What are some discoveries made using infrared telescopes?

In one line

The rule

Infrared telescopes collect and measure infrared radiation (heat energy) from space, revealing objects and details that normal telescopes cannot see.

Infrared radiation is a type of light we cannot see with our eyes, but we can feel as heat.

Let's understand it simply

Imagine you are in a dark room. You cannot see your friend, but if you touch their hand, you feel their warmth. Infrared telescopes work like this—they sense the heat (infrared light) from objects in space, even if those objects are hidden by dust or are too cold to shine in visible light.

Think of a foggy morning in your village. You cannot see the sun, but you can feel its warmth. Infrared telescopes can 'see' through the fog (space dust) and find stars and planets hidden from normal view.

How it works

1. Space and ground-based infrared telescopes collect infrared light using special mirrors and detectors.
2. This light passes through filters that block unwanted wavelengths.
3. The detectors convert the infrared light into electrical signals.
4. Computers turn these signals into images or graphs.
5. Scientists study these images to find hidden stars, planets, and galaxies.
6. Some telescopes are put in space to avoid Earth's heat and atmosphere, which block infrared light.

The story behind it

Infrared light was discovered by William Herschel in 1800 when he used a thermometer to measure heat beyond the red part of sunlight. The first true infrared telescopes were built in the 1960s and 1970s. The launch of the Infrared Astronomical Satellite (IRAS) in 1983 was a turning point—it was the first space telescope to scan the sky in infrared, revealing many new objects.

Where you see it in real life

• Star nurseries: Infrared telescopes like Spitzer and Herschel have found baby stars forming inside thick clouds of dust. Visible light cannot pass through the dust, but infrared can.
• Exoplanets: Telescopes such as Hubble (in infrared mode) and Spitzer have detected planets around other stars by seeing their heat.
• The centre of our galaxy: The Milky Way’s centre is hidden by dust. Infrared telescopes have mapped it, revealing a supermassive black hole.
• Brown dwarfs: These are 'failed stars' that are too cool to shine in visible light. Infrared telescopes have discovered many of them.
• Distant galaxies: Some galaxies are so far away that their light is stretched into the infrared. Telescopes like the James Webb Space Telescope (JWST) can see them.
• Comets and asteroids: Infrared telescopes have studied the heat from comets and asteroids, telling us about their size and what they are made of.

Why it matters

• Sees the invisible: Infrared telescopes let us see things hidden by dust or too cool for visible light.
• Finds new worlds: They help find planets around other stars, a big step in searching for life.
• Studies the early universe: They can look back in time to when the first galaxies formed.
• Helps understand star birth and death: By seeing inside dusty clouds, we learn how stars are born and die.

Worked example

Let’s say a telescope finds a star hidden in dust. Here’s how:

Given: Star is hidden by dust, visible light is blocked
Step 1: Use an infrared telescope to observe the area
Step 2: Infrared light passes through the dust
Step 3: Detector picks up heat from the hidden star
Step 4: Computer makes an image showing the star
Step 5: Scientists confirm a new star has been found

Common mistakes

• Thinking infrared is only for hot things: Even cold objects in space give off infrared light.
• Believing all telescopes can see everything: Normal telescopes cannot see through dust; only infrared can.
• Mixing up infrared and ultraviolet: Infrared is heat (longer wavelength), ultraviolet is beyond violet (shorter wavelength).
• Forgetting about Earth's atmosphere: Most infrared light is blocked by our air, so many infrared telescopes are in space.

Remember it

Infrared telescopes are like night-vision goggles for space—they see the heat and reveal the hidden universe.