1. Many meteorites falling at once
   The creation of meteors
2. Meteors and asteroids colliding
   Meteors falling into bodies of water

A meteor shower is when many meteorites fall from the same point in the sky. The meteorites are usually debris from comets that have passed.

1. Uranus
   Earth
2. Mercury
   Neptune

So far, Earth is the only planet known to sustain life. Earth is the third planet from the Sun and the only planet in our solar system not named after a god.

1. Stars
   The atmosphere
2. Galaxies
   Pluto

The atmosphere can and does destroy many asteroids and meteorites that try to pass through it, although some are large enough to make it to the Earth.

1. Earth
   Venus
2. Saturn
   Mars

Mars is called the Red Planet because of its reddish appearance. Officially, it was named after the Roman god of war.

1. Jupiter
   Earth
2. Mars
   Venus

Jupiter also has a moon called Ganymede that is the largest moon in the solar system. Like Saturn, Jupiter has rings, but they are not as defined.

1. Marc Garneau
   Yelena Kondakova
2. Neil Armstrong
   Richard Mullane

On the Apollo 11 mission, Neil Armstrong became the first person to walk on the moon. Since then 11 other people have walked on the moon, all of them American men.

1. Jupiter
   Mercury
2. Earth
   Venus

Somewhat surprisingly, Mercury is only the second hottest planet, despite being closest in proximity to the Sun.

1. Planets
   Comets
2. The Sun
   The Moon

Comets also have two tails, one made from dust and the other made from plasma.

1. Comets
   The Moon
2. The Sun
   Asteroids

Asteroids form the Asteroid Belt in our solar system. The Asteroid Belt is 1 astronomical unit thick and hangs out between the orbits of Jupiter and Mars.

1. Comet Swift-Tuttle
   Halley's Comet
2. Comet Hyakutake
   Comet Shoemaker-Levy 9

Halley's Comet was first observed in 239 B.C., and it is expected to pass the Earth again in 2061.

1. A star
   A planet
2. A comet
   An asteroid

The Sun is classified as the only star in our solar system, but many other solar systems are known to have two stars.

1. The Sun
   The Moon
2. Mercury
   Earth

The Sun is the largest object in our solar system. It is currently in its "Main Sequence" phase and will transition into its "Red Giant" phase in a few billion years. It will become even larger in this phase.

1. The Oort Cloud
   The Kuiper Cloud
2. Venus
   Nebulas

The Oort Cloud is located far from the Sun and contains many icy objects. It was named after Jan because he had speculated its existence.

1. Venus
   Saturn
2. Jupiter
   Mars

Saturn's rings are very visible, comparatively. Galileo was the first person attributed with observing them, although they were said to be discovered long before his time.

1. Venus
   Earth
2. Saturn
   Neptune

Early astronomers believed that the Earth was the center of the universe. These astronomers did not have the advanced technology that we now use to determine how objects in the universe actually move.

1. Andromeda Galaxy
   The Milky Way
2. Triangulum Galaxy
   Whirlpool Galaxy

Our solar system is located in the Milky Way, a barred spiral galaxy that has two arms. Our solar system is located on Orion's Arm.

1. Comets
   Stars
2. The Moon
   The Dwarf Planets

There are two tidal bulges on the Earth's surface where the water levels change because of the gravitational pull of the Moon.

1. Mars
   Uranus
2. Neptune
   Venus

The temperature on Venus reaches up to 471 degrees Celsius. It is also the second brightest object in our solar system.

1. 58 minutes
   45 minutes
2. 20 minutes
   8 minutes

The light from the sun travels at 300,000 kilometers per second.

1. It bounces back into space.
   The planet explodes.
2. The planet breaks into small pieces.
   It leaves a crater.

When meteoroids, asteroids or comets crash into a planet, they usually leave behind a crater. Most planets have been hit by many of these objects throughout their existence.

1. The Kuiper Belt
   Beside the Sun
2. The Asteroid Belt
   Beside the Earth's moon

Pluto, Makemake and Haumea are located in the Kuiper Belt. Along with these dwarf planets, the belt also has many other objects within it that are made of ice.

1. Uranus
   Venus
2. Mercury
   Jupiter

Even though Uranus is not the farthest planet from our sun, it reaches some of the lowest temperatures. There are several theories about why, but no one knows for certain - yet.

1. A horse
   A dog
2. A raccoon
   A pig

A dog named Laika was the first animal to go into orbit around the Earth. She was a stray dog that was rescued in Russia and went into space on the Sputnik 2 mission. One of her nicknames in the American press was "Muttnik."

1. The Large Planets
   The Giant Group
2. The Gas Giants
   The Far Orbiters

They are referred to as the Gas Giants. These planets are farther away from the Sun and, although they are primarily made up of gases, they do have rocky centers.

1. Ceres
   Pluto
2. Makemake
   Eris

Pluto is the largest dwarf planet in our solar system, although it is smaller than many other objects found there, including some moons.

1. Dark and cool areas on the Sun
   Bright patches of light
2. Debris from the Sun
   The location of the Sun

Sunspots are areas in the Sun's photosphere that are noticeably darker and cooler than other areas.

1. They will become too hot.
   They will explode.
2. They will be consumed by the Sun.
   They will evaporate.

In its Red Giant phase, the Sun will expand and consume the three planets. If Earth happens to survive, it is likely that its orbit would change.

1. Eight
   Seven
2. Ten
   Nine

There are eight planets in our solar system, because Pluto is considered a dwarf planet. There is also talk about an addition of a new planet that scientists are calling "Planet X"...but we have yet to experience a proper sighting before it becomes official.

1. The Hot Planets
   The Terrestrial Planets
2. The Close Planets
   The Land Group

These planets are mostly solid and made of heavy metals; as a group, they're also referred to as the Inner Planets.

1. Retrograde
   Backwards planetary motion
2. Tailspin
   Counter-clockwise planetary spin

When a planet spins backwards, it's said to be in retrograde. There are two planets in the solar system that are in retrograde motion: Uranus and Venus.

1. A dark night
   A solar eclipse
2. A lunar eclipse
   A pass-through

Total solar eclipses can happen about every 1 or 2 years, and they can last up to 7.5 minutes.

1. 5,000
   1,000
2. 12
   5

There are only five planets that are officially classified as dwarf planets. They are Ceres, Makemake, Eris, Haumea and Pluto. Although it is likely that there are thousands more, only these five are officially classified.

1. Pluto
   Eris
2. Ceres
   Haumea

Ceres is the dwarf planet located in the Asteroid Belt. It is the smallest of the dwarf planets and also the closest to the Sun.

1. Jupiter
   Venus
2. Mars
   Earth

A day on Venus lasts for 243 of our days on Earth. Venus takes 224 days to complete an orbit around the sun.

1. Mars
   Saturn
2. Neptune
   Uranus

Triton is the largest moon that orbits Neptune. It even has its own atmosphere, which is only four other moons have.