The event is known as an annular eclipse, when the moon moves directly between the Earth and the sun, producing a striking ring of fire effect. During annular eclipses, the new moon's apparent diameter is smaller than the visible disk of the sun. (See annular eclipse pictures.)
Since the moon's orbit is elliptical, its distance from Earth changes periodically. During an annular eclipse, the moon is farther from Earth, so its apparent size is smaller than the solar disk.
Today's annular eclipse first appeared over Western Australia at sunrise and swept across portions of Papua New Guinea and the Solomon Islands, before crossing much of the Pacific Ocean.
Eclipse expert and National Geographic grantee Jay Pasachoff staked out a viewing spot in Australia's outback along the path of annularity along with over a hundred other eclipse-watchers from around the world.
"We can report good success in observing 4 minutes and 20 seconds of full annularity at the eclipse today," he said in an email to National Geographic.
"Much of the eclipse was viewed through thin clouds, though rarely after the first few minutes was the sun obscured."