LEARN ABOUT ECLIPSES!
WHAT IS AN ECLIPSE?
An eclipse occurs when one celestial body passes in front of a second celestial body as seen from a third celestial body. In other words, an eclipse occurs when 3 bodies line up, resulting in total or partial blocking of one body as seen from another. The fun-to-say scientific term for this is “syzygy”!
From Earth, we can see two types of eclipses —eclipses of the Sun (solar eclipses) and eclipses of the Moon (lunar eclipses).
SOLAR ECLIPSE
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As seen from the Earth, a solar eclipse occurs when the Moon passes in front of the Sun and casts its shadow on Earth. Solar eclipses happen once every 18 months and only last for a few minutes.
A total solar eclipse occurs when the Moon completely covers the Sun, as seen from Earth. This total eclipse happens about every year and a half somewhere on Earth. A total solar eclipse is only visible from a small area on Earth. The people who see the total eclipse are in the center of the moon’s shadow when it hits Earth. The sky becomes very dark, as if it were night. For a total eclipse to take place, the Sun, Moon and the Earth must be in a direct line.
A partial solar eclipse occurs when the Sun, Moon and the Earth are not exactly lined up. A partial solar eclipse happens at least twice a year somewhere on Earth. During a partial solar eclipse, the sun appears to have a dark shadow on only a small part of its surface.
An annular solar eclipse happens when the moon is farthest from Earth. Because the moon is farther away from Earth, it seems smaller. It does not block the entire view of the sun. The moon in front of the sun looks like a dark disk on top of a larger sun-colored disk. This creates what looks like a ring around the moon.
LUNAR ECLIPSE
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As seen from the Earth, a lunar eclipse occurs when the Earth passes between the Sun and the Moon, casting its shadow on the Moon. A lunar eclipse can occur only during a full moon phase. During a lunar eclipse, a full moon fades away as Earth’s shadow covers it up.
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 reaches the moon. The sunlight passes through Earth's atmosphere, which causes Earth’s atmosphere to filter out most of the blue light. This makes the moon appear red to people on Earth.
A partial lunar eclipse happens when only a part of the moon enters Earth's shadow. In a partial eclipse, Earth's shadow appears very dark on the side of the moon facing Earth.
A penumbral lunar eclipse happens when the Moon travels through the faint penumbral portion of Earth’s shadow.
A lunar eclipse usually lasts for a few hours. At least two partial lunar eclipses happen every year, but total lunar eclipses are rare. It is safe to look at a lunar eclipse.
ECLIPSE & MOON PHASES
A solar eclipse happens at the new moon phase, when the Moon passes between the Sun and Earth.
A lunar eclipse happens at the full moon phase, when the Earth passes between the Sun and Moon.
ECLIPSES EVERY MONTH?
You might be wondering why we don’t have a lunar eclipse every month as the Moon orbits Earth. It’s true that the Moon goes around Earth every month, but it doesn’t always get in Earth’s shadow. The Moon’s path around Earth is tilted compared to Earth’s orbit around the Sun. The Moon can be behind Earth but still get hit by light from the Sun.
TRANSIT & OCCULTATION
Eclipses are not unique to Earth, the Moon and the Sun. Similar phenomena occur between different planets and moons.
A transit occurs when one object appears to pass in front of another object. But in a transit, the apparent size of the first object is not large enough to cast the second into complete shadow. When an apparently small celestial object (like a planet) moves in front of an apparently big one (like the sun), astronomers say that a “transit” has occurred. Occasionally, Mercury or Venus transit across the face of the Sun, as seen from Earth.
An occultation occurs when an apparently big object moves in front of an apparently small object. This is typically the Moon occulting (hiding) a planet or star or a planet occulting a star.
IMAGE CREDITS
timeanddate.com
nasa.gov
spaceplace.nasa.gov
Dani Nandiyanto et al., 2016 (DOI:10.17509/ijost.v1i2.3728)
grade8science.com/
byjus.com
skyandtelescope.org