Greetings from Ocracoke! Another Morehead educator and I are teaching a weeklong astronomy seminar for the North Carolina Center for the Advancement of Teaching (NCCAT). If you have friends or family who are North Carolina public school teachers who haven’t been to an NCCAT renewal seminar, please tell them to check it out.
This is it! The biggest astronomical event of the year: a total lunar eclipse on Wednesday, Feb. 20, 2008.
The eclipse’s timing is great for east coast skywatchers. The Moon will start to move into the darkest part of the Earth’s shadow at 8:43 p.m. It will slowly be enveloped by the Earth’s shadow until it is totally eclipsed at 10:01 p.m. Totality will last until 10:51 p.m. By 12:09 a.m., it will have moved out of the darkest part of the Earth’s shadow.
Morehead Planetarium and Science Center is holding a skywatching session around our Sundial at 250 E. Franklin St in Chapel Hill from 8:30 to 11:00 p.m. We’ll have telescopes set up so that you can get an up close look at the eclipse, and Morehead staff will be there to guide you and answer questions.
People have all sorts of misconceptions about eclipses (have you heard any misconceptions about eclipses or the Moon? Please tell me about them!). A solar eclipse happens when the Moon moves in front of the Sun and blocks part or all of its light. A lunar eclipse happens when the Moon moves into Earth’s shadow. Earth always casts a shadow, but only once or twice a year on average does the Moon actually pass through it. It’s logical to think that a lunar eclipse would occur once a month, as the Moon orbits Earth; however, since the Moon’s orbit is slightly tilted relative to Earth’s orbit around the Sun, the Moon usually passes above or below Earth’s shadow.
Once the eclipse reaches totality, you’ll notice that you can still see the Moon, and it becomes a rusty brown color. Even though the Earth is completely blocking the Sun, the Moon is still receiving a little bit of light that passes through Earth’s atmosphere – light from all of the sunrises and sunsets around the world. That’s why it looks slightly red. If you'd like to learn more about the effects of Earth's atmosphere on the Sun's light, read my "Ask Morehead" blog post named "Why is the Sky Blue?"
It’s cool to imagine what a lunar eclipse would look like from the Moon’s surface. If astronauts were hanging out on the Moon Wednesday night, they would see the Earth appear to move in front of the Sun. The Sun and Moon are almost exactly the same apparent size in our sky, but from the surface of the Moon, the Earth would appear much bigger than the Sun – about three times its apparent diameter.
The next total lunar eclipse won’t happen until December 21, 2010, so get outside and watch this one!
For more information on Morehead Planetarium and Science Center's programs and skywtaching sessions, visit www.moreheadplanetarium.org