Topic 9, Topic 10, Topic 11

• What is the Capture Theory regarding the formation of the Earth and Moon?


  The Moon was captured by the Earth’s gravitational force.
• What does the Co-accretion Theory propose about the Earth and Moon?


  The Earth and Moon formed together out of the original nebula.
• What is escape velocity?


  It is the velocity required to escape the gravitational pull of a body.
• How does escape velocity differ between the Earth and the Moon?


  You need to travel faster to leave the Earth than to leave the Moon.
• What does the Giant Impact Hypothesis suggest about the Moon's formation?


  A small planet impacted the Earth, and debris cooled and condensed to form the Moon.
• What is the temperature of the chromosphere?


  Up to 100,000K.
• What is the role of the chromosphere in the Sun's atmosphere?


  It surrounds the photosphere and is only visible during an eclipse.
• What is the convective zone of the Sun?


  It is where thermal energy is transported out by rising convection currents of hot plasma.
• What is the temperature range in the convective zone?


  Temperature varies from 2 million K at the bottom to 5800 K at the top.
• Where does fusion occur in the Sun?


  In the core.
• What is the temperature of the Sun's core?


  Around 15 million K.
• What is the temperature of the corona?


  Up to 2 million K.
• When is the corona visible?


  Only during an eclipse.
• What is fusion in the context of the Sun?


  It is the combining of two small nuclei into a larger nucleus, such as hydrogen into helium.
• What conditions are necessary for fusion to occur?


  Extremely high temperature and pressure.
• What are geomagnetic storms?


  They are the effect of the solar wind hitting Earth’s magnetic field, causing electrical surges.
• What does an H-alpha filter do?


  It absorbs all sunlight except a very narrow wavelength range centered on a particular spectral line of Hydrogen (656nm).
• What is the magnetosphere?


  It is the region around the Earth that is dominated by the Earth’s magnetic field.
• Where is the magnetic north pole located?


  Near the Earth’s geographic south pole.
• What is the photosphere?


  It is the “surface” of the Sun that we see, with a temperature of 5800K.
• What is the proton-proton cycle?


  It is a chain of fusion reactions in the Sun converting a single proton into Helium.
• How is energy transferred in the radiative zone?


  Energy is transferred by gamma photons outwards.
• What is solar wind?


  It is the constant flow of charged particles coming out from the Sun.
• What is the speed of solar wind?


  Travelling at around 400 km/s.
• What are sunspots?

  They are cooler, darker areas on the Sun’s photosphere caused by tangled areas of magnetic field.
• What is telescopic projection?


  It is projecting the sun through a telescope onto a screen behind.
• What are the Van Allen Belts?


  Areas where the solar wind has become trapped within our magnetic field.
• What is found in the inner Van Allen Belt?


  It is mostly protons and is around 2000 km from the Earth.
• What is found in the outer Van Allen Belt?


  It is mostly electrons and is around 6000 km from the Earth.
• What is an aperture in a telescope?


  The diameter of the objective lens or mirror that determines the amount of light the telescope receives.
• How does aperture affect telescope performance?


  A larger aperture is needed for viewing dimmer objects.
• What is an asteroid?


  A lump of rock, usually found orbiting the Sun between the orbits of Mars and Jupiter.
• What is an astronomical unit?


  The distance between the Sun and the Earth.
• What is a Cassegrain reflecting telescope?


  It uses a concave primary mirror as the objective, reflecting light onto a secondary mirror.
• What is chromatic aberration?


  It is where colors are separated by the lens, distorting the image colors in refracting telescopes.
• What is a comet?


  A lump of ice and rock that orbits the Sun, often visible with a tail when near Earth.
• Why do comets develop tails?

  Because the solar wind and radiation pressure cause them to partially melt.
• What is a concave lens or mirror?


  A lens or mirror that curves inwards towards the center, like a cave.
• What is a convex lens or mirror?


  A lens or mirror that curves outwards, like a bubble.
• What is a dwarf planet?


  A small planet-like body that is large enough to become spherical but too small to have cleared its orbit of debris.