Eclipses occur when the Sun, the Moon, and Earth line up, either fully or partially. Depending on how they align, eclipses provide a unique, exciting view of either the Sun or the Moon.
Solar EclipsesSolar Eclipses
A solar eclipse happens when the Moon passes between the Sun and Earth, casting a shadow on Earth that either fully or partially blocks the Sun’s light in some areas. This only happens occasionally, because the Moon doesn't orbit in the exact same plane as the Sun and Earth do. The time when they are aligned is known as eclipse season, which happens twice a year and lasts for about 35 days each.
Except for the fleeting moments of totality during a total solar eclipse, when watching a partial, annular, or hybrid solar eclipse, or before or after totality in a total solar eclipse, eclipse viewers should always use eclipse glasses or an alternative solar viewing method, such as a pinhole projector. Learn more about viewing a solar eclipse safely, here.
Total Solar Eclipse
A total solar eclipse happens when the Moon passes between the Sun and Earth, completely blocking the face of the Sun. People located in the center of the Moon’s shadow when it hits Earth will experience a total eclipse. The sky will become very dark, as if it were dawn or dusk. Weather permitting, people in the path of a total solar eclipse can see the Sun’s corona, the outer atmosphere, which is otherwise usually obscured by the bright face of the Sun. A total solar eclipse is the only type of solar eclipse where viewers can momentarily remove their eclipse glasses (which are not the same as regular sunglasses) for the brief period of time when the Moon is completely blocking the Sun. The next total solar eclipse in the U.S. will be on April 8, 2024.
Annular Solar Eclipse
An annular solar eclipse happens when the Moon passes between the Sun and Earth, but at its farthest point from Earth. Because the Moon is farther away from Earth, it appears smaller than the Sun and does not completely cover the star. As a result, the Moon appears like a dark disk on top of a larger, bright disk, creating what looks like a ring around the Moon. The next annular eclipse in the U.S. will be on Oct. 14, 2023.
Partial Solar Eclipse
A partial solar eclipse happens when the Moon passes between the Sun and Earth but the Sun, Moon and Earth are not perfectly lined up. The Sun appears to have a dark shadow on only part of its surface. During a total or annular solar eclipse, people outside the area covered by the Moon’s inner shadow see a partial solar eclipse.
Hybrid Solar Eclipse
Sometimes an eclipse can shift between annular and total as the Moon’s shadow moves across Earth’s surface. This is called a hybrid solar eclipse.
Lunar EclipsesLunar Eclipses
The Moon orbits Earth, and at the same time, Earth orbits the Sun. Sometimes Earth passes between the Sun and the Moon. When this happens, Earth blocks the sunlight that normally is reflected by the Moon — which we see as moonlight — casting a shadow on the Moon. This is an eclipse of the Moon: a lunar eclipse.
This is different than the Moon’s phases we see changing throughout the month. These phases occur because, at times, the Sun is illuminating areas of the Moon that we can’t see on Earth, while the Moon is orbiting Earth. A lunar eclipse can occur only when the Moon is full, which is when sunlight completely illuminates the Moon.
A lunar eclipse usually lasts for a few hours. There are three types of lunar eclipses. At least two partial lunar eclipses happen every year, but total lunar eclipses are rare. Unlike a solar eclipse, it is safe to look at a lunar eclipse with the naked eye.
Total Lunar Eclipse
A total lunar eclipse occurs when the Moon and the Sun are on exact opposite sides of Earth. Although the Moon is in Earth's shadow, some sunlight still reaches it. The sunlight passes through Earth's atmosphere, which tends to preferentially scatter and absorb shorter wavelengths of blue light. This makes the Moon appear red to people on Earth.
Partial Lunar Eclipse
A partial lunar eclipse happens when only part of Earth’s shadow covers the Moon. In a partial lunar eclipse, Earth's shadow appears very dark on the Moon. The amount of the Moon that’s covered – or eclipsed – depends on how the Sun, Earth, and Moon are lined up.
Penumbral Lunar Eclipse
During a penumbral lunar eclipse, the Moon travels through Earth’s penumbra — the faint, outer part of Earth’s shadow. The Moon only dims slightly when this happens.
