On the evening of May 15, there will be a total lunar eclipse visible in western Colorado.
The Earth always casts a shadow from the Sun somewhere in space. Depending upon the orientation of the Earth’s orbit to the Moon’s orbit, sometimes the Moon can pass through the shadow of the Earth. That is a lunar eclipse! This typically happens only twice per year. Note that lunar eclipses always happen at full Moon and solar eclipses always happen at new Moon.
This eclipse takes about 5 hours and begins at 7:33 pm MDT when the full Moon enters the edge of the outer shadow of Earth (the penumbra). Note that, for western Colorado, the eclipse starts before moonrise. In addition, your south-east horizon will impact when the Moon becomes visible at your location.
The total eclipse begins when the Moon completely enters the inner shadow of the Earth (the umbra) and extends from 9.30 pm to 10.54 pm. The eclipse ends completely at 12:51 am, May 16.
At the beginning, the shadow on the Moon is not even detectable. However, over time, you will see the shadow become more pronounced as the Moon progresses deeper into the shadow. At a certain point, the Moon will begin to take on a red glow. Just as a sunset on Earth is red, this is the sunlight being scattered by the Earth’s atmosphere on its way to the Moon!
How many of you know what makes a lunar eclipse? Here is a description of how you can demonstrate a lunar eclipse. You can do this inside, but the room needs to be somewhat dark. Have a good flashlight as the Sun. Cut a 12-inch circle (the Earth) and a 3-inch circle (the Moon) out of a piece of cardboard or other solid material.
An assistant will be the Sun. You will hold the Earth and the Moon. Have them point the flashlight at the Earth. The Earth’s shadow will be on the wall. You can walk around the Sun to simulate the Earth’s orbit during the year. Note there is always a shadow somewhere.
Now hold the Moon at arm’s length away from you and away from the Sun. Slowly move the Moon in its orbit around the Earth into the shadow. Continue to move the Moon until it passes out of the shadow. You just made a lunar eclipse!
Western Slope Skies is produced by members of the Black Canyon Astronomical Society and KVNF Community Radio. This episode was written and recorded by Bryan Cashion.
REFERENCES
Here is a link to a site for eclipses. This link will show a simulation of the lunar eclipse for Montrose. The times should be reasonably accurate for anywhere in western Colorado. Note that all times are in local time zone, even when UTC is stated in the first sentence. For precise times, you can change the location by clicking the “Search for a city or place” in the upper right corner.
All lunar eclipses in 2020s. The next lunar eclipse visible in western Colorado is on the morning of Nov 8, 2022.