toward the future, there won’t be a longer one until 2669.

Weather permitting, the event should be visible in all of North America, plus large parts of South America, Polynesia, eastern Australia and northeastern Asia.

“Partial lunar eclipses might not be quite as spectacular as total lunar eclipses – where the Moon is completely covered in Earth’s shadow – but they occur more frequently,” NASA stated on its website. “And that just means more opportunities to witness little changes in our solar system that sometimes occur right before our eyes.”