Solar eclipse
A solar eclipse occurs when the Moon passes between Earth and the Sun, blocking some or all of the Sun’s disk from view in parts of Earth.
Umbra: The darkest central region of a shadow, where an opaque object blocks the light source completely. Observers inside the Moon’s umbra see the Sun fully covered during totality.
Total solar eclipse: A solar eclipse in which the Moon completely covers the Sun’s visible disk for observers in a narrow path. The Moon’s umbra reaches Earth, briefly revealing the solar corona along a narrow track.
Moon's orbit: The path the Moon follows around Earth, inclined about five degrees to the plane of Earth’s orbit. Its inclination usually carries the new Moon above or below the Sun in the sky.
Solar corona: The Sun’s outer atmosphere, extending millions of kilometers into space and reaching temperatures of millions of kelvins. Totality briefly makes the corona visible against the darkened sky.
Lunar eclipse: An astronomical event in which Earth passes between the Sun and the Moon, casting its shadow on the Moon. The body entering shadow is the Moon, reversing the alignment of a solar eclipse.
Penumbra: The lighter outer region of a shadow, where an object blocks only part of a light source. The Moon’s penumbra produces partial eclipses across a much broader area than its umbra.
Annular solar eclipse: A solar eclipse in which the Moon appears smaller than the Sun and leaves a bright ring visible. The Moon’s antumbra reaches Earth when the Moon’s apparent disk cannot cover the Sun.
Eclipse season: A period, occurring about every six months, when the Sun is near a lunar orbital node and eclipses can occur. A new Moon during this interval can align closely enough to produce a solar eclipse.
Baily's beads: Brief points of sunlight that shine through lunar valleys near the beginning or end of totality. Their appearance during eclipse contacts reflects the Moon’s rugged limb.
Transit of Venus: An event in which Venus passes directly between Earth and the Sun, appearing as a small silhouette on the solar disk. Venus crosses the Sun without covering its disk, unlike the nearby, larger-appearing Moon.