Components of the Solar System II

The Moon:

A moon is an object that orbits a planet. Objects that orbit other objects are also called satellites, so moons are sometimes called natural satellites. The Moon is 3,474.8 km in diameter and its distance from Earth is 384,400 km.

There is no water or air on the Moon, therefore, the moon’s surface is dry. The Moon’s surface experiences a wide range of temperatures, during the day it is about 120°C and at night it is about -180°C.

The moon is the largest and brightest object we see in the sky from Earth at night. The Earth only has one moon. It does not generate light on its own, rather it reflects the light from the sun. Therefore, only the part of the moon that faces the sun shines (the entire moon cannot shine at once). Even when we think we see a full moon, this is not true, the moon appears in phases. A Moon phase is the apparent shape of the Moon as viewed from the Earth when it is hit directly by sunlight. The four primary phases of the Moon on Earth are the new moon, first quarter, full moon, and last or third quarter.

It takes the moon 28 days to revolve around the Earth. This is the same time it takes for the Moon to rotate once on its axis. Therefore, the same side of the moon is always facing the Earth.

The Moon’s surface consists of mountains, dry planes, and craters. The gravitational pull on the moon is less than on Earth because there are fewer materials on the Moon. The weight of an object on the Moon is \(\frac{1}{6} \scriptsize th\) (0.16) the weight on Earth. Therefore, an object that weighs 150 kg on Earth will weigh 24 kg on the Moon. This is why a person can jump higher on the Moon than on Earth.

The first man to land on the moon was Neil Armstrong, on 21st July 1969. He was accompanied by Aldrin and Collins, two other American astronauts.

Eclipse:

In the same way, that the Earth revolves around the sun, the moon also revolves around the Earth.

An Eclipse is formed when the three bodies – the sun, Earth, and moon are in a straight line. As the Moon and Earth are constantly moving, sometimes the light from the Sun is obscured by either the Moon or the Earth. This occurrence is known as an Eclipse.

There are two types of Eclipses, these are:

i. Solar Eclipse (or Eclipse of the Sun).

ii. Lunar Eclipse (or Eclipse of the Moon).

Please Note: An Annular Eclipse occurs when the Moon is directly between the Earth and the Sun, but the Moon does not completely cover the Sun’s disk. Instead, it covers most of the Sun, leaving the Sun’s outer edge visible as a bright ring or “annulus” around the darkened Moon.

Solar Eclipse:

A Solar Eclipse occurs when the Moon comes in between the Earth and the Sun in a perfectly straight line. This causes the moon to cast its shadow on the Earth causing darkness in certain parts of Earth. This type of Eclipse may either be Partial or Total.

• A Partial Solar Eclipse occurs when the Moon passes between the Sun and Earth but the Sun, Moon, and Earth are not perfectly lined up. A part of the Sun will appear covered, giving the sun a crescent shape.
• A Total Solar Eclipse occurs when the Moon passes between the Sun and Earth, completely blocking the Sun. People viewing the eclipse from locations where the Moon’s shadow completely covers the Sun will experience a total solar eclipse. This is known as the path of totality.

Lunar Eclipse:

A Lunar Eclipse occurs when the Earth comes in between the Moon and the Sun, the Earth, being larger than the Moon, blocks the Sun’s light from reaching the Moon. This type of Eclipse may either be Partial or Total.

• A Partial Lunar Eclipse occurs when the Earth moves between the Sun and Moon but the three celestial bodies do not form a straight line in the Solar System. When this happens, a small part of the Moon’s surface is covered by the darkest, central part of the Earth’s shadow, this part is called the umbra. The rest of the Moon is covered by the outer part of the Earth’s shadow called the penumbra.

• A Total Lunar Eclipse occurs when the Sun, Earth, and Moon are precisely aligned and the Moon passes into the shadow of the Earth. In other words, the Earth is preventing sunlight from reaching the Moon.