The Solar System contains the Sun, (at least) eight planets and their moons, and many smaller objects such as dwarf planets, asteroids, and comets.

Planets are heavenly bodies that revolve around the Sun in elliptical orbits. Unlike stars, planets do not emit their own light, but reflect it from the Sun.

Planets can be classified in many ways: by their distance from the Sun, by their orbit relative to the orbit of the Earth, by their composition, their size, etc. In this activity we will see how they are classified in relation to the orbit of our planet.

Introduction

You surely know many facts about the Solar System. Here you can further learn with PETeR, for instance, which planets are visible to the naked eye, how we observe them from Earth, how we can calculate their sizes,…

Download here the INTRODUCTION to this Unit: UNIT 1 – Inner and outer planets

Activities

Would you like to put your knowledge into practice? Follow-up Galileo’s footsteps and discover more about the Solar System and the planets with these activities:

Venus

Venus is one of the inner planets and, therefore, has phases similar to those of the Moon. In this activity you will be able to estimate its size and calculate its phases using real images of the planet obtained with the Liverpool Telescope.

• Download the GUIDE of the activity: Unit 1_Activity 1
• Download the images of VENUS you are going to work with
• Download this SPREADSHEET to write down your measurements.
• If you haven’t already done so, download the software (PeterSoft) to view and analyse the images.

Mars

Mars is the closest outer planet to Earth. Both our planet and Mars revolve around the Sun, but they revolve at different velocities and take different times to complete their orbits. With this activity you can see how the apparent size of Mars (as we see it from Earth) changes as we move closer to or further away from the planet.

• • Download the GUIDE of the activity: Unit 1_Activity 2
  • Download the images of MARS you are going to work with.
  • Download this SPREADSHEET to write down your measurements.
  • If you haven’t already done so, download the software (PeterSoft) to view and analyse the images.

Remember you can also obtain your own images of the planets in  “Quiero Observar” and make new measurements and investigations.

Activity data

Concepts: Planets and Exoplanets. Inner and Outer Planets. Phases in the inner planets. Distances in the sky: angles.

Tools to learn to use: Measurement of distances. Scales.

Estimated time: 4 hours.

Authors: Oswaldo González, Nayra Rodríguez, Alfred Rosenberg, Inés Bonet.

Materials for educators:  Teacher Guide.