Description: A solar eclipse occurs when the Earth, Moon, and the Sun are arranged in a straight line, with the Moon between Earth and the Sun. When observed from the surface of the Earth, the disk of the Moon covers the disk of the Sun in the sky; from space we can see the shadow of the Moon moving across the sunlit side of the Earth.

There are different types of solar eclipses. Total, when the disk of the Moon completely covers the Sun; partial, when only a fraction of the solar disk is covered even at maximum eclipse; and annular, when the Moon is farther away than average and hence appears smaller than usual allowing a ring of the solar disk to remain visible even at the maximum extent of the eclipse.

During a total solar eclipse, the darkest point of the shadow of the Moon on Earth is called the "umbra", and the edge of the shadow is called the "penumbra". Observers in the umbra see a total eclipse while observers in the penumbra see a partial eclipse.

Related Terms:

• Eclipse
• Moon
• Sun
• Shadow

Term and definition status: This term and its definition have been approved by a research astronomer and a teacher

The OAE Multilingual Glossary is a project of the IAU Office of Astronomy for Education (OAE) in collaboration with the IAU Office of Astronomy Outreach (OAO). The terms and definitions were chosen, written and reviewed by a collective effort from the OAE, the OAE Centers and Nodes, the OAE National Astronomy Education Coordinators (NAECs) and other volunteers. You can find a full list of credits here. All glossary terms and their definitions are released under a Creative Commons CC BY-4.0 license and should be credited to "IAU OAE".