Eclipses – Solar Eclipses & Lunar Eclipses

Eclipses

 Key Concepts

• Moon
• Eclipse
• Lunar eclipse
• Solar eclipse

Introduction

The Moon has been a cause of surprise throughout history. We know that currently, the moon does not have a magnetic field. Rock samples obtained from the moon have given the early history of the Earth. Before the invention of the telescope, some observers said that they saw faces on the Moon’s surface. When the moon is seen from the telescope, its face vanishes, and dark and light-colored areas with bowl-shaped holes are seen on the moon’s surface. Apollo astronauts, when they visited the Moon, they took pictures of all sorts of features present on the moon. Some of the features of the moon looked the same when seen from Earth. 

Planets and Orbits

We all know that gravity is the force of attraction among all objects. Gravity causes a thing to fall on to the floor, and this force keeps planets in their orbit. The amount of gravitational force between the sun and the planet depends on its mass. The higher the mass of the object, the attraction will be greater between them. Distance is also one of the factors that affect gravitation. The higher the distance between the planets and the sun, the lower will be the pull of gravity. 

The planets revolve in orbit due to inertia. Inertia is the tendency of a moving thing to remain in motion. Gravity will pull objects, i.e., planets, towards the sun, because of the huge mass of the sun. This does not take place because the planets have inertia, and they are moving. Inertia causes the planets to move in straight lines. The balance between the force of gravity and the inertia of the planets keep the planets moving in their orbits around the sun. The movement of planets is in a straight line due to inertia, but gravity pulls the planets and makes their path in a curved shape into orbits around the sun. 

Moon: 

We know that the Earth revolves around the Sun whereas the Moon revolves around the Earth. When we look at the Moon, we feel that the Moon has changed its shape. The shape of  Moon does not change but we see the  area of lighted side of the Moon, hence we feel that the shape of moon is changed. The Moon does not have its own light; it reflects the light that falls on it from the sun. Half side of the Moon always looks towards the sun and hence is lit by the sun rays. The other side of the Moon is always dark because it is away from the Sun rays. At the time of the new Moon, the Moon comes between the Sun and the Earth. Due to this, we see the various shapes of the Moon in the sky is called the phase of the Moon. 

Eclipses: Lunar Eclipse 

In space, when one object crosses in front of the second object, the first object can block the view of the second object; this causes eclipses. There are two types of eclipses – lunar eclipse and solar eclipse. Lunar eclipse is of 3 types – total lunar eclipse, partial lunar eclipse and penumbral lunar eclipse. Lunar eclipse can occur maximum 3 times in a calendar year. 

In space, when the Earth blocks sunlight that reaches the Moon, it causes a total lunar eclipse. The Moon is usually above or below the Earth because the Moon’s orbital path is tilted (inclined) as compared to the Earth’s path around the sun. Every month, the moon crosses the path of Earth’s orbit. This happens at the time of a full Moon, here the Moon can pass directly through the Earth’s shadow; hence direct sunlight does not fall on the Moon. 

The Moon becomes dark until it is in the Earth’s shadow and becomes visible when the Sun’s light falls on it. In the course of a total lunar eclipse, the color of the Moon may look reddish. Sometimes it is also called the blood Moon due to its color. The various shades of color depend on the interaction of sunlight with the Earth’s atmosphere on its way to the Moon. Partial lunar eclipse occurs when the Moon passes through a part of the Earth’s shadow. Here, three celestial bodies – the Sun, the Earth and the Moon do not form the same line. Partial lunar eclipse is more common than the total lunar eclipse. 

When only the outer part of the Earth’s shadow covers the Moon, a penumbral lunar eclipse takes place. This eclipse is very difficult to occur. In this eclipse, the moon’s complete disk is covered in the penumbra. 

Types of shadow in Eclipse: 

There are 3 different types of shadows that cause different types of solar and lunar eclipses. 

When the Moon’s shadow falls on the Earth, we see a solar eclipse. When the Earth’s shadow falls on the Moon, it results in a lunar eclipse. But there are various types of solar and lunar eclipses. A solar eclipse may be total, partial, or annular, and a lunar eclipse may be total, partial, or penumbral. 

The Moon and the Earth cast 3 shadows namely – umbra, penumbra and antumbra. 

An umbra: It is the dark center area of a shadow. The Moon’s umbra produces total solar eclipses, and the Earth’s umbra produces total and partial lunar eclipses. 

Penumbra: It is the lighter outer portion of the shadow. Earth’s penumbra causes a penumbral lunar eclipse. 

An antumbra: The lighter portion of a shadow that forms at a certain distance from the object that causes the shadow.  

Solar eclipse: 

A total solar eclipse occurs when the Earth passes through the Moon’s shadow. When the moon comes between the Sun and the Earth in a straight line, a total solar eclipse occurs. Only during a new moon, solar eclipse occurs. 

In the course of a total solar eclipse, the Moon covers the complete disk of the Sun; hence the body of the sun looks completely dark; whereas in case of partial and annular solar eclipses, the Moon covers only a part of the Sun. Total solar eclipse do not last for very long and do not occur very frequently. When a solar eclipse occurs, it does not occur from every part of the Earth. The moon’s dark shadow, or umbra, is small. The moon produces its shadow over a very small area of the Earth’s surface; hence only observers present inside the umbra region will be able to see a total solar eclipse. Others may see a partial solar eclipse. 

Usually, the Moon and the Sun do not come in an exact straight line, so in such a situation, the Sun’s disk is only partially blocked. The sun rays are very strong, and they can burn our eyes and damage the retina. So, always wear protective glasses to see the sun and the total solar eclipse.  

Summary

• Summary The amount of gravitaional force between the sun and the planet depends on the mass.
• Inertia is the tendency of a moving thing to remain in motion.
• The Earth revolves around the Sun, whereas the Moon revolves around the Earth.
• The Moon does not have its own light; it reflects the light that falls on it from the Sun.
• When the Earth blocks sunlight that reaches the Moon, it causes a total lunar eclipse.
• Partial lunar eclipse occurs when, the Moon passes through a part of the Earth’s shadow.
• The Moon and the Earth cast 3 shadows namely – umbra, penumbra and antumbra.
• A total solar eclipse occurs when, the Earth passes through the Moon’s shadow.