Our Solar System

Earth is just one of the many bodies in our solar system. Our Solar System is made up of nine planets, their moons, and our sun. The planets and their moons revolve around, or orbit the sun.

The Sun contains around 98% of all the material in the Solar System. The larger an object is, the more gravity it has.

Because the Sun is so large, its powerful gravity attracts all the other objects in the Solar System towards it. At the same time, these objects, which are moving very rapidly, try to fly away from the Sun, outward into the emptiness of outer space. Balanced between flying towards the Sun, and escaping into space, they spend eternity orbiting around the Sun.

Below shows an idea of how each planets orbits around the sun.

These nine planets are grouped in many different ways. Two easy groupings are:

Composition

Rocky planets: Mercury, Venus, Earth, Mars, Pluto

The rocky planets are mostly made up of rock and metal. These planets are very heavy and move slowly. They also do not have rings and very few moons.

Gas planets: Jupiter, Saturn, Uranus, Neptune

The gas planets are mostly made up of gases (hydrogen and helium). These planets are light for their sizes (just like a big air balloon) and move quickly. They have rings and lots of moons.

Size

Small planets: Mercury, Venus, Earth, Mars, Pluto

The small planets have diameters less than 13000 km across. Mercury and Pluto are sometimes referred to as lesser planets because they are so tiny.

Giant planets: Jupiter, Saturn, Uranus, Neptune

The giant planets have diameters greater than 48000 km. The giant planets are sometimes also referred to as gas giants.

Click the sun below to get a "closer" look at each of the planets.

Memorize the planets in order

Memorize this sentence: "My Very Educated Mother Just Served Us Nine Pies."
Switch the first letter of each word for the first letter of each planet.
Remember that Mercury is small and fast so it is the FIRST of the two "M" planets.
- My = Mercury
- Very = Venus
- Educated = Earth
- Mother = Mars
- Just = Jupiter
- Served = Saturn
- Us = Uranus
- Nine = Neptune
- Pies = Pluto
Use any fun mnemonic that makes sense to you. You might prefer something like, "Mercury's Volcanoes Erupt Mulberry Jam Sandwiches Under Normal Pace" or "My Very Easy Method Just Speeds Up Name Pronouncing."
Make your mnemonics fun and you will remember them better than you will with mundane ones.

The astronomers have demoted Pluto so there are now only eight planets; Pluto is no longer officially a planet. Now they're calling it a "dwarf planet". Well, it's certainly a dwarf. But planet or not, it's still out there and we can still try to find out what it's made of and how it got there.

Try this!

During an evening, check outside for a full moon. If you see a full moon, take a quarter and go outside. Hold your quarter up (between your thumb and finger) towards the moon and close one eye. By moving your arm to and from your nose, try to "cover up" the moon with your quarter. Even though the quarter is much smaller than the moon, you can succeed in covering it up! This is similar to how the Moon covers up the Sun. The Moon is much smaller than the Sun, but the Moon can cover up the Sun given at the right distance and angle.

Look for Venus! Venus is usually visible with the naked eye. Though it's not correct to call it so, Venus is sometimes called the "morning star" or the "evening star." It is by far the brightest "star" in the sky.

Solar System Riddles

I am the hottest body in the solar system. I keep everyone warm. Who am I? ____________
I am the planet between Venus and Mars. I am the 3rd planet from the sun. Who am I?____________
I am made of gas. I have a ring around me. I am the 8th planet from the sun. Who am I? ______________
I am the 5th planet from the sun. I am almost entirely made out of gas. Who am I? ______________
I am the second planet from the sun. I am very hot. Who am I? _______________
I am the 7th planet from the sun and the planet before Neptune. Who am I ? _______________