Home Page A lunar eclipse happens when the Moon passes into the Earth's Shadow.
Lunar eclipses are common.
On average they happen twice a year. So it was a special opportunity to see a lunar eclipse during a semester I'm teaching Introductory Astronomy at Schoolcraft College. I was pleased to see that most had produced respectable sketches showing the curve of the Earth's shadow. This meant we had the data to measure the relative sizes of the Earth and Moon, just as the ancient Greek astronomer Aristarchus had done 2300 years ago. The Moon orbits the earth roughly every 30 days or so.