Telescopes and lenses
How telescopes and lenses work, the kinds of telescopes, and the history up to SALT and MeerKAT. Read one part at a time and tap “I know this”. Then test yourself in the quiz.
Know it already? Jump straight to the quiz
How a telescope works
| Part | Job |
|---|---|
| Objective lens | The large lens that gathers light |
| Eyepiece | The lens you look through; change it and the magnification changes |
| Mount | Turns slowly to follow the Earth’s rotation |
Stars still look like points, because they are unimaginably far away. The easiest thing to see through a small telescope is the Moon’s craters. A telescope shows distant objects; a microscope shows tiny objects; a magnifying glass makes nearby things bigger.
The history
| Year | Who or what |
|---|---|
| 1608 | Hans Lipperhey, a spectacle maker, makes the first telescope |
| 1609 | Galileo builds his own, stronger telescope and points it at the sky |
| 1610 | Galileo discovers four moons orbiting Jupiter |
| 1668 | Isaac Newton uses a mirror instead of a lens |
| 1930s | Karl Jansky discovers radio waves from space |
| 1990 | Hubble Space Telescope launched |
| 2021 | James Webb Space Telescope looks very deep into space |
Galileo’s discovery changed what people believed: not everything orbits the Earth.
Telescopes in South Africa
- Large telescopes stand on high mountains and in dry places: less air and light get in the way.
- Light pollution from cities hides faint stars.
- A space telescope orbits above the air: no atmosphere gets in the way.
- An observatory is a building that houses telescopes.
Remember this and test yourself
- A telescope gathers light and makes distant things look closer; a larger objective lens gathers more light.
- Refractor: lenses. Reflector: mirrors. Radio telescope: radio waves.
- A convex lens (thicker in the middle) brings light together at the focal point.
- SALT stands at Sutherland; MeerKAT is 64 radio dishes in the Karoo: dry, dark and far from cities.
- Never look at the Sun through a telescope.
Write these points in your book. Read them again the night before the test.
Refractor = light passes through lenses. Reflector = light bounces off mirrors. Radio = listening to the universe.
Important words
First say what the word means, then turn the card over.
Match column A to column B
Tap a word in column A, then its meaning in column B. You can also start in column B.
True or false?
Read the question and the answer. Is the answer right? Tap True or False.
Now the real quiz!
The quiz has many more questions on this topic. Every question shows straight away whether you are right and explains why.
Take the quiz: Telescopes and lenses- Read one part together and ask your child to tell it back in their own words.
- The ticks (“I know this”) are saved on this device only. We never ask for names or emails.
Follows CAPS for Grade 6 Natural Sciences and Technology. Always check your teacher’s notes and textbook too.