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Energy from the Sun

Energy and power · level 1, lesson 3 of 6

A question to start

On a sunny day, a dark car gets hot inside. Plants on a windowsill lean towards the light. What does sunlight bring with it?

The idea

Sunlight carries energy from the Sun to us. That energy:

  • warms things up: the ground, the sea, the air, and you on a beach;
  • makes plants grow: leaves catch sunlight and use its energy to make food;
  • can be turned into electricity by solar panels.

The Sun is a giant ball of very hot gas, far bigger than the Earth. It has been shining for billions of years.

the SunEarthMarsweaker

On Mars, sunlight is less than half as strong as on Earth, because Mars is farther from the Sun. A solar panel there makes less than half as much electricity as the same panel in sunny weather on Earth. And when dust storms fill the sky, even less light gets through.

Worked examples

1. A black T-shirt. On a sunny day, a black T-shirt gets hotter than a white one. Dark colours soak up more of the Sun's energy.

2. A solar calculator. It has a small solar panel. Cover the panel with your thumb in a dim room, and the screen fades.

3. Mars rovers with panels. The rovers Spirit and Opportunity ran on solar panels. Dust settling on the panels made them weaker, until gusts of wind blew it off again.

Try it

  1. Name two things the Sun's energy does on Earth.
  2. What do plants use sunlight for?
  3. Is sunlight on Mars stronger or weaker than on Earth? Why?
  4. Why would a dust storm be bad news for a solar-powered rover?
Answers
  1. For example: warms things, makes plants grow, makes electricity in solar panels.
  2. To make their food, so they can grow.
  3. Weaker, less than half as strong, because Mars is farther from the Sun.
  4. The dust blocks the sunlight, so the panels make less electricity.

Common mistake

"It is colder on Mars because the Sun is smaller there." It is the same Sun. Mars is farther away, so the light is spread out more and less of it falls on each patch of ground.

Where it leads