Space

• What is gravity?

  Attraction between all objects with mass
• What is the unit of measurement for gravity?

  Newton/kg
• How does Earth's gravitational field affect objects?

  It exerts a force on objects in the field
• Why do planets closer to the Sun travel faster?

  Due to the stronger gravitational force from the Sun
• What happens to the gravitational force as distance increases?

  The force weakens as distance increases
• What do field lines indicate about gravitational force?

  They point towards the center
• What does it mean when field lines are further apart?

  It indicates a weaker gravitational force
• What does it mean when field lines are closer together?

  It indicates a stronger gravitational force
• What is the gravitational force like close to Earth's surface?

  Field lines are parallel and force is the same
• What does Newton's 1st Law of Motion state?

  An object will keep doing what it is doing unless a force is applied
• What is a polar orbit?

  A lower orbit passing over different Earth parts
• Why are polar orbits useful for satellites?

  They allow observation of different Earth areas
• What is a geostationary orbit?

  Orbit at 36,000 km taking 24 hours
• What is the main use of geostationary satellites?

  Communication satellites that stay in one place
• How do communication satellites work?

  They transmit signals between dishes and satellites
• What is the purpose of weather satellites?

  Often put in geostationary orbit
• What do Earth observation satellites provide?

  A detailed picture of Earth's surface
• What is the function of military satellites?

  Used for spying
• How do navigation satellites assist users?

  They provide GPS for ships, cars, and planes
• What do astronomical satellites do?

  Take sharper photographs outside Earth's atmosphere
• What is the tilt angle of the Earth?

  23.5°
• How does the Earth's tilt affect seasons?

  Causes longer days and warmer weather in summer
• Why does the sun appear lower in winter?

  Due to the Earth's tilt and position
• How many galaxies are in the universe?

  At least a billion
• What is our sun's relationship to other stars?

  It is one of many millions in a galaxy
• How far apart are stars in a galaxy compared to planets?

  Stars are millions of times further apart than planets
• How far apart are galaxies compared to stars?

  Galaxies are millions of times further apart than stars
• What is a light year?

  The distance light can travel in one year
• What was the sun made of when it was born?

  100% hydrogen
• What process does the sun undergo to release energy?

  Fusion
• What is nuclear fusion in main sequence stars?

  Joining two hydrogen nuclei to form helium
• What happens when two hydrogen atoms come together?

  They repel due to electrostatic force
• What is required for hydrogen nuclei to fuse together?

  A massive force to allow fusion
• What temperature is needed for fusion to occur?

  15,000,000 °C
• What is the life cycle of a star?

  • Nebula: Cloud of dust & gas
  • Protostar: Contracted part of nebula
  • Main sequence star: Stable phase of fusion
  • Red giant: Expands and cools
  • Red super giant: Fuses heavier elements
  • Planetary nebula: Outer layers shed
  • White dwarf: No more core fusion
  • Black dwarf: Final stage of cooling
• What is a nebula?

  A cloud of dust and gas
• What is a protostar?

  Part of the nebula that contracts and spins
• What happens in the red giant phase?

  Outer layer cools and expands, helium fuses
• What occurs in the red super giant phase?

  Helium fuses into carbon and oxygen
• What is a planetary nebula?

  Outer layers are shed, forming a ring shape