Biology-Term 4 '23

• The Sun: 91% Hydrogen and 8.9% Helium. It is 15 million degrees Celsius. The fusion of hydrogen and helium is what keeps the sun hot. The sunlight takes 8 minutes to reach Earth.
• The sun consists of 4 layers:

  1. Corona-releases solar and nuclear particles.
  2. Chromosphere-reabsorbs most of the suns energy and produces a red glow.
  3. Photosphere-Emits most of the suns energy.
  4. Core
• Number of moons:

  • Mercury-0
  • Venus-0
  • Earth-1
  • Mars-2
  • Jupiter-63
  • Saturn-62
  • Uranus-27
  • Neptune-13
• Mercury: It takes 88 days to orbit the sun, it rotates once every 59 days. It is 4850 kilometers in diameter. It is 580 degrees C. Its atmosphere consists of oxygen, sodium and hydrogen.
• Venus: Its atmosphere consists of sulfuric acid and carbon dioxide. It is the hottest planet, 630 degrees C. It takes 243 days to orbit the sun but 243 days to revolve around its self.
• Earth: Has a diameter of 12 000km. The atmosphere consists of nitrogen, oxygen and 1% of other gases. 14 degrees C.
• Mars: 6790km in diameter, orbits the sun in 687 days, takes 24.6 hours to revolve around itself. Atmosphere consists of carbon dioxide, -81 degrees C.
• Jupiter: Diameter of 142 000 km, orbits the sun in 4332 days, takes 9hours 56 minutes to revolve around itself. Atmosphere consists of methane, ammonia and water vapor. Temperature ranges from -145 to +145 degrees C.
• Saturn: Diameter of 116 000km, orbits the sun in 10759 days, takes 10hours 39minutes to revolve around itself. Atmosphere consists of methane, ethane and helium. Temperature ranges from -184 to +127 degrees C.
• Uranus: Diameter of 50 000km, orbits the sun in 30687 days, takes 17hours 14minutes to revolve around itself. Atmosphere consists of methane, ethane and helium. Temperature ranges from -224 to +59 degrees C.
• Neptune: Diameter of 49 000km, orbits the sun in 60171 days, takes 16hours 6mins to revolve around itself. Atmosphere consists of methane, ethane and helium. Temperature ranges from -227 to +53 degrees C.
• Oort cloud: Cloud of small, icy objects
• Comet: A large, long-period comet is a ball of ice and dust that sometimes orbits the sun.
• Asteroid: A large rocky body orbiting the sun, average size between planet and meteroid.
• Meteoroid: A small, rocky object that travels through space, between the size of a grain of dust and a small asteroid.
• Meteor: A meteoroid that burns up when it enters Earth's atmosphere.
• Moon: Natural satellite of a planet, formed by accretion of debris left over from formation of the solar system.
• Meteorite: When a meteor reaches Earth's surface it becomes known as a meteorite.
• Dwarf planets: Pluto, Ceres, and Eris.
• • You
  • Earth
  • Solar system
  • Milky way galaxy
  • Galaxies
  • Universe
• Hubble space telescope: 1990s, used to observe distant galaxies, found that the universe is expanding.
• Southern African Large Telescope: SALT is an optical telescope.
• MeerKAT: Radio telescope, picks up weak radio waves.
• Space satellites: Satellites that orbit the Earth and/or other planets.