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The Coolest Gas in the Universe
Do you live north of the equator? If you do, it is now autumn where you live. Winter will be coming soon. The air will be colder outside. There are places on Earth that can get colder than 0 degrees Fahrenheit. That's colder than freezing! If it is colder than 0 F, you put a minus (-) in front of the number. So, if the air is 10 degrees below zero, it looks like this: -10 F.

Top half of a world map
Image above: These areas are all north of the equator. This is called the Northern Hemisphere. Credit: NASA
Where do you think it gets the coldest on Earth? And how cold can it get? Antarctica was the coldest that we know of. This is where we find the South Pole. One day, the temperature was -132 F.

Hot Space, Cold Space
What is the temperature in space? Objects in space around Earth can be very hot or very cold. They can reach 250 F. Or they can drop to -185 F. It is hot in the sunlight and cold in the shade. It can get very cold, but that's not the coldest place. The planet Pluto may be -350 F. And that's not the coldest!

Drawing of a thermometer acting cold
Image above: This thermometer shows it's very cold outside! Credit: NASA

How Low Can You Go?
Absolute zero is the coldest. It is -459 F. Now that is cold!

Everything is made of atoms. We cannot see them. All of the atoms are moving. Moving atoms make the states of matter. Do you know about three states of matter? There are gases, liquids and solids. The atoms in a gas move very fast. The atoms in a liquid move a little slower. The atoms in a solid move so slowly that you cannot see movement. Absolute zero is so cold that the atoms do not move at all.

More Than Three
Scientists can get a gas very cool. They can make it so cold that it is a different state of matter. But how do you catch a gas to make it cold? Scientists use a laser beam to hold the atoms together. It is not a gas anymore. It is not a liquid. It is not a solid. It is a new state of matter. Scientists think that there may be more than three states of matter. They think that there may be around 100 states of matter.

Scientists can make a gas so cold, that it is the coolest gas in the Universe.

Adapted from What is the Coolest Gas in the Universe?
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