P: space

• What is the central star of our solar system?

  The Sun

  
• What does it mean that the solar system is heliocentric?

  It means that the Sun is at the center of the solar system.

  
• Name two dwarf planets that orbit the Sun.

  Pluto and Ceres
• What other celestial bodies are found in our solar system besides planets and dwarf planets?

  Asteroids and comets
• How is our solar system positioned within the Milky Way galaxy?

  It is a small part of the Milky Way galaxy.

  
• What is the mnemonic to remember the order of the planets in our solar system?

  • My Very Early Morning Jam Sandwich Usually Nauseates (people)
• What are the primary compositions of smaller and larger planets?

  Smaller planets are primarily made of rock, while larger planets are primarily made of gas.
• Do all planets orbit the Sun on the same plane?

  Yes, all planets orbit the Sun on the same plane.
• Do all planets rotate at the same speed?

  No, all planets rotate at different speeds.
• What can cause a planet to rotate in the opposite direction or on a skewed axis?

  Past collisions may throw a planet's axis off balance.
• Why do larger planets have rings?

  Because their strong gravitational field attracts debris.
• What was the initial model of the solar system called?

  The geocentric model.
• What did the geocentric model propose about the arrangement of celestial bodies?

  It proposed that Earth was at the center, with planets, the moon, and the Sun orbiting it.
• What was a key piece of evidence for the heliocentric model?

  Mars' retrograde motion.
• How does Mars' retrograde motion occur?

  Earth orbits the Sun faster than Mars, causing it to appear to reverse direction in the sky.
• What did Galileo's observations of Jupiter's moons demonstrate?

  Not everything orbits the Earth.

  
• What did Kepler discover about planetary orbits?

  He showed that planets orbit in ellipses, not circles.
• What causes a planet to change direction as it orbits the Sun?

  The gravitational force from the Sun.
• How does the velocity of a planet change as it orbits the Sun?

  The velocity is always changing due to the gravitational force causing constant direction change.
• What happens to a planet's speed if it moves closer to the Sun?

  The orbital speed of the planet increases.

  
• What is the first step in the life cycle of a star?

  A dust and gas cloud is present in a galaxy.

  
• What causes the dust and gas cloud to become more concentrated?

  The gravitational attraction between the gas and dust particles draws them together.
• What happens to the temperature and pressure of the cloud as particles get closer together?

  The temperature and pressure increase.
• What occurs when the pressure in the cloud becomes great enough?

  Gas and dust particles are able to fuse together.
• What is produced when hydrogen nuclei fuse together?

  Helium nuclei and a large amount of energy.
• What does the energy released during fusion do in relation to gravitational collapse?


  It opposes the collapsing of the cloud due to gravity.
• What happens when a star runs out of gas to fuse?

  It collapses and is no longer in equilibrium.
• What occurs if a massive star collapses?

  It increases the pressure and temperature of the core, allowing heavier elements to fuse, and may produce a supernova.

  
• What remains after a massive star undergoes a supernova?

  Either a neutron star or a black hole.

  
• What happens to a normal-sized star after it collapses?

  It produces a planetary nebula and eventually a white dwarf.

  
• What does red shift indicate about galaxies?

  They are moving away from Earth.

  
• What does the change in distance of each galaxy's speed indicate?

  It is evidence of an expanding universe.

  
• How can the expansion of the universe be visualized?

  • Imagine the start of the big bang as an un-stretched balloon.
  • Galaxies are on the surface of the balloon.
  • As the universe expands, the balloon expands, increasing the distance between galaxies.
• What happens to the wavelength of light from a galaxy as it moves away from us?

  It becomes red-shifted, appearing to have a longer wavelength.
• How does the frequency of light change as a galaxy moves away from us?

  The frequency appears to decrease.
• What does red shift provide evidence for regarding the Big Bang?

  It shows that the universe is expanding, suggesting it was formed from a single point.
• What does CMB stand for in the context of the Big Bang?

  Cosmic Microwave Background radiation.
• What does the CMB represent about the early universe?

  It shows that the hot young universe has cooled and expanded since its formation.
• Why is the Big Bang model currently accepted?

  It accounts for all the experimental evidence observed in the universe.
• What are two major unknowns in our understanding of the universe?

  Dark mass and dark energy.