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PHYSICS · Stage 7 · Chapter 5: The Earth in Space

Physics 5.10 Chapter 5 Review: The Earth in Space

5 min read 5 parts Lesson 10 of 11

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Physics 5.10 Chapter 5 Review: The Earth in Space — Alhussan International Academy — Physics (Stages 7–9) notes: Summarise the Earth's spin and orbit, distances in the Solar System, models of the Universe and the use of planetary data.Spin — The Earth spins on its axis once every…

  • Objects seen from Earth
  • Large distances
  • Astronomy and experiments
  • Heliocentric model
  • Telescope evidence
  • Atmospheres

Part 1 of 5Spin, orbit and the seasons

  • Spin — The Earth spins on its axis once every 24 hours, causing day and night.
    • The Sun does not orbit the Earth once a day.
  • Orbit — The Earth orbits the Sun once in about 365 days, which is one year.
  • Seasons — The tilt of the Earth's axis (23.5 degrees) causes the seasons.

Part 2 of 5Objects and distances in the Solar System

  • Objects seen from Earth — With the naked eye or a telescope we see the Sun, the Moon, planets, stars, comets, meteors and artificial satellites.
  • Large distances — Mercury is about 60 million km from the Sun and the Earth is about 150 million km from the Sun.
    • The Earth is 150 ÷ 602.5 times further from the Sun than Mercury.
    • The Earth is 150 − 6090 million km further away.
  • Pattern — Planets nearer the Sun are generally hotter and have shorter orbit times.

Part 3 of 5Geocentric and heliocentric models

  • Astronomy and experiments — Astronomers cannot do experiments on the Universe, so they make observations and develop explanations to account for them.
  • Heliocentric model — The Sun is at the centre and the planets orbit it.
    • It explains the apparent backward motion of planets more simply than the geocentric model.
    • It also explains the phases of Venus.
  • Telescope evidence — Galileo's observations of Jupiter's moons and sunspots helped the heliocentric model replace the geocentric model.

Part 4 of 5Using data about planets

  • SourcesData from a science book is secondary data and should be checked against other sources.
  • ComparingCompare planets' mass, distance from the Sun and temperature to look for patterns.
  • AtmospheresThe atmospheres of the outer planets differ from those of the inner planets.
  • TestingExplanations should be tested against more evidence.

Part 5 of 5Key facts in a table

TopicKey fact
Day and nightThe Earth spins once every 24 hours
SeasonsAxis tilted by 23.5 degrees; the Earth orbits the Sun in 365 days
MoonReflects sunlight; its phases and eclipses result from its orbit
Solar SystemEight planets, dwarf planets, asteroids and comets held by gravity
ModelsThe heliocentric model explains planet motion more simply than the geocentric model

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