Telescopes

 

Observe and discuss that there are more stars in the sky than anyone can easily count and that they are not scattered evenly in the sky. Investigate how magnifiers make things appear bigger and help people see things they could not see without them.

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Look up at the night sky.

You can see hundreds of stars.

There are too many to count.

Most of these points of light are stars like our Sun.

A few are planets.

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Planets are within our solar system.

They orbit the Sun like the Earth.

Compared to stars, planets are close.

The stars are very, very far away.

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Planets do not produce their own light.

We see planets because they reflect light.

Stars produce their own light.

Some stars are bigger than our Sun.

Some stars are smaller.

Our Sun is an average size star.

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Why does the Sun look so big?

Objects that are close look large.

Objects that are further away look smaller.

The Sun looks big because it is close.

Light is the fastest thing in the universe.

Even light can take many years to travel from a star.

Light from the Sun takes less than ten minutes to get to Earth.

When you look at stars, you look into the past.

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Scientists use telescopes to study the night sky.

Telescopes do not make stars look bigger.

They are too far away.

Instead, they allow more light to be collected.

Telescopes let us see more stars.

Even with a telescope, stars are only points of light.

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Galileo built the first telescope in 1608.

His first telescope used a lens.

Lenses bend, or refract, light.

Many people still use this type of telescope.

They help us see close objects better.

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You can see the surface of the Moon.

You can see Saturn’s rings.

Are planets close to us? 

Compared to stars, they are close.

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Newer telescopes use mirrors.

Mirrors allow more light to be collected.

This helps us see more stars.

Most scientists use telescopes with mirrors.

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Large telescopes are placed on mountain tops.

Why do you think that is?

It is because Earth’s atmosphere distorts light.

On a high mountain there is less air to look through.

Can you think of a better place to put a telescope?

Telescopes on top of Mauna Kea in Hawaii.

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What is higher than a mountain?

Some telescopes are in outer space.

In space there is no distortion.

The Hubble Space Telescope has been in orbit for more than

20 years.

It sends back very clear images.

The Hubble helps scientists find answers to questions.

(a) The Hubble Space Telescope orbits Earth at an altitude of 589 km (366 mi). It collects data in visible, infrared, and ultraviolet wavelengths. (b) This starburst cluster is one of the many fantastic images taken by the HST over the past two decades.

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