8 Planets
Written by Abby Cessna
With Pluto demoted to the new class of dwarf planets in 2006, there are now 8 planets in our Solar System: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune.
In addition to being the closest planet to the Sun, Mercury is also the smallest planet due to Pluto’s demotion. This planet has very little atmosphere because its gravity is too little to retain one.
Venus holds the distinction of being both the brightest planet and the hottest planet in our Solar System. Venus is so bright that it is called the Morning and Evening Star. It is the third brightest object in our Solar System next to the Sun and the Moon.
While Earth is no longer the only planet where liquid water is known to exist, it is still the only planet we know that supports life. There is a possibility that even that will change as we learn more about extrasolar planets, and the other planets in our own Solar System.
Mars is often called the Red Planet because of its color, which is cause by rust on the planet’s surface. This planet is surprisingly small with a surface area only 38% of Earth’s surface area and a volume only 15% of our planet’s volume.
The largest and most massive planet in our Solar System, Jupiter's size is often difficult to fathom. You could fit 1321 Earths inside of Jupiter. That is unbelievably large. Jupiter is also one of four gas giants – also called Jovian planets – in our Solar System. The other three are Saturn, Uranus, and Neptune. As a gas giant, Jupiter has no solid surface. It is composed mostly of gas with a liquid core of heavy metals.
While Saturn is famous for its incredible planetary ring system, there are a number of other interesting facts about the planet. Saturn has at least 60 moons orbiting it. The largest moon, Titan, is the second biggest moon in our Solar System.
Uranus and Neptune are both blue due to the methane in their atmospheres. Uranus was discovered in 1781 by the famous astronomer Sir William Herschel and is only visible with the aid of a telescope. Uranus has quite large rings, which are made of mostly icy particles.
Although we know Neptune was discovered in 1846, there is some dispute as to whether John Couch Adams or Urbain Le Verrier deserves credit for calculating the location of the planet. Some people give them joint credit. Neptune has the fastest winds of any planet; they can reach more than 2100 kilometers per hour. Considering the highest wind speed ever recorded on Earthwas around 370 kilometers per hour, Neptune’s normal winds would make any tornado on Earth seem like a light breeze.
Universe Today has many articles on the planets including order of the planets and an overview of the Solar System.
For more information, check out facts about the eight planets and the inner and outer planets.
Astronomy Cast has an episode on each planet including Mercury.
Filed under: Astronomy
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