The Planets in our Solar System
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Mercury
Mercury is the closest planet to our Sun, at just 58 million km (36 million miles) or 0.39 Astronomical Unit (AU) out. But despite its reputation for being sun-baked and molten, it is not the hottest planet in our Solar System.
Mercury is also the smallest planet in our Solar System, and is also smaller than its largest moon (Ganymede, which orbits Jupiter). And being equivalent in size to 0.38 Earths, it is just slightly larger than the Earth’s own Moon.
Mercury Facts Diameter Mass Year Length Day Length Moons Temperature Gravity Note 4,879 km 3.30 x 10^23 kg 87.97 Days 59 Days Zero -173 to 427 °C 38% of Earth -
Venus
Venus is often called Earth’s “sister planet,” as it is just a little smaller than Earth. And due to its thick atmosphere and proximity to the Sun, it is the Solar System's hottest planet, with temperatures reaching up to a scorching 735 K (462 °C).
Venus Facts Diameter Mass Year Length Day Length Moons Temperature Gravity Note 12,104 km 4.87 x 10^24 kg 225 Days 243 Days Zero 462 °C 91% of Earth -
Earth
Our home, and the only planet in our Solar System (that we know of) that actively supports life. It is the third from our Sun, orbiting at one AU.
Earth Facts Diameter Mass Year Length Day Length Moons Temperature Atmosphere 12,760 km 5.97 x 10^24 kg 365 Days 24 Hours One Avg 14 °C Nitrogen & Oxygen -
Mars
Mars is known as “the Red Planet” because of its reddish hue, due to iron oxide. It has volcanoes, valleys, deserts, and polar ice caps similar to Earth.
Mars Facts Diameter Mass Year Length Day Length Moons Temperature Gravity Note 6,787 km 6.42 x 10^23 kg 687 Days 24h 37m Two Avg -55 °C 38% of Earth -
Jupiter
Jupiter is the most massive planet in our Solar System. It is a gas giant primarily composed of hydrogen and helium, with a violent atmosphere.
Jupiter Facts Diameter Mass Year Length Day Length Moons Temperature Gravity Note 142,800 km 1.90 x 10^27 kg 11.9 Years 9.8 Hours 79 -148 °C 253% of Earth -
Saturn
Saturn is famous for its spectacular ring system. It is a gas giant with layers of gaseous material surrounding a solid core.
Saturn Facts Diameter Mass Year Length Day Length Moons Temperature Gravity Note 120,500 km 5.68 x 10^26 kg 29.5 Years 10.7 Hours 62+ -178 °C 107% of Earth -
Uranus
Uranus is an “ice giant” owing to the presence of ammonia and methane. It has a bluish appearance and is the coldest planet in our Solar System.
Uranus Facts Diameter Mass Year Length Day Length Moons Temperature Gravity Note 51,120 km 8.68 x 10^25 kg 84 Years 18 Hours 27 -216 °C 89% of Earth -
Neptune
Neptune is the farthest planet from the Sun. It is an ice giant with a series of moons and faint rings, appearing bright blue due to methane.
Neptune Facts Diameter Mass Year Length Day Length Moons Temperature Gravity Note 49,530 km 1.02 x 10^26 kg 165 Years 16 Hours 14 -214 °C 114% of Earth
Having covered the basics of definition and classification, let’s get talking about those celestial bodies in our Solar System that are still classified as planets (sorry Pluto!). Here is a brief look at the eight planets in our Solar System. Included are quick facts and links so you can find out more about each planet.