A solar eclipse occurs when the Moon moves between the Sun and Earth, blocking the Sun’s light and casting a shadow of the Moon on the Earth’s surface.
Solar eclipses only occur during the new moon.
If you want to observe a solar eclipse, you must be in the path of the Moon’s shadow. The Moon’s shadow has 3 distinct parts:
- Shadow (Shadow): This is the innermost and darkest part of the Moon’s shadow. Sunlight is blocked where shadows pass. When you are in this area, the solar disk will no longer be present. Residents of this area will be able to see the total solar eclipse.
- Twilight (Penumbra): Is the outermost and brightest part of the Moon’s shadow. Only part of the Sun is obscured where the penumbra passes. The solar disk now only partially appears. Residents in this area will be able to see the partial eclipse.
- The opposite of shadow (Antumbra): This area is behind the shadow area. It only appears on the Earth’s surface when the Moon is further away. (The Moon moves around the Earth in an elliptical orbit. Depending on the time of the new Moon, the Moon is far or close to the Earth). From Earth, the Moon appears smaller and cannot completely obscure the Sun, so the outer edge of the Sun is still visible. People in this area will see the annular solar eclipse.
Figure 1: The Moon’s umbra blocks sunlight from reaching the Earth’s surface, while the penumbra causes a partial eclipse over a larger area.
Photo: Time and date.
There are four types of solar eclipses and they are determined by the Moon’s shadow areas on the Earth’s surface.
- Total solar eclipse: A total solar eclipse occurs when the Moon completely obscures the Sun and forms umbras and penumbras on the Earth’s surface. A total solar eclipse can only take place when the Moon is around the orbit point. You can observe a total solar eclipse when you are in the path of the Moon’s shadow. People who are not in shadow but are in penumbra will be able to observe the partial eclipse.
- Partial eclipse: A partial solar eclipse occurs when the Moon does not completely obscure the solar disk and forms only a penumbra on the surface of the Earth.
- Annular solar eclipse: An annular solar eclipse occurs when the opposite region of the shadow appears on Earth. The Moon’s disk will obscure the central region of the Sun’s disk, revealing the Sun’s ring-shaped outer edge. An annular eclipse can only occur when the Moon is around its apogee.
- Hybrid Eclipse: Hybrid eclipses are very rare. They occur when an annular eclipse turns into a total eclipse.
Figure 2: Depending on the distance between the Moon and the Earth, on the Earth’s surface there can be umbra (umbra), penumbra (penumbra) and opposite areas of the umbra (antumbra) . Depending on the position of the observer in umbra, penumbra or umbra, the observer can see a total solar eclipse (A), an annular solar eclipse (B) or a partial solar eclipse (part C). Photo: Wikipedia.
For a solar eclipse to occur, the Sun, Moon and Earth must be on a straight or nearly straight line – this alignment is called by astronomers. syzygy. This can only happen during the new moon.
Although a new moon is required for a solar eclipse to occur, a solar eclipse does not occur every new moon. Because the orbital plane of the Moon around the Earth is inclined at an angle of about 5° with respect to the orbital plane of the Earth around the Sun (plane of the ecliptic). The places where these two orbital planes meet are called lunar nodes. A solar eclipse only occurs when a new moon appears near this node.
The Sun must also be located near the nodal point so that the three objects can stand in a perfect or nearly perfect straight line. This arrangement takes place twice a year and usually ends after approximately 34.5 days. This cycle is called “eclipse season”. There are approximately 2-3 solar and lunar eclipses that occur during each solar and lunar eclipse season.
A lunar month (lunar month) is the cycle from one new moon to the next new moon. The lunar month lasts about 29 days and is shorter than the solar and lunar eclipse season. Therefore, there will be at least 1 new moon and 1 solar eclipse, with at least 1 full moon and 1 lunar eclipse occurring during the solar-lunar eclipse season. This means that solar and lunar eclipses tend to occur in pairs – a solar eclipse always occurs 2 weeks before or after a lunar eclipse.
Figure 3: 3D illustration of a solar eclipse, in which the green line is the Moon’s orbit around the Earth, the blue line is the Earth’s orbit around the Sun. If the Moon is at perigee, a total solar eclipse will occur. Only when the Moon is on the same side as the Sun (new moon) can a solar eclipse occur. Photo: Wikipedia.
If we ignore hard-to-detect penumbral eclipses, then the number of solar eclipses will be about 3/2 more than that of lunar eclipses. On average, there can be 240 solar eclipses and around 150 lunar eclipses per century.
However, for most people, a solar eclipse is clearly rarer than a lunar eclipse. There are 2 reasons to explain this paradox:
- We live on Earth, which creates darkness during a lunar eclipse, so anyone on the dark side of Earth can observe the eclipse. For a solar eclipse, you must stand on a narrow band which constitutes the path of the Moon’s shadow to be able to observe this phenomenon.
- Lunar eclipses tend to last longer than solar eclipses. The theoretical maximum duration of a total solar eclipse is about 7 and a half minutes, while a total lunar eclipse can last up to 100 minutes.
Fun fact: On average, a total lunar eclipse is visible from any location every 2.5 years, while it takes 375 years for a total solar eclipse to occur from the same location on Earth.
Almost every year there are about 4 solar and lunar eclipses, which is the minimum number of solar and lunar eclipses that can occur in a year. 2 out of 4 solar and lunar eclipses must be solar eclipses. In a year, up to 7 solar and lunar eclipses can occur, but this is very rare (5 solar eclipses and 2 lunar eclipses, or 2 solar eclipses and 5 lunar eclipses).
There can be a minimum of 2 and a maximum of 5 solar eclipses per year. Out of these, no more than 2 solar eclipses can be total solar eclipses. It’s very scary when there are 5 solar eclipses in the same year.
According to NASA calculations, only about 25 times in the last 5,000 years has the world experienced 5 solar eclipses in the same year. The last occurred in 1935, and the next will be in 2206, when there will be two total solar eclipses in December.
Solar eclipses tend to occur in cycles, called the solar-lunar eclipse cycle. Astronomers and scientists use the cycle of solar-lunar eclipses to predict and calculate their future occurrences. One of the most popular solar-lunar eclipse cycles is the Saros cycle. The ancient Babylonians used it to predict lunar eclipses.
The Saros cycle is a cycle of approximately 6,585.3 days, or approximately 18 years, 11 days and 8 hours, and occurs based on the combination of 3 lunar cycles:
- Synodic month: the time between two consecutive new moons.
- Month of perigee (abnormal month): the time between two consecutive moments when the Moon is at perigee.
- Dragonic month: the time between two consecutive lunar nodes.
The two eclipses separated by the Saros cycle are typically similar: they occur at the same lunar node, with the Moon being approximately the same distance from Earth. Solar and lunar eclipses also occur around the same time of year and at almost the same time of day.
Via: VLTV – Source: TimeAndDay
