March Madness Means Two Full Moons

Two people watch the Full Worm Moon rise Thursday evening from a mound of ice on Lake Superior in Duluth on March 1. Bob KIng

There are two full moons this month. One on March 1 called the Worm Moon and a second or Blue Moon on March 31. You’ll recall that January also had two full moons and February none.  Full-moon-less Februaries are rare, occurring only 4 times a century according to Sky and Telescope’s Roger Sinnott. Even rarer? A leap year February without a full moon. That last happened in 1608 and won’t happen again until 2572.

If you missed last night’s, it will be nearly full tonight (Friday) and rise in a much darker sky. Click here to find find the time of moonrise for your location.

It didn’t take 10 minutes for the moon to pull itself up from the horizon and shine brightly against the gray-blue band of Earth’s shadow. Bob King

I went down to the beach here in Duluth to watch moonrise and found a few souls wandering out on the frozen ice shelf that extends several hundred feet from the shore. Soon, we were all caught up in that big, orange globe. A full moon-rise is a most colorful affair. Not only does the moon continuously change color from deep pink-orange to bright yellow, but the eastern sky glows with the dusky purples and pinks of Earth’s rising shadow.

Full moon is the best time to see the bright, fresh crater Tycho and its magnificent ray system that stretches across more than 1,200 miles (2,000 km) across the lunar surface. Crater and rays were formed when a 5-6 mile (8-10 km) wide asteroid struck the moon 108 million years ago, the time of the Cretaceous Period on Earth, when dinosaurs thudded through the pine trees. Not only would they have witnessed the impact, visible as a bright flash of light, but it’s possible that some of the rock blasted from the crater eventually found its way back to Earth and landed as lunar meteorites.

Tycho stands out brilliantly at full moon (the “belly button” with bright streaks just up from the bottom or southern limb of the moon) because it’s fresh compared to other large craters, which are typically 3.9 billion years old. Tycho is 53 miles (86 km) across. Frank Barrett /

Fragments from the impact rained down on the lunar landscape to create countless secondary craters, which dug up bright-toned, unweathered material from below. Tycho’s bright, too for the same reason.  Both it and the rays will eventually darken and blend into the landscape in the distant future because of space weathering. Solar flares, cosmic rays and micrometeorites work in consort to darken and grind down the rays.

Binoculars will show easily show Tycho and the full extent of its rays. Look for it about a quarter the way in from the lower of the moon. Although both crater and ray system are visible near moonrise, you’ll get a crisper view a half to hour later. For more about Tycho, please see my recent Sky & Telescope blog.

2 Responses

  1. kevan Hubbard

    Yes Tycho is impressive. The ice on the lake Duluth is on looks impressive too,superior, Michigan? Can’t remember which? Looks like you could walk across to Canada, well not if it’s Michigan!

    1. astrobob

      Hi Kevan,

      From downtown looking out the lake ice seems to go on and on but it ends somewhere between the edge of Duluth and the next nearest town — maybe 5-6 miles worth?

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