Although lunar eclipses are far more common and easier to catch than solar eclipses, that makes them no less special. And, on the night of September 27th, we get another opportunity to see one of these spectacles. However, this time around we get something special – its also the same evening that we get a supermoon. This makes the event special in that it only happens only once in every thirty years or so. What makes this so special? What is a supermoon? Will it make superheroes finally gain their powers? Read on, and learn…
First, let’s explore what a lunar eclipse is and how it happens. The moon travels around the Earth once every 27.3 days, and its rotation period is the same, so we always see the same face pointed toward us. Each night, we see a piece of the moon that is getting sunlight, until it’s between us as the sun, when we get the New Moon. This is typically when we have a chance of a solar eclipse. On the other side of this, we have the full moon when the moon is on the side of the Earth opposite the sun. An eclipse can happen at this phase, if the moon is positioned so it can pass through the shadow cast by the Earth. So, what does the moon being a “supermoon” mean?
Not as well known is the fact that the moon’s orbit is not circular, but rather an ellipse. And furthermore, the moon doesn’t orbit the Earth, but rather they both circle around the gravitational point that the two bodies have with each other, called the barycenter. This point is inside the Earth, so it looks like it orbits us. This results in the orbit of the moon being elliptical, and allows the moon to move closer to us from time to time. This is called its perigee. When the moon is closest at the same time the full moon phase happens, we get a “supermoon.” The moon will be 14% larger in the sky as well around 30% brighter. Should make for quite the show. This intersection of the full moon event and the supermoon event happens only once every thirty years, so this should be something everyone should take a moment to see (weather permitting!).
What should we expect? Well, around 9pm Eastern time the moon will start to move into the Earth shadow, making it look like something has covered part of the moon’s disk. This part is called a “partial eclipse.” Over the next hour and a half, the shadow will grow in size and eventually, it will completely cover the moon, reaching “totality” around 10:45pm Eastern. At this point it will turn red as the sun’s rays are refracted through the atmosphere around the edges of Earth and the red light waves shine on the moon’s face. The moon is now basking in “Earth shine,” as it is receiving no direct light from the sun. Imagine how this event must have looked to ancient man when they looked up and saw our constant companion turn the color of blood in the night sky.
After 11pm, it should start to recede, the red color fading and the moon starting to reappear as normal as it continues through our shadow and out the other side. After 12:30am on the east coast, the event should be mostly over and the moon will look normal again.
So while this is a normally benign and commonplace event in our night skies, it’s still a wonder to see and reminds us all that even here on the ground on Earth we can see the majesty and wonder that exists in our local solar system. This is a great opportunity to have children witness the wonders of our universe, and can be used as a stepping stone to introducing them to other great things that exist out there, deep in space. Sure, it’s later than many of their bedtimes, but the learning experience should outweigh any missed sleep.
Sorry, I doubt any new superheroes will be born because of a lunar eclipse. But hey, that show starts up on September 24th at 8pm, but that’s not in the scope of SpaceCrazed.
Happy Star Gazing!