PHOENIX -- For the first time in over 18 years, an annular eclipse of the sun appeared in the skies across the western United States on Sunday.
In Japan, millions as the rare annular eclipse, darkened the skies over Tokyo early Monday for the first time in more than 170 years.
During the May 20 annular solar eclipse, the moon's orbit was at its furthest distance from Earth, which means the smallest amount of the sun was blocked. This created a large bright ring of light called a "ring of fire" around the outside of the sun.
The eclipse was broadcast live on TV in Tokyo, where such an eclipse hasn't been visible since 1839. The Taipei Astronomical Museum opened its doors at dawn and Hong Kong's Space Museum set up solar-filtered telescopes outside its building on the Kowloon waterfront.
The next solar eclipse will be a total solar eclipse on November 13, 2012.
A solar eclipse should not be confused with a lunar eclipse, which occurs when the Moon passes behind the Earth so that the Earth blocks the Sun's rays from striking the Moon. A lunar eclipse can occur only when the Sun, Earth, and Moon are aligned exactly, or very closely so, with the Earth in the middle. As a result, a lunar eclipse can only occur the night of a full moon.