annular solar eclipses

Annular eclipses happen in exactly the same way as total eclipses except that the Moon appears smaller in the sky than it does for a total eclipse. Why does the Moon look smaller? The Moon orbits the Earth in an ellipse and so its distance from the Earth changes continuously during the month.

An annular eclipse can be seen in this series of photographs by Fred Espenak.

The Moon's orbit is changing. The Moon's average distance from Earth is increasing, by about 1.5 metres every century. In about 170 million years, it will always be too far away from the Earth to ever cause a total solar eclipse. Because it will always appear smaller in the sky, the best solar eclipse there will be in that far-off future is an annular eclipse. Make sure you see a total solar eclipse while you still can!