GCSE astronomy general revision

• Aristotle believed that everything revolved around the Earth.
• The Egyptians looked for the rising of Sirius for the start of the Nile flooding.
• For Germans, when the crescent moon and Pleides were in East, it was time to plant their crops. When it was in the West, it was time to harvest them.
• Circumpolarity is when a star never sets below the horizon when viewed from a certain latitude.
• An observer’s zenith is the point directly above their head.
• Lunar phase cycle: New moon, waxing crescent, first quarter, waxing gibbous, full moon, waning gibbous, last quarter, waning crescent
• The photosphere is the surface of the sun and has a temperature of 5,800 K
• The chromosphere is the first layer of the Suns atmosphere and its temperature varies from 4000k to 100,000k
• The convection zone’s energy is transported to the photosphere by convection currents of hot plasma.
• Culmination is when a star reaches the observer’s meridian.
• The distance to the moon was calculated with trigonometry combing its angular size with its diameter and distance
• Valleys on the moon are collapsed lava tunnels
• Rotational and orbital periods of the moon are both 27.3 days because the moon is tidally locked with the Earth
• A sidereal month is 27.3 days
• A solar month is 29.5 days
• The moons near side permanently faces the Earth.
• 59% of the moon is visible from Earth over a period of time.
• The moon has an ellipitical orbit.
• The moons orbits faster nearest to Earth, at perigee
• The moon orbits slowest furthest away from Earth at apogee.
• Liberation in longitude causes a wobbling effect.
• The EOT varies because the Earths orbit is elliptical and the plane of the Earth’s equator is tilted to the plane of the ecliptic by 23 1/2 degrees
• The sun moves along the ecliptic due to how the Earth orbits the Sun and is tilted on an axis of 23.5 degrees relative to the celestial equator.
• Solar rotation period: (360 x time difference) / difference in longitude
• Altitude of Polaris = observers latitude
• The azimuth varies from 0 to 360 degrees and determines the horizontal position of an object
• Altitude varies from 0 degrees at an observer’s horizon to 90 degrees at an observers zenith, and determines the vertical position of an object.
• Solar wind is a constant flow of charged particles emitted from the Sun.
• The corona is the outermost part of the Suns atmosphere and is 2 million K
• Epicycles were a theory that there were cycles that the planets orbited and attached to each were their own cycle
• Solar wind can destabalise orbits of satellites and communications to and from planes
• Craters on the moon are created by meteorite impacts and are surrounded by splash lines called rays
• Maria are the large, dark patches seen on the moon and are made of basalt rock rising to the surface after large meteor impacts
• Terrae are the bright areas on the moon that are mountainous, cratered, and made of anorthosite
• The Earth is an oblate spheroid
• The mean diameter of the Earth is 13000 km
• The Earth’s inner divisions go: Inner core, outer core, mantle, crust
• Latitude = how far north or south
• Longitude = how far east or west
• examples of bad things that effect seeing conditions:

  • Sky colour
  • Sky glow/ light pollution
  • Twinkling