GCSE Astronomy — Planet Earth

Led by Eratosthenes of Cyrene

The opening module of Edexcel GCSE Astronomy. Led by Eratosthenes of Cyrene, who measured the Earth's circumference with a stick and a well. The student establishes the geometry of the planet they will spend the rest of the course observing the sky from.

1. Module 1

   Planet Earth

   Led by Eratosthenes of Cyrene

   The question

   What is the shape of the Earth, what does it look like inside, and how is its surface organised so that astronomers anywhere on the planet can describe their position and what they see? The Earth is the platform every observation in this course will be made from. Before the student looks at the sky they need to know where they are standing — the geometry of an oblate spheroid, the four internal divisions inferred from seismic evidence, the coordinate system that makes any place locatable, and the way the atmosphere itself shapes what the naked eye and the telescope can see.

   Outcome

   the student can describe the Earth as an oblate spheroid with a working mean diameter, name and locate its four internal layers and the eight major surface reference lines, read and write any latitude–longitude pair, and explain three atmospheric effects on observation (sky colour, light pollution, twinkling). *(Edexcel 1AS0 Paper 1 — Topic 1, spec points 1.1–1.6)*

   Sub-units

   1. ○ 1.1 Shape and size of the Earth Open this unit → ✓ ↻
   2. ○ 1.2 Internal divisions Open this unit → ✓ ↻
   3. ○ 1.3 Coordinates and surface reference lines Open this unit → ✓ ↻
   4. ○ 1.4 The atmosphere as observing medium Open this unit → ✓ ↻
   Begin the course → Print certificate of completion