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341

liquid mirror telescope

OLogy Series
tool
card
341

liquid mirror telescope

OLogy Series
tool

Most reflecting telescopes use glass mirrors to focus light from faraway objects, such as stars and galaxies. In a liquid mirror telescope, this mirror is a pool of shiny liquid instead of glass. Someday scientists hope to build a huge liquid mirror telescope at the Moon's South Pole. Since there's no atmosphere to blur the view, astronomers can see clearer and farther away than from Earth.

The liquid of a liquid mirror telescope is held in a huge dish. The dish slowly spins, creating a surface that is:

flat

curved

pointy

Are you right?

Correct!

In a rotating dish, liquid naturally forms a curved shape. The dish in a liquid mirror telescope spins slowly on electromagnetic bearings. This rotation is steady enough that waves don't form on the liquid surface. Instead, the surface is as smooth as a solid.

Scientists have built liquid mirror telescopes on Earth. What reflective liquid did they use to form the main "mirror"?

water

oil

liquid mercury

Are you right?

Correct!

Yup! But scientists can't use mercury on the Moon. It would freeze! The average temperature on the Moon is about -100°F (-73°C). Scientists are testing certain liquids that won't freeze in very cold temperatures.

A liquid mirror telescope is much heavier than a traditional reflecting telescope of the same size.

Fact
or
Fiction
?

Fiction

In fact, a traditional telescope would probably be too heavy to carry out of Earth's orbit. A liquid mirror telescope would be lighter and easier to transport to the Moon.

A liquid mirror telescope on the Moon could be larger than a football field.

Fact
or
Fiction
?

Fact

On Earth, the largest telescope of this kind is 6 meters (20 feet) across. On the Moon, it could be much larger because there's no wind or weather to disturb the liquid.

Description: a telescope that uses a slowly spinning pool of liquid as the mirror to detect light
Largest on Earth: the Large Zenith Telescope in Canada
Possible Location: the Moon's South Pole
Cool Fact: The light that we see from stars has taken millions or billions of years to reach us. For example, if a star 100 million light years away exploded today, people on Earth wouldn't see the explosion for 100 million years!