Astronomy

• What is the formula for weight in physics?

  W = mg
• What does the variable W represent in the formula W = mg?

  Weight in Newtons (N)
• How does the value of g affect the weight of an object?

  The greater the value of g, the greater the weight of the object.
• What is the relationship between the mass of a planet and the value of g on that planet?

  The greater the mass of the planet, the greater the value of g on that planet.
• Why does more mass result in a stronger gravitational pull?

  More mass leads to a stronger gravitational pull, resulting in a higher value of gravitational acceleration.
• What are the main components of our Solar System?

  • The Sun
  • Eight planets
  • Natural satellites (e.g., the Moon)
  • Dwarf planets (e.g., Pluto, Ceres)
  • Asteroids and comets

  
• List the eight planets in our Solar System.

  Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune
• What mnemonic can help remember the order of the planets in our Solar System?

  My Very Early Morning Jam Sandwich Usually Nauseates
• How do the sizes of planets differ in terms of composition?

  Smaller planets are primarily made of rock, while larger planets are primarily made of gas.
• What is the orbital plane of the planets in our Solar System?

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

  Larger planets have strong gravitational fields that attract debris, forming rings.
• What were the key features of the geocentric model of the Solar System?

  • Earth was at the center
  • Planets, the Moon, and the Sun orbited Earth
  • Everything orbited in perfect circles
  • Fixed background of stars

  
• What were the key features of the heliocentric model of the Solar System?

  • Sun is at the center
  • Mars' retrograde motion as evidence
  • Galileo's observations of moons orbiting Jupiter
  • Kepler's discovery of elliptical orbits

  
• What is retrograde motion in astronomy?

  It is the apparent reversal of a planet's direction in the sky due to the relative motion of Earth and the planet.
• How did Galileo's observations contribute to the heliocentric model?

  Galileo observed moons orbiting Jupiter, showing that not everything orbited the Earth.
• What did Kepler discover about planetary orbits?

  Kepler showed that planets orbit in ellipses, not circles.
• What causes a planet to change direction while orbiting the sun?

  The gravitational force causes the planet to change direction constantly.
• How does the speed of a planet change as it orbits the sun?

  The speed of the planet remains constant while its velocity changes due to direction change.
• What happens to a planet's orbital speed if it moves closer to the sun?

  The orbital speed of the planet increases as it moves closer to the sun.
• What does red shift indicate about galaxies moving away from Earth?

  Red shift indicates that galaxies are moving away from Earth, suggesting an expanding universe.
• What does the emission spectrum show in relation to red shift?

  The emission spectrum shows black absorption lines shifted towards the red end, indicating red shift.
• How does the distance from Earth affect red shift?

  The red shift increases as the distance from Earth increases.
• How can the expansion of the universe be visualized using a balloon analogy?

  • Imagine the universe as an un-stretched balloon with galaxies on its surface.
  • As the balloon expands, the distance between galaxies also expands.
  • Light from a galaxy is red-shifted as it moves away from us.
• What does the Cosmic Microwave Background (CMB) radiation indicate?

  CMB indicates that the hot young universe has cooled and expanded since its formation.
• What does the red shift evidence suggest about the Big Bang?

  Red shift suggests that the universe is expanding and must have originated from a single point.
• What are the key pieces of evidence for the Big Bang theory?

  • Red Shift: Indicates universe expansion.
  • CMB: Cosmic Microwave Background radiation shows the universe has cooled and expanded.
• What does the Steady State Theory propose about the universe?

  It proposes that as the universe expands, matter is constantly created, maintaining a constant density of matter.
• What evidence contradicts the Steady State Theory?

  Different stars present at different eras of the universe show that the universe has evolved, contradicting the theory.

  
• Why does the Steady State Theory not account for CMB?

  Because CMB indicates that the universe has cooled and expanded since its hot, young state.
• What is the life cycle of a star?

  1. Dust and gas cloud forms nebulae.

  2. Gravitational attraction draws particles together.

  3. Temperature and pressure increase.

  4. Fusion occurs, forming helium and releasing energy.

  5. Equilibrium forms, and a star is born.

  6. Star runs out of gas and collapses.

  7. Depending on size, it may become a supernova, neutron star, or black hole.

  
• What happens when a massive star runs out of gas to fuse?

  The star collapses, increasing pressure and temperature, allowing heavier elements to fuse, leading to a supernova.
• What occurs when a normal-sized star runs out of gas to fuse?

  The star swells into a red giant, then contracts and cools into a white dwarf after fusion reactions cease.
• What are the methods used to observe the universe?

  • Use any wavelength in the EM spectrum.
  • X-rays, Gamma, UV require telescopes outside the atmosphere.
  • Evolution from refracting to reflecting telescopes.
  • Technological advances allow measurement of other EM spectrum parts.
• What are artificial satellites?

  Man-made satellites sent into space for purposes such as satellite imaging and communications.
• What does the Big Bang Theory suggest about the universe?

  The universe has expanded from an initially very small, hot, and dense point.
• What are circular orbits and what provides the force for them?

  Circular orbits are paths that satellites or planets travel in, with gravity providing the required force.
• What does CMBR stand for and what is it?

  CMBR stands for Cosmic Microwave Background Radiation, which is electromagnetic radiation found in small quantities around us.
• What is a main sequence star?

  A main sequence star is in a stable state where gravitational forces and pressure are balanced.