The Planets in the Solar System

The Solar System we live in consists of the Sun and nine planets. Our Earth is also one of the planets in the solar family. There is no light on these planets. They appear bright only because they reflect the Sun’s rays.

The planets revolve around the Sun, but their speeds are all different. The path a planet follows while revolving around the Sun is called an orbit. Every planet has an orbit.

THE SUN

It is one of the millions of stars in the vast emptiness of space. It is the closest star to Earth (149.5 million kilometers). It is no different from a giant atomic furnace. It continuously converts hydrogen gas into helium gas, producing light, heat, and energy. Resembling a ball made of hot gases, the temperature is around 16–20 million degrees at its center, 6,000 degrees on its surface, and 1.5 million degrees in the outer sections of the corona. The Sun’s rays travel at a speed of 300 thousand kilometers per second and reach our Earth in 8 minutes.

MERCURY

It is the smallest, fastest, and closest planet to the Sun (a distance of 58 million kilometers). This planet completes one full orbit around the Sun in 88 days. One side of Mercury is always facing the Sun. This side resembles a desert made of fire. The temperature is constantly above 400 degrees. The side not facing the Sun is very cold and dark. There is a very thin layer of atmosphere around the planet. No living creatures can survive here.

VENUS

It is 158 million kilometers away from the Sun. It is the brightest planet after the Sun and the Moon. It completes its orbit around the Sun in 225 days. Its rotation speed is 35 kilometers per second. It rotates around its own axis in 30 days. It is slightly smaller than our Earth. Some astronomers suggest that living beings exist on Venus. However, we cannot see the surface of Venus due to the thick dust clouds covering it. The diameter of Venus is 12,300 kilometers.

EARTH

We call the planet we live on Earth. It completes its orbit around the Sun, which is 149 million kilometers away, in 365 days (one year). It completes its rotation around its own axis in 24 hours (one day). Earth completes its orbit around the Sun at a speed of 29.8 kilometers per second. Earth’s satellite is the Moon.

MARS

Mars is the easiest planet to see from Earth. It is 56 million kilometers away from Earth and 226 million kilometers away from the Sun. It completes its orbit around the Sun in 687 days at a speed of 24 kilometers per second. Its atmosphere is very thin. It is not believed that humans or animals can live on Mars. However, it is believed that plants can grow here. Mars has two small satellites. These are Phobos and Deimos.

ASTEROIDS

Asteroids, or minor planets, fill the 563 million-kilometer void between Mars and Jupiter. More than two thousand asteroids have been identified to date. Ceres, the largest of them, has a diameter of 770 kilometers. The smallest ones are merely piles of rock 4–5 kilometers in size. There is no air or life on them.

JUPITER

Jupiter is the giant of the Solar System. It is 1,300 times larger than Earth. It is 779 million kilometers away from the Sun. It completes one rotation around its own axis in 10 hours. It can only complete its orbit around the Sun in 11 years. Jupiter is a very cold place. The temperature here is 130 degrees below zero ($-130^\circ\text{C}$). It has 12 satellites. Four of them can be easily seen with a small telescope. Ganymede, the largest, has a diameter of 5 thousand kilometers.

SATURN

It is the second largest planet in the Solar System. It has a speed of 9.6 kilometers per second. It completes its orbit around the Sun, which is 1,428 million kilometers away, in 29 years. Its rotation around its own axis takes 10 hours and 15 minutes. The temperature on this planet is 140 degrees below zero ($-140^\circ\text{C}$). It has nine satellites. Of these, Titan is larger than the Moon. Its most important feature is its bright rings, which are made up of small satellites. There are three of these rings.

URANUS

The planet Uranus was identified in 1781 by the astronomer William Herschel using a hand-made telescope. Uranus is one of the third largest planets in the Solar System. Its diameter is 53,000 kilometers. It is 2,842 million kilometers away from the Sun. It rotates around its own axis in 10 hours and 40 minutes. It completes its orbit around the Sun in 84 years, traveling at a speed of 6.8 kilometers per second. It has five satellites.

NEPTUNE

The planet Neptune is the fourth largest in size. It completes its orbit around the Sun, which is 4,501 million kilometers away, in 165 years. It rotates around its own axis in 15.5 hours. The average temperature is 200 degrees below zero ($-200^\circ\text{C}$). It has two satellites.

PLUTO

Pluto was discovered in 1930. It is the planet farthest from the Sun (5,919 million kilometers). Because of this, it can only complete its orbit around the Sun in 248 years.

It is slightly larger than Mercury. The temperature on Pluto is thought to be approximately 230 degrees below zero ($-230^\circ\text{C}$).

Pluto is the least understood planet in the Solar System.