Stars and Planets

• How did solar system form?

  1. Gravitational forces cause the matter to get closer together creating the sun and planets.
  2. During formation rocks moved close together to sun and formed rocky planets.
  3. Gaseous substances gathered together at distances further away + formed gas planets
• How are planets kept in orbit around the Sun?

  By gravitational forces
• What separates the inner and outer planets?

  The asteroid belt
• What are the two main groups of planets in the solar system?

  Inner rocky planets and outer gaseous planets
• What is the composition of the asteroid belt?

  Rocky material and debris
• What is the primary component of the cloud from which the solar system formed?

  Hydrogen
• What happens to the cloud of dust and gas as it contracts under gravity?

  It becomes compressed and hotter
• What is formed at the center of the spinning cloud?

  A protostar
• What process occurs when the protostar gets hot enough?

  Nuclear fusion
• What is the result of nuclear fusion in the protostar?

  The Sun is born
• Why do denser materials migrate closer to the Sun?

  Due to stronger gravitational pull
• What explains the difference between inner rocky planets and outer gaseous planets?

  Density of materials and gravitational pull
• Name the four inner planets.

  Mars, Mercury, Earth, Venus
• What type of material formed the inner rocky planets?

  Denser non-volatile material
• What are the outer four planets known as?

  Gas giants
• How do the sizes of outer gas giants compare to inner rocky planets?

  They are much larger
• What is the mass range of gas giants compared to rocky planets?

  Gas giants are far more massive
• Why is Pluto classified as a dwarf planet?

  Due to its small mass and irregular orbit
• How many moons does Earth have?

  One moon
• How many confirmed moons does Saturn have?

  53 confirmed moons
• What are moons also referred to as?

  Natural satellites
• What distinguishes comets from asteroids?

  Different compositions and movement characteristics
• What are comets primarily composed of?

  Rock and ice
• What happens to comets as they near the Sun?

  Heat melts the ice and vaporizes it
• What type of orbits do comets have?

  Highly elliptical and irregular orbits
• Where are asteroids mainly found?

  In the asteroid belt
• What can asteroids be remnants of?

  Former planets or collisions in space
• How do the masses of comets and asteroids compare to planets?

  They are far less massive
• What is thought to be at the center of most galaxies?

  A supermassive black hole
• What initiates the birth of a star?

  A cloud of dust and gas
• What happens to the cloud of dust and gas as it becomes denser?

  Temperature and pressure increase
• What occurs when the pressure in the cloud becomes great enough?

  Particles can fuse together
• What is released during nuclear fusion?

  A large amount of energy
• What causes gaseous expansion in a star?

  Heat energy released from fusion
• What establishes equilibrium in a star?

  Balance between fusion and gravitational forces
• How long can a star remain in equilibrium?

  Billions of years
• What happens when a star runs out of gas nuclei?

  Gravitational collapse occurs
• What occurs in massive stars when they begin to collapse?

  They become red supergiants
• What happens when fusion ceases in a massive star?

  An iron core forms and collapses
• What is formed after a massive star explodes in a supernova?

  A neutron star