A tour of the planets: years, gravity and your weight
Visit the eight planets. Find how long a year lasts on each, how long sunlight takes to get there, and what you would weigh, from little Mercury to giant Jupiter.
Core concept
The planets go round the Sun at different distances: the farther a planet, the longer its year; each planet's gravity is different, so the same mass weighs differently
Topic: The Earth and space
The Sun is a star, and eight planets travel round it: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune. A planet's year is the time it takes to go once round the Sun. Planets farther out have farther to go and move more slowly, so their years are longer. Sunlight takes about 8 minutes to reach the Earth, and much longer to reach the outer planets. Each planet pulls things towards it with its own gravity: The pull that makes things fall towards the Earth. All key words. Your mass: How much matter something has, measured in grams or kilograms. It is the same everywhere. All key words (how much matter you are made of) is the same everywhere, but your weight: The pull of gravity on something, measured in newtons. It is less on the Moon. All key words (the pull of gravity on you) is different on every planet: weight = mass × gravity.
What you will learn
- Name the planets in order from the Sun.
- Explain why planets farther from the Sun have longer years.
- Explain the difference between mass and weight.
- Calculate weight on another planet using weight = mass × gravity.
Before you start
- Know that weight is a force measured in newtons (N).
Materials
- A chart of the solar system
Equipment
- A bathroom scale (it shows mass in kg on Earth)
Procedure
- Visit the Earth with a 40 kg mass and record.
- Visit Mars and Jupiter and record both.
- Visit Mercury and record.
- Visit Neptune and record.
How this simulation is simplified
- Distances are average distances from the Sun in astronomical units (AU); 1 AU is the Earth's distance, and light takes 8.3 minutes to cross it.
- Gravity is at each planet's surface (for the giant planets, at the top of the clouds).
- The planets' figures are rounded.