The Frequency of Solar and Lunar Eclipses

Solar and Lunar Eclipse: Reason Behind Their Duration and Frequency

The solar and lunar eclipse is a natural phenomenon that occurs when there is an interception of the sun rays done by the moon or the earth. When the moon comes between the sun and the earth, we witness a solar eclipse. When the earth comes between the sun and the moon, we witness a lunar eclipse. In this section, we will discuss the frequency of solar and lunar eclipses and how long they last. We will also learn the reason behind the frequency of these eclipses.


What is a Solar Eclipse?

You have studied solar eclipse in the previous classes. It happens when the moon comes in between the earth and sun interrupting the sun rays emitted from the sun. These rays were supposed to fall on the earth’s surface. When blocked, the sun in the umbra region is totally intercepted by the moon. A partial interception occurs in the penumbra region. As per the calendar we use, solar eclipse generally occurs 2 to 5 times a year. In the year 1935, 5 solar eclipses have occured and it will happen again in 2206. The total number of solar eclipses is 66 on average.


How Long Does a Solar Eclipse Last?

As per the calculations, the solar eclipse that occurred between 1901 and 2000 is 228. Between 2001 and 2100, the total eclipses that will occur are 224. In fact, these calculations suggest that a point on the earth will experience one total solar eclipse in 3 to 4 centuries. This is how often solar eclipses occur in a particular location. Solar eclipses last for only 7.5 minutes.


What is a Lunar Eclipse?

As mentioned earlier, a lunar eclipse occurs when the earth comes in between the sun and the moon. It happens at night on full moon day. The entire moon stops receiving sun rays from the sun and turns out to be lack. The engulfment of the moon by the earth’s shadow occurs for an hour. The lunar eclipse duration is much more than the solar eclipse. It happens due to the reason that the earth’s diameter is greater than the moon. Hence, the shape of the earth’s shadow totally engulfs the moon for a longer period of time.


How Many Times Does a Lunar Eclipse Occur in a Year?

This is the difference between the solar and lunar eclipse. A lunar eclipse occurs two times a year generally. There is no particular count of the lunar eclipse in a year. In some years, it can occur thrice and in some none. Despite the fact, an observer can witness at least 19-20 lunar eclipses within a time span of 18 years. The eclipses can be total or partial.


The frequency of solar and lunar eclipses shows the difference in the geometry of these cosmic bodies. The diameter of the moon is way less than that of the earth. As we know that the lunar eclipse occurs due to the earth’s shadow cast, the pan of this shadow increases the frequency of the lunar eclipse. If you check how long a solar eclipse lasts, you will clearly understand the difference. As the moon’s diameter is quite smaller than the sun, the occurrence of this eclipse is less at a particular point. The differences in the geometrical shape and diameter of these heavenly bodies also decide the span of eclipses.


It takes an hour or more to complete a lunar eclipse due to the huge difference between the earth’s diameter and the moon’s diameter. Similarly, the sun’s diameter is multiple times bigger than the moon’s. Hence, the latter can only guard the sun for 7.5 minutes whereas the earth’s shadow covers the moon for an hour.


What is the Frequency of Solar and Lunar Eclipses?

The difference in the solar and lunar eclipses can be easily explained by the geometry of these bodies. The frequency of solar and lunar eclipses depends on the span of the moon and the earth. Remember that every new moon will not cause a solar eclipse or every full moon will experience a lunar eclipse at night. It happens only when the planes of the sun, earth, and the moon intersects. The plane of the earth’s orbit and that of the moon has a difference of 5°. This makes a huge difference as the moon can easily pass through it during the full moon and new moon days.


The solar eclipse occurs on a new moon day where the moon overshadows the sun for a particular location for only 7.5 minutes. The earth covers the moon for more than an hour on a full moon night. If we consider these phenomena then the frequency of solar and lunar eclipse can be determined. A solar eclipse occurs at least 66 times as a whole in a century. A lunar eclipse occurs at least 19-20 times in a span of 18 years.

FAQs (Frequently Asked Questions)

1. What is the Duration of the Lunar Eclipse?

A lunar eclipse occurs when the earth’s shadow covers the moon on a full moon night. The moon is closer to earth than the sun, the earth’s shadow increases in size. In fact, the earth’s diameter is also much greater than the moon. This is the reason why the lunar eclipse duration is at least an hour. It takes an hour for the moon to cross the earth’s shadow and receive solar rays again to glow at night.

2. What is the Duration of the Solar Eclipse?

A solar eclipse takes only once at a point on the earth’s surface in 3-4 centuries. It is because the moon is much smaller than the sun. Its diameter is much less than the sun. Hence, its shadow falling on the earth will also have a smaller span. An observer will find the time span of a solar eclipse to be 7.5 minutes due to the same reason.

3. When Does a Solar and Lunar Eclipse Happen?

A solar eclipse happens on a new moon day when the moon comes in between the earth and the sun. A lunar eclipse happens on a full moon night when the earth comes in between the sun and the moon.