Lesson 11.4: Real-World Connection

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At the Edge

What lurks at the edge of our solar system? Quaoar. Quaoar is a large asteroid, or an object that orbits the Sun, which astronomers recently discovered. It is 4 billion miles from Earth and 1 million miles past Pluto.

Quaoar is made of frozen gases and is about half the size of Pluto. In fact, Quaoar is so similar to Pluto that some scientists say it may be evidence that Pluto is not a planet at all.

Those scientists say Pluto may be a large asteroid. They say Pluto and Quaoar may be part of an asteroid belt that encircles the rest of the solar system. They are looking for more asteroids.

Even though astronomers have found a new object in the solar system, this discovery may mean that there is one less planet in the solar system.

Size of Quaoar Compared With Other Space Objects
Earth—8,000 miles across
Earth's moon—2,100 miles across
Pluto—1,400 miles across
Quaoar—800 miles across

Word Wise

asteroid:
An object that orbits the Sun: Asteroids that can pass inside the orbit of Mars are called near-Earth asteroids.

astronomer:
A person who studies astronomy: Astronomers study the planets, moons, stars, and galaxies.

encircle:
To form a circle around: The birds encircle the pond looking for food to eat.

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Activity

Read each sentence. Then fill in the blank with the word that completes the sentence.

  1. Quaoar is blank.
    1. a planet
    2. an asteroid
    3. a moon
  2. Scientists believe that blank may also be an asteroid.
    1. Pluto
    2. Earth
    3. Saturn
  3. Quaoar is made of blank.
    1. meteors
    2. frozen gases
    3. moons
  4. The size of Earth's moon is about blank across.
    1. 8,000 miles
    2. 4,100 miles
    3. 2,100 miles
  5. Quaoar is blank miles from Earth.
    1. 1 million
    2. 4 million
    3. 4 billion

Data Hunt

Our Solar System

The table shows some information about the planets in our solar system and Quaoar. Study the table. Then answer the questions.

Planets and Quaoar Distance from the Sun (miles) Length of Year (Earth Years)
Mercury 36 million one-fifth
Venus 67 million three-fifths
Earth 93 million 1
Mars 142 million 2
Jupiter 484 million 12
Saturn 891 million 29
Uranus 1,785 million 84
Neptune 2,793 million 164
Pluto 3,647 million 248
Quaoar 4 billion 285
  1. Which planet is closest to the Sun? blank
  2. Which planet is almost twice as far from the Sun as Jupiter is? blank
  3. Compared to Mars, how much longer is a day on Jupiter? blank
  4. How far apart are Earth and Venus? blank
  5. How far apart are Pluto and Neptune? blank