Driftless Dark Skies: Two Full Moons in a Month

January 4th, 2018 by John Heasley

January opens with the Full Wolf Moon and ends with a Total Lunar Eclipse. It is unusual to enjoy two Full Moons in the same month, but it can happen because the time between Full Moons is 29 ½ days. That means no Full Moons for February but two for March. There is no official definition, but folks sometimes like to call the second Full Moon of the month a Blue Moon. But January’s second Full Moon will be more orange or red than blue.

Watch for the Full Moon rising on January 1 in the ENE around 4:35pm in the Driftless. The Ho-Chunk Nation, who lave long called this area home, call this Hųjwičonįną or First Bear Moon. A fun way to predict where it will rise is to turn your back to the Sun before it sets in the WSW at 4:36pm and just follow your shadow. Full Moon is a moment of syzygy when Sun, Earth, and Moon are aligned. The Moon is 100% full at 8:25pm, and you can see it surrounded by the bright stars of the Winter Hexagon with Orion to the right. This Moon is sometimes called a Supermoon. The Moon is a little closer to Earth and appears 7% larger than normal. The size difference is not always noticeable, but the Full Moon rising is awesome.

On January 31 (29 ½ days later), the Full Snow Moon will be darkened as it passes through the shadow of the Earth. You will need to get up early and find a spot with a clear view of the western horizon. Just choose one of our many ridgetops. The eclipse begins at 5:48am as the upper left part of the Moon begins to darken. Binoculars will help you enjoy more of the details and watch the shadow of the Earth move across the plains and mountains and craters of the Moon. While you have them out, slew just to the right of the Moon to be awed by the Pleiades star cluster. The Moon is completely in Earth’s shadow at 6:51am and reaches maximum eclipse at 7:13am. By then it appear orange or red. The Moon sets around7:20am in the WNW just after the Sun rises at 7:18am. Watch again as your shadow from the rising Sun points toward the setting Moon. You should be able to see both at once and find yourself balanced between Sun and Moon on Earth. Pour yourself a warm beverage to celebrate being syzygied and look forward to the next Total Lunar Eclipses visible over the Driftless on January 20, 2019 and a tetrad of four in 2021 and 2022!

John Heasley is an astronomy educator and stargazer who enjoys connecting people with the cosmos. He volunteers with NASA/JPL as a Solar System Ambassador. For more information about stargazing in southwest WI, like Driftless Stargazing LLC on Facebook and find out whenever there’s something awesome happening in the skies. Driftless Dark Skies appears monthly in the Voice of the River Valley.