lunar eclipse

Eclipse-Mania!

The October 8, 2014 total lunar eclipse.

The October 8, 2014 total lunar eclipse.

By Jim Haklar

I love eclipses. I mean, I really love eclipses! I love eclipses so much that two years ago, I flew to Albuquerque for the weekend to see a solar eclipse. But more about that later…

An eclipse happens when the Earth, Moon and Sun all line up. Technically, this is called syzygy (try to form that word in a game of Scrabble). A lunar eclipse happens when the earth is between the Moon and the Sun. When the Moon is between the Sun and the Earth you get a solar eclipse. Lunar eclipses happen when the Moon is full and solar eclipses occur when the Moon is new. So, why don’t we have an eclipse twice a month? Well, the Moon’s orbit is tilted by a little over five degrees. So most of the time there isn’t perfect alignment and you don’t have syzygy.

From any given location on the Earth, lunar eclipses are more frequently seen than solar eclipses. That’s because the Earth casts a bigger shadow on the Moon than the Moon does on the Earth. The shadows consist of two parts. There is a smaller, darker umbra surrounded by the lighter penumbra. If you are in a location where the Moon’s umbra passes through, you will see a total solar eclipse. Otherwise the solar eclipse will be partial (since you will be in the penumbra). For lunar eclipses, the situation is a little different. The Moon can completely or partially pass through the Earth’s umbra (resulting in a total or partial lunar eclipse) or just pass though the penumbra (called a penumbral eclipse).

Now for my Albuquerque story. Two years ago the Moon’s umbra passed directly in front of the Sun and this was visible in many cities including Albuquerque (I went to Albuquerque because of the clear weather). But since the Moon was at a point in its orbit when it was farther away from the Earth, it didn’t completely block out the Sun. Instead, an annulus or ring of light from the Sun’s disk encircled the Moon. This is called an annular solar eclipse.

On August 21, 2017 there will be the first a total solar eclipse visible from the contiguous United States in over 30 years. Information on the best places to see the eclipse is already on the Web, so start think about taking an eclipse vacation!

About the Author: Jim is an environmental engineer at the EPA’s Edison, New Jersey Environmental Center. In his 28 years with the agency he has worked in a variety of programs including Superfund, Water Management, Public Affairs, and Toxic Substances. He has been an amateur astronomer since he was a teenager, and can often be found after work in the back of the Edison facility with his telescope.

Editor's Note: The opinions expressed here are those of the author. They do not reflect EPA policy, endorsement, or action, and EPA does not verify the accuracy or science of the contents of the blog.

Please share this post. However, please don't change the title or the content. If you do make changes, don't attribute the edited title or content to EPA or the author.

Science Wednesday: Season’s Greetings for the Eclipse

Each week we write about the science behind environmental protection. Previous Science Wednesdays.

By Aaron Ferster

While yesterday was the solstice and the “official” start of winter, it’s been feeling like the season got an early start around the Washington, DC area this year. It’s been cold.

I don’t think it got much above 25 degree the night before last in my neighborhood. So naturally, sometime just before 2:00 a.m., my wife and I roused our two daughters out from beneath their covers and marched them outside into the frigid night air.

Time to watch the moon disappear.

No one complained. We watched wide-awake as the stunning bright yellow of a giant full moon slowly gave way. First just a small slice of the Cheshire-cat-like moon slipped away. Then, as the sliver of darkness advanced, a brownish red hue spread across what was left of the moon. A holiday light show in the night sky. Slowly and steadily, light gave way to shadow.

As we stood outside all bundled up, we chatted about the spectacle that was unfolding, and how long it’s been since there was a full lunar eclipse this close to the winter solstice. (1638 was the last time, according to an expert cited in The Washington Post.)

There were more than a few bleary-eyed people on the train platform the next morning, and my daughter reports that nearly every kid in her class rose their hand when the teacher asked who woke up to watch the moon disappear.

There is something universally appealing about watching such a natural spectacle. I like to believe that the lunar eclipse is, in essence, a science story. It was another opportunity to get outside and note how science and the environment unite us by peaking our interest and giving us a common story to share with our kids, neighbors, and coworkers.

Were you one of the many people watching the lunar eclipse the other night? What other science and environmental stories do you think you’ll remember from 2010?

Share your experiences and thoughts in the comments below.

And happy holidays!

About the author: A dedicated night-owl, Aaron Ferster is the lead science writer in EPA’s Office of Research and Development and the editor or Science Wednesday.

Editor’s Note: The opinions expressed in Greenversations are those of the author. They do not reflect EPA policy, endorsement, or action, and EPA does not verify the accuracy or science of the contents of the blog.

Editor's Note: The opinions expressed here are those of the author. They do not reflect EPA policy, endorsement, or action, and EPA does not verify the accuracy or science of the contents of the blog.

Please share this post. However, please don't change the title or the content. If you do make changes, don't attribute the edited title or content to EPA or the author.