See The June Strawberry Minimoon Tonight

The Full Moon rises over paper birch trees lining a shore of Boulder Lake north of Duluth last month. Tonight, it will be full again and appear smaller than usual. Credit: Bob King

Half a moon cycle ago, I wrote about the crescent supermoon making its appearance in the evening sky. Supermoons occur around the time of new and full moon, when the moon is at or near perigee, its closest point to Earth. The reason the moon’s distance varies throughout its cycle is because it orbits the Earth in an ellipse, a shape that resembles a squashed circle. One end of the ellipse is closer to our planet, the other farther. The farthest point is called apogee.

The moon’s orbit around Earth is an ellipse with one end closer to the planet (perigee) and the other farther (apogee). A supermoon occurs when the full moon is close to perigee; a minimoon when at apogee. Not to scale. Credit: NASA

Since perigee and apogee are directly opposite one another, and the moon reached perigee around new moon, guess what’s happening tonight at full moon? Apogee! At apogee, the moon is most distant and noticeably smaller compared to average. That’s why it’s also known as a minimoon.

The traditional name for the June moon is the Full Strawberry Moon, named for the most popular berry in the world. On a hike last week I saw hundreds of strawberry plants in bloom. I’m hoping they’ll be replaced by luscious red fruit before the next full moon.

For the Americas, the moon will appear full tonight (June 8) and tomorrow night. That’s because the moment of full moon occurs at 8:09 a.m. CDT. So, if you go out tonight, you’ll see the moon about 12 hours before full, and if you look again tomorrow night, it will be about 12 hours past full. Will you be able to see that it’s slightly out of round both nights?

The moon’s size from perigee to apogee varies by 14%. When the two different-sized moons are overlapped, the difference is very obvious. Credit: Fred Espenak

The moon reaches perigee today at 5:22 p.m. CDT (22:22 UT) just hours before full, when it will be 252,526 miles (406,401 km) from the Earth. That’s 13,626 miles (21,928 km) or 1.7 Earth-diameter farther away than its average distance. At least a few keen-eyed observers can accurately remember the size of the moon and notice the difference between a supermoon and minimoon. The rest of us need some help.

My Supermoon Sighter can also become a Minimoon Sighter. For directions on making one, click here. The basic idea is to see which slot the tonight’s minimoon fits best then compare to the next supermoon. Credit: Bob King

Last November, we had one of the biggest supermoons ever. I suggested then that you make your own Supermoon Sighter to compare the size of the supermoon to this month’s minimoon. If you still have the Sighter, dig it out and make your comparison tonight. If you haven’t made one, you can now and then compare tonight’s full moon to the next supermoon on Jan. 2, 2018.

For those who love full moon moonrises and strawberries, and who doesn’t, click here to find the time for your town when the big strawberry crests the southeastern horizon.