The concept of the solar system

The Sun is a huge celestial body in the solar system. It is the main source of heat and light for all heavenly bodies, including the planets.

In the solar system, all eight planets revolve around the Sun in their elliptical paths called orbits.

The eight planets are

1. Mercury
2. Venus
3. Earth
4. Mars
5. Jupiter
6. Saturn
7. Uranus
8. Neptune.

Each planet revolves around the Sun in its elliptical path called an orbit. Planets are different from stars. Whereas planets do not have their own light, stars have their own light, and that is why we can see them twinkling in the sky during the night.

The orbits around the Sun differ in terms of size and diameter, depending on the distance between the Sun and the position of each planet. However, the planets do not fall from space due to the gravitational force from the Sun that holds the planets in orbit in the solar system. These gravitational forces are equal from both sides.

In the solar system, some planets are close to the Sun while others are far away from the Sun. This causes some of the planets to travel long distances and take many days to revolve around the Sun, while others take a few days to revolve around the Sun. For example, the Earth takes 365¼ days or 366 days to revolve around the Sun.

When you look at the night sky, you can see various heavenly bodies with different shapes and structures. These objects are also present during the day, but they are not visible due to the brightness of the Sun. Besides planets and stars, other celestial objects include

• asteroids.
• comets.
• meteors.

Asteroids

Asteroids are small, solid heavenly bodies in the solar system that revolve around the Sun. They are smaller than planets and are sometimes called planetoids because they resemble planets.

• Asteroids are mainly found in the asteroid belt, located between the orbits of Mars and Jupiter.
• There are many asteroids in space moving at high speed.
• Some asteroids form separate groups and can come closer to Earth.

An asteroid

Comets

Comets are solid heavenly bodies that are smaller than planets and revolve around the Sun. Unlike asteroids, comets consist of a mass of ice containing frozen dust and rock particles.

• Comets move at high speed around the Sun.
• Some comets group together and may come closer to Earth.
• At night, comets appear bright and seem to move quickly, often looking like a bright star with a tail, which is why people sometimes call them "stars with tails."
• When comets are visible with a bright tail, they are often mistakenly called meteorites.

Meteors

Meteors are pieces of rock that fall from outer space. When they enter Earth's atmosphere, they burn and melt due to friction with the air.

• Some meteors burn completely before reaching the ground.
• Those that do not burn completely and land on Earth's surface are called meteorites.
• Tanzania has two well-known meteorites:
  1. Ndolezi Meteorite – Found in Mbozi District, Songwe Region.
  2. Malampaka Meteorite – Found in Maswa District, Simiyu Region.

The mesosphere, a layer in Earth's atmosphere, helps protect the planet from being hit by asteroids, meteorites, and other space objects. Without this protective layer, Earth would be bombarded by millions of falling space rocks, making life on Earth impossible.