Earth

• The Earth


  • Consists of a range of diverse elements, including land, water, and air
  • The right combination of factors, including the earth's atmosphere, air temperatures as well as the presence of water, allows the earth to support life
  • These conditions allow living things to flourish in many of the earth's ecosystems
• Components of the atmosphere

  • Nitrogen 78%
  • Oxygen 21%
  • Argon 0.9%
• Components of the atmosphere on other celestial bodies

  • Venus: Carbon dioxide 95%, Nitrogen 2.6%, Oxygen
  • Moon: No atmosphere present
  • Mars: Carbon dioxide 95%, Nitrogen, Oxygen
• Evolution of Earth


  1. The Earth was formed (4600 mya)

  2. The core and crust of the Earth formed (4500 mya)

  3. The first oceans formed on Earth (4400 mya)

  4. Earth hosted the first life (3850 mya)

  5. The atmosphere of the Earth started to fill with oxygen (1500 mya)

  6. The first animals appeared (700 mya)

  7. The first vertebrates (fish) evolved (530 mya)

  8. The very first land plants appeared (400 mya)

  9. The very first land vertebrates appeared (350 mya)

  10. The first dinosaurs evolved from lizards (225 mya)

  11. Dinosaurs became extinct (65 mya)

  12. Humans have evolved (0.13 mya)
• Geological eras


  • Precambrian (4600 bya - 542 mya)
  • Paleozoic (542 - 250 mya)
  • Mesozoic (250 - 65 mya)
  • Cenozoic (65 mya - present)
• Precambrian


  • Age of Early Life, Continents formed, Modern atmosphere developed, Early life evolved and flourished
• Common Precambrian fossils


  • Stromatolites and similar structures, Microfossils of microorganisms
• Paleozoic


  • Break up of the supercontinent, Formation of another, Plants became widespread, Appearance of fishes and amphibians
• Mesozoic


  • Age of the dinosaurs, Divided into Triassic, Jurassic, and Cretaceous period, Dinosaurs began to extinct, Mammals started to evolve
• Cenozoic


  • Ice Age, Evolution of humans
• Rotation


  Spin on an internal axis
• Revolution


  Movement of one mass around another
• Aphelion is when the Earth is 153.06 million kilometers from the Sun and happens during the month of July
• Perihelion is when Earth is 147 million kilometers from the sun and happens during the month of January
• Lunar phase


  The shape of the directly illuminated section of the Moon as viewed from Earth
• Lunar phase changes


  1. Orbital locations of the Moon around Earth and of Earth around the Sun fluctuate

  2. Gradual change in the lunar phases over a synodic month (about 29.53 days)
• New Moon


  • Illuminated side faces the Sun
  • Night side faces Earth
  • Moon is in the same part of the sky as the Sun
  • Illuminated side is not visible from Earth
• Waxing Crescent


  • Illuminated half of the Moon faces mostly away from Earth
  • Only a tiny portion is visible from Earth
  • Grows larger every day as the Moon's orbit brings the Moon's dayside closer to Earth
  • Moon rises a little later each day
• First Quarter


  • Moon has completed one-quarter of its monthly journey
  • Half of the illuminated side is visible from Earth
  • Moon rises at noon and sets at midnight
  • Excellent viewing in the evening
• Waxing Gibbous


  • Majority of the Moon's dayside is now visible
  • Moon appears brighter in the sky
• Full Moon


  • Whole day portion of the Moon is illuminated
  • Moon is opposite the Sun
  • Moon rises near sunset and sets near sunrise
• Waning Gibbous


  • Illuminated side appears to shrink as the Moon moves out of our line of sight
  • Moon appears later and later each night
• Last Quarter


  • Half of the half of the Moon that is illuminated by the Sun is visible
  • Moon rises around midnight and sets around noon
• Waning Crescent


  • Moon is almost back to the spot in its orbit where its dayside straight faces the Sun
  • Only a thin curve is visible
• Solar eclipse


  • Occurs when the moon is located between the sun and the Earth, they are aligned on the same plane
  • Moon casts a shadow on the Earth, blocking out the sun
• Lunar eclipse


  • Occurs when the Earth is between the sun and the moon, the alignment on the same plane occurs
  • Earth casts a shadow on the moon causing the moon to go dark
  • Also has a penumbra and an umbra
• Tides


  Sea-level rises and falls caused by the combined impact of the Moon's (and, to a lower extent, the Sun's) gravitational forces, in addition to the Earth and Moon orbiting each other