The Planets of our Solar System

The Milky Way Galaxy contains an estimated minimum of 100 billion planets, most of which remain unknown to us. However, there are a limited number of planets within our Solar System that we have been able to study in detail.

Our solar system is home to eight planets. Mercury, Venus, Earth, and Mars are terrestrial planets. Jupiter, Saturn, Uranus, and Neptune are the gas giants.

The difference between terrestrial and gas giant planets is size, composition, and the number of moons. There are also celestial bodies orbiting our Sun that are not officially classified planets, such as the dwarf planets Pluto, Eris, Haumea, Makemake, and Ceres. This article will take a more in-depth look at the eight official planets that make up our solar system, plus one that many of us remember as an official planet.

Mercury: The Closest Planet to the Sun

Mercury is the closest planet to the Sun and orbits in just 88 Earth days; and it is smaller than any other planet in our solar system and has no rings or moons. When it comes to Mercury's atmosphere, the most common elements are:

• Oxygen,
• Sodium,
• Hydrogen, 
• Helium, and
• Potassium.

Mercury is the closest planet to the Sun, and it has a diameter of 3,031 miles (4,878 kilometers). Mercury is a terrestrial or solid, rocky planet with a surface covered in craters. If you were to stand on the surface of Mercury, the Sun would appear three times as large as it does when viewed from Earth, and it would rise and set approximately every 176 Earth days. Unfortunately, you wouldn’t be able to stand on Mercury’s surface, as the average temperature is approximately 354 degrees Fahrenheit or 178 degrees Celsius.

Venus: The Hottest Planet

Venus is the second closest planet to the Sun at 67,681,795 miles away. Its diameter is 7,521 miles (12,104 kilometers), only slightly smaller than Earth. Venus has no moons and also no rings, and 96% of the atmosphere is made up of carbon dioxide with clouds of sulfuric acid. Though it is the second planet from the Sun, the surface temperature on Venus can reach 471 degrees Celsius (880 degrees Fahrenheit), hot enough to melt lead. The pressure on the surface of Venus is also 90 times that of Earth’s, making it the hottest planet in our solar system.

Earth: Our Home Planet

Earth is the third planet from the Sun and is the only planet known to support life. It has one moon, and its diameter is 7,926 miles (12,756 kilometers). 71% of the surface is covered in water. The atmosphere contains 21% oxygen. Life on Earth is impossible without liquid water, which is why Earth is sometimes called the "blue planet." Our planet also has an abundance of other resources like air, soil, and minerals. Most of us are familiar with Earth, but some little-known facts are that it is the fifth-largest planet in our solar system, and Earth is the only planet not named after a god.

The surface of Mars is covered in dust and rocks. The planet also has the largest volcano in our solar system, Olympus Mons. The temperature on Mars can range from -133 degrees Celsius (-207 degrees Fahrenheit) to 20 degrees Celsius (68 degrees Fahrenheit). Mars is considered similar in composition to Earth's mantle.

Mars: The Red Planet

Mars is one of the most explored planets other than Earth. In fact, there are currently two rovers, Opportunity and Curiosity, exploring the Martian surface.

Mars is the fourth planet from the Sun. It has two moons, Phobos and Deimos, and its diameter is 4,217 miles (6,792 kilometers). The atmosphere consists of:

• Carbon dioxide,
• Molecular nitrogen,
• Carbon monoxide
• Argon, and
• Traces of molecular oxygen.

The surface of Mars is covered in dust and rocks. The planet also has the largest volcano in our solar system, Olympus Mons. The temperature on Mars can range from -133 degrees Celsius (-207 degrees Fahrenheit) to 20 degrees Celsius (68 degrees Fahrenheit). Mars is considered similar in composition to Earth's mantle.

Jupiter: The Largest Planet

Jupiter is the fifth planet from the Sun and is the largest planet in our solar system. It has 53 official moons and another 23 that are awaiting official names—combined, that's a total of 79 moons. Jupiter has a diameter of 86,881 miles (139,822 kilometers). The atmosphere is made up of:

• Hydrogen
• Helium, and
• A small amount of methane and ammonia

Jupiter's large size means it has a very strong gravitational pull. This makes it difficult for spacecraft to orbit Jupiter and even harder to enter the atmosphere, but that isn't the only issue with exploring Jupiter.

As a gas giant, Jupiter has a thick atmosphere made up of hydrogen, helium, and lesser amounts of methane and ammonia, and no true surface. The temperature in the clouds of Jupiter can range from -145 degrees Celsius (-234 degrees Fahrenheit) to -108 degrees Celsius (-162 degrees Fahrenheit).

Saturn: The Planet with Rings

Saturn is the sixth planet from the Sun and is best known for its rings. It has 82 moons and a diameter of 74,926 miles (120,536 kilometers). The atmosphere is made up of hydrogen and helium.

Saturn is the second-largest planet in our solar system and is one of four with a ring system. Saturn's ring system is the largest and most visible of the four. The rings are made up of pieces of ice and rock ranging in size from a grain of sand to a house. The average temperature on Saturn is around -220 F (-140 C)

Uranus: The Light Blue Planet

Uranus is the seventh planet from the Sun. It has 27 moons and a diameter of 31,518 miles (50,724 kilometers). The atmosphere is made up of hydrogen, helium, and methane.

Uranus is often referred to as the "ice giant" because it is mostly made up of hydrogen, helium, and methane ice. The temperature on Uranus is an average of -213 degrees Celsius (-353 degrees Fahrenheit).

Neptune: The Blue Planet

Neptune is the eighth and farthest planet from the Sun. It has 14 moons and a diameter of 30,775 miles (49,532 kilometers). The atmosphere consists of hydrogen, helium, and methane. Neptune is very similar to Uranus. It is also an "ice giant" with a surface made of hydrogen, helium, and methane ice. The average temperature on Neptune is around -225 degrees Celsius (-373 degrees Fahrenheit)

Pluto: The Reclassified "Dwarf Planet"

Pluto was once the official ninth and final planet from the Sun. Pluto was reclassified as a "dwarf planet" in 2006. This is because Pluto is much smaller than the other planets and its orbit around the Sun is very different from most planets. In fact, it takes 248 Earth years for Pluto to make one trip around the Sun. Pluto has five moons and a diameter of 1,473 miles (2,370 kilometers). The atmosphere consists of nitrogen, methane, and carbon monoxide. Additional dwarf planets in our solar system include Ceres, Haumea, Makemake, and Eris. These dwarf planets are all much smaller than Pluto and have very different orbits.

Conclusion

Our solar system has eight planets: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune. Once our solar system's ninth planet, Pluto was reclassified as a "dwarf planet" in 2006. Each of our solar system's planets has its own unique set of characteristics that make it interesting and worth learning about, including its size, atmosphere, temperature, and moons. So take some time to learn about all the planets in our solar system!