What the Universe is Made of?

• What is anything that orbits a planet called?

  Satellite
• What distinguishes natural satellites from artificial satellites?

  Natural satellites aren't man-made
• What is an example of a natural satellite?

  The Moon
• What are artificial satellites used for?

  Communication and orbiting telescopes
• How many planets orbit the sun in our solar system?

  Eight
• What is the central star of our solar system called?

  The Sun
• Name three planets in our solar system.

  Earth, Mars, Jupiter
• What type of orbit do planets have around the sun?

  Slightly elliptical orbit
• What are the two structures mentioned besides planets?

  Asteroids and comets
• What are asteroids primarily made of?

  Rock and metal
• Where are asteroids mainly found?

  In the asteroid belt
• What are comets primarily made of?

  Ice and dust
• How do the orbits of comets differ from those of planets?

  Comets have much more elliptical orbits
• What is the name of our galaxy?

  The Milky Way Galaxy
• What do galaxies consist of?

  Billions of stars
• How does our solar system relate to the Milky Way Galaxy?

  It is a tiny speck in the galaxy
• What holds stars together in a galaxy?

  Gravity
• How do stars in a galaxy move?

  They spin around the middle
• What is the universe mostly filled with?

  Empty space
• What is the relationship between galaxies and the universe?

  The universe is scattered with galaxies
• How do solar systems relate to stars and planets?

  Solar systems consist of a central star and orbiting planets
• What can orbit planets like Earth?

  Satellites
• What is the structure of the solar system?

  • Central star (the Sun)
  • Eight planets: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune
  • Natural satellites (e.g., the Moon)
  • Artificial satellites (e.g., communication satellites)
  • Asteroids (mainly in the asteroid belt)
  • Comets (made of ice and dust)
• What are the key features of galaxies and the universe?

  • Galaxies: collections of billions of stars
  • The Milky Way is our galaxy
  • The universe is mostly empty space
  • Galaxies are scattered throughout the universe