Shop Windows to the Universe

Dig into Montana Before History: 11K Years of Hunter-Gatherers in the Rockies and Plains by D. H. MacDonald, Ph.D. See our online store book collection.
This image explains how the Earth's shadow causes a lunar eclipse. Notice the difference between the umbra and the penumbra.
Click on image for full size
Windows to the Universe original image

Lunar Eclipses

Lunar eclipses are special events that only occur when certain conditions are met. First of all, the Moon must be in full phase. Secondly, the Sun, Earth and Moon must be in a perfectly straight line. If both of these are met, then the Earth's shadow can block the Sun's light from hitting the Moon.

There are three types of lunar eclipses. Which one we will see depends on the alignment of the three celestial objects. But first, you need to know that the Earth's shadow is broken up into two parts. The umbra is the darker part of the shadow, where no part of the Sun can been seen. The penumbra is lighter than the umbra, because part of the Sun can be seen.

So, when part of the Moon passes through the umbra, this is called a partial eclipse. When all of the Moon passes through the umbra, this is called a total eclipse. Finally, when the Moon only passes through the penumbra, this is called a penumbral eclipse.

Now that you know all about eclipses, you can step outside and enjoy the show! Remember that lunar eclipses are not dangerous to the eye, so you don't need protection to watch. Just find a nice, cozy spot and enjoy!

Last modified June 20, 2001 by Jennifer Bergman.

Shop Windows to the Universe Science Store!

Learn about Earth and space science, and have fun while doing it! The games section of our online store includes a climate change card game and the Traveling Nitrogen game!

Windows to the Universe Community



You might also be interested in:

Traveling Nitrogen Classroom Activity Kit

Check out our online store - minerals, fossils, books, activities, jewelry, and household items!...more

Lunar Eclipse January 20, 2000

The last lunar eclipse of the millennium in North America is this week! On January 20, 2000, which is Thursday for those living in North America, a total lunar eclipse will occur. A lunar eclipse is different...more

Astronomy at Stonehenge

Some people would say that advanced astronomical astronomy was practiced at Stonehenge. But, it is not likely that ancient observers were able to make advanced predictions such as when lunar and solar...more

Total Lunar Eclipse

There will be an eclipse of the Moon on Thursday night, May 15, 2003. It will be the first eclipse in 2003. This eclipse is a total eclipse of the Moon, which means the Moon will pass through the darkest...more

Lunar Eclipse - November 2003

There will be an eclipse of the Moon on Saturday night, November 8, 2003. It will be the second lunar eclipse in 2003. This eclipse is a total eclipse of the Moon, which means the Moon will pass through...more

Eclipse of the Moon in October 2004

There will be an eclipse of the Moon on Wednesday night, October 27, 2004 (or during the wee hours of the morning on the 28th if you are in Europe or Africa). This eclipse is a total eclipse of the Moon,...more

Universal Time

When it is noon where you live, it is midnight on the opposite side of the world. Usually when we think of time, we mean "the time of day where I live". If we say something happened at 9 AM, we mean it...more

Windows to the Universe, a project of the National Earth Science Teachers Association, is sponsored in part is sponsored in part through grants from federal agencies (NASA and NOAA), and partnerships with affiliated organizations, including the American Geophysical Union, the Howard Hughes Medical Institute, the Earth System Information Partnership, the American Meteorological Society, the National Center for Science Education, and TERC. The American Geophysical Union and the American Geosciences Institute are Windows to the Universe Founding Partners. NESTA welcomes new Institutional Affiliates in support of our ongoing programs, as well as collaborations on new projects. Contact NESTA for more information. NASA ESIP NCSE HHMI AGU AGI AMS NOAA