A rare astronomical phenomenon is about to happen for the first time in 70 years - here's how to watch

AP Photo/J. David Ake

Tonight, the full moon will rise on the same night as the summer solstice, the longest day of the year.

Although mathematical predictions say this event should happen every 15 years, this is the first time it's happening in Universal Time (UT) in nearly 70 years.

And it won't happen again for almost five decades.

This full moon, called the 'strawberry moon' by Native Americans because it marks the start of strawberry season, entered its full phase at 7:02 a.m. ET today.

Today, the sun's path makes its longest, curviest arc across the sky. At 6:34 p.m. ET, 12 hours after the moon becomes its fullest, Earth's northern axis of rotation becomes most tilted toward the sun, marking the summer solstice.

In 1967, the solstice and the full moon were separated by just a few hours but were on different days in some time zones. In US timezones, the last time the summer solstice and full moon mingled was in 1986.

But going with UT, the last time the summer solstice and full moon were truly aligned was in 1948, when the full moon occurred less than an hour after the summer solstice.

This full moon is also rare for another reason, Christian Science Monitor reports. It is the last of four full moons between the March 2016 equinox and the June 2016 solstice. There are usually only three full moons in that period.

Slooh, an online observatory, will be offering a live broadcast of the event. During the broadcast, professional astronomers will discuss the event and take questions from the public.

"Having a full moon land smack on the solstice is a truly rare event," said Astronomer Bob Berman in a Slooh press release. "We probably won't push people off pyramids like the Mayans did, but Slooh will very much celebrate this extraordinary day of light with fascinating factoids and amazing live telescope feeds."

And if you miss it tonight, you won't have another opportunity to experience a Full Moon on the Summer Solstice until June 21, 2062.

Check out the livestream from Slooh tonight at 8 p.m. EST below: