Cynthia Checketts with Clark Planetarium says liquid nitrogen is almost as cold as the planet Pluto!
She explains that nitrogen is usually a gas at room temperature.
But, she can make it liquid by decreasing the temperature to almost -320 degrees Fahrenheit!
With someone so cold, she showed us how things like fresh flowers can instantly freeze. Even puffy marshmallows are hard enough to break with a hammer after a few seconds.
Cynthia says, because it's so cold... it only takes a little bit to heat it up to the boiling point, as she proved when she put the liquid nitrogen into a tea kettle. It started to whistle right away!
You can see more fun science experiments like this in person at Clark Planetarium, or by visiting their website, clarkplanetarium.org.