Illustration of the city lights on a dark Earth during a solar eclipse.

IMAGE SPECS: Royalty Free

Description:
The perspective in this image is looking down on the Indian Ocean from an altitude of 25,000 miles. On the Earth's night side artificial lights clearly define the Mediterranean Sea, Red Sea, and almost the entire African continent, while clouds obscure some of Europe and India. The alignment with the Moon and Sun is such that at this moment a total eclipse of the Sun is visible revealing the Sun's brilliant corona. However the area of totality, i.e., the darkest part of the Moon's shadow, is so small, less than 200 miles wide, that observers on the Earth would not be able to see this total eclipse. The only portion of the eclipse visible from the Earth is in the eastern Indian Ocean where the Moon's penumbra (partial shadow) falls, as can be seen in this image. The fact that total solar eclipses are visible at all is due in part to one of the most amazing coincidences in the Solar System: the Sun and the Moon appear from Earth to be about the same size in the sky. This is because the Sun's diameter is both 400 times that of the Moon's and is about 400 times as far away from the Earth. The result is that from the Earth, the Moon appears to just barely cover the Sun. If the Moon's diameter were reduced by just 6%, or if it were a little further away, it would never be large enough to ever completely cover the Sun.