Look up at the moon on June 20, and you may be witnessing something that has not been seen in decades. That night, depending on your local time zone, the full moon will rise on the same day as the June solstice for the first time since 1948.

For people in the Northern Hemisphere, the June solstice marks the point when Earth’s northern axis is tipped toward the sun, giving us the longest days and shortest nights of the year. At the same time, Earth’s southern axis points away from the sun, signaling the start of the winter season, with shorter days and longer nights.

This year, the June solstice officially kicks off at 6:34 p.m. ET (22:34 UT), the