๐ŸŽฒ

๐Ÿš€ Inventions and machines ๐Ÿ“ก Communication

Radar

A phased-array radar tracks missiles and satellites with electronically steered beams, sent out from the radar's clock-like face.
A phased-array radar tracks missiles and satellites with electronically steered beams, sent out from the radar's clock-like face.

๐Ÿ“– In short

Radar is an electronic device that detects faraway objects and finds where they are, even in the dark or behind clouds. Radar sends out invisible waves, and if they hit a plane, ship or rain cloud, they bounce back, so it knows where it is.

๐Ÿคฉ Did you know?

  • Radar waves travel at the speed of light, about 300 thousand kilometers per second.
  • Some giant radars have antennas hundreds of meters across.
  • Radar can detect small things like swarms of insects and flocks of birds.
  • The word โ€œradarโ€ is short for an English phrase meaning โ€œradio detection and rangingโ€.

๐Ÿ”Ž Find out more

๐ŸŒŸ Like a bat

Radar works rather like a bat: it sends out a signal and waits for its echo. The time the echo takes to return tells it how far away the object is.

๐Ÿ” At airports

Every airport has a radar that's always turning, so controllers see all nearby planes on a screen and guide them to take off and land safely.

๐Ÿ’ก Weather radar

Weather scientists use radar to see where rain, snow and hail are falling and where storms are moving, so they can warn people.

๐ŸŽฏ At sea and on the road

Ships use radar to see other ships and rocks in fog. And police use a small radar to check how fast cars are going.

๐Ÿ“ธ More pictures

Air traffic control centers rely on radar to track planes and guide them between airports. Radar waves reflected from planes show up as bright dots on a round screen. Each plane's flight path can be followed by watching the dots move.
Air traffic control centers rely on radar to track planes and guide them between airports. Radar waves reflected from planes show up as bright dots on a round screen. Each plane's flight path can be followed by watching the dots move.
Boats and ships use radar to help them navigate, especially to avoid obstacles when they can't see well. Small boats like the tug (right picture) have several radars with moving antennas above the cabin. The drawing (left picture) shows how radar waves pass through thick fog, and the echoes received let sailors find land, rocks and ships hidden in the fog.
Boats and ships use radar to help them navigate, especially to avoid obstacles when they can't see well. Small boats like the tug (right picture) have several radars with moving antennas above the cabin. The drawing (left picture) shows how radar waves pass through thick fog, and the echoes received let sailors find land, rocks and ships hidden in the fog.
Radar is vital to many countries' national security: missile defense radars give early warning of long-range enemy missiles, and air defense radars detect attacking planes. A space detection and tracking system follows satellites around the Earth, and other radars in the northern hemisphere protect against guided missiles.
Radar is vital to many countries' national security: missile defense radars give early warning of long-range enemy missiles, and air defense radars detect attacking planes. A space detection and tracking system follows satellites around the Earth, and other radars in the northern hemisphere protect against guided missiles.

๐Ÿงฉ Test yourself

1 How does radar know where things are?

2 Where do we find radar?

3 Radar waves travel at the speed of light, about ?? thousand kilometers per second.

4 Which picture shows โ€œRadarโ€?

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