Astronomy

• Star is a large, glowing ball of gas that generates heat and light through nuclear fusion
• Planets may be rocky, icy, or gaseous in composition
• Observable Universe- is the part we can see within the horizon
• The distance light can travel in one year is 10 trillion kms.
• speed of light is 300,000,000 m/s or 300,000 km/s
• • Formula to calculate how far is a light year: distance= velocity x time
  • How far is a light year? 9,460,000,000,000= 9.46 x 10^12
• The Milky way is one of about 100 billion galaxies
• When it comes to our place in the solar system, which model do we accept today?

  Heliocentric
• When a planet temporarily moves westward in the sky instead of eastward, it is called :

  retrograde motion
• The Renaissance astronomer who wrote the pioneering book that suggested the Earth orbits the sun was:

  Copernicus
• Which planet do not have satellites (moon)?

  Venus
• During the process of differentiation: Heavier materials sink to the centers of molten planets.
• Planets with atmosphere:

  Earth, Venus, Jupiter, Neptune
• Evidence that helps astronomers sort out how the planets in our solar system formed is?

  Finding circumstellar disks of material around nearby stars.
• The telescope that allowed astronomers to discover most of the planets found in the transit method was called?

  The Kepler mission
• 2 Small moons in the solar system, known since the 19th century, turn out to be captured asteroids; these two moons are?

  Phobos and Deimos around Mars
• Spacecraft that got the closest to the nucleus of Halley's comet and sent back photos of what the nucleus looked like was?

  Giotto
• How do astronomers learn what elements are present in a given star?

  look at the absorption lines in the spectrum