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Eclipses

The picture at right shows what happens during a Lunar Eclipse. The diagram is not to scale, that is, the Earth is much farther away and smaller than it is shown here. Because the moon's orbit is slightly tilted by 5 about degrees, eclipses do not happen every month but vary from 6 months to 30 months apart. As the moon reaches line A it begins to enter the Earth's shadow. Part of the sun is still shining on it so it is not totally dark. At line B the moon is about half dark. Some of the sun's light seeps through the Earth's atmosphere and turns the shadow reddish. At C the moon is coming out of the darkest part of the shadow. At D the moon is fully lit again. It takes about 5 hours to move from line A to line D.

A Solar Eclipse is similar except that the moon is much smaller than the Earth so it doesn't completely shadow it. The diagram at left shows the moon's shadow covering part of the Earth. Lines A and B are where the sun's light is blocked by the moon. Again, the drawing is not to scale. Solar eclipses happen from about 9 to 30 months apart.

Click image or here for a 262K NASA animation of the eclipse. The background is a light color so you can see the shadows. Behind the moon there is a darker cone of shadow that makes a black dot on the Earth known as the totality. If you are standing in this part of the shadow, the sky turns as dark as night for about two minutes or so.

The Diamond Ring

Just before the moon completely covers the sun, mountains on the moon allow a bit of light to peek through creating this beautiful diamond ring effect at right. This image was taken by an Apollo Mission crew as they went behind the moon on their way back to Earth.

Bailey's Beads are a similar effect that look like a string of pearls along the edge of the shadow.

The table below lists some recent and future total eclipses for North America. There are occasions where the eclipse is only partial so are not listed here. Find out more dates at the US Naval Observatory's Official Times and Dates site.