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You are watching: Which type of heat transfer can happen through empty space?




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How does warmth travel through an are if room is a vacuum? – Katerina, period ten, Norwich, UK.

What a great question!

First off, to understand what warm is, you need to know that whatever you deserve to touch or check out is consisted of of tiny building blocks called atoms. Atoms are so small that you can’t even see them (except with some very special equipment) – however they consist of all the issue in the universe.

If miscellaneous is hot, it means that that is atoms have actually lots the energy and are bouncing around. If miscellaneous is cold, the atoms have much much less energy and they stay quite still.

It’s true that space is a vacuum, which way that over there isn’t much issue floating roughly out there. An are isn’t a perfect vacuum though. Even if we disregard the large stuff favor stars, planets and also comets, space is not totally empty.

In fact, the sun is constantly blow matter, recognized as the solar wind, out right into our solar system. This is part of what reasons the beautiful light screen we call the aurora.

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But the solar wind isn’t very dense - it has actually much, lot fewer atom in it than air, for example. This means it can’t lug much warmth in it and so the can’t describe how the warmth from the sunlight reaches Earth.

There space three ways heat can be shared: conduction, convection and also radiation. Let’s think about each of these in turn, to uncover which one permits heat come travel with space.


Conduction is what scientists speak to the deliver of warm through touching. If girlfriend touch miscellaneous warm, heat goes native it come you. If friend touch other cold, warmth goes indigenous you come it.

Some materials, such together metals, are an excellent conductors. Other materials, such as glass, are poor conductors, and also are called insulators.

Heat can also be conducted in much more than one step. Because that example, if you hold a steel spoon in a mug of hot tea, warm will be transferred from the tea to the spoon, and then indigenous the spoon to your hand.


from tea come you. Rawpixel/Unsplash., FAL

But we’re not emotional the sun (and it is a great thing too - its surface temperature is over 5,000°C!) and room is a vacuum so over there isn’t anything to act together a spoon and conduct the heat. So we can dominion out conduction.


Convection is the transfer of heat through the circulation of fluids. Both liquids and gases deserve to convect heat. Atoms will circulation away from hot regions towards cooler regions, transporting their heat and also energy through them.

If did you do it ever remained in a bathtub that has started to walk cold, and also then revolve the warm tap on, you’ll feel the warm water convect native the tap more into the bath.

The hot atoms will then bump into cooler atoms, share their heat through conduction, till the bath becomes an even temperature.

But because an are is a vacuum, there room no liquids or gases come convect warmth away from the sun, all the method to Earth. So us can preeminence out convection.


Hot body of issue such as the sunlight – and also even our own human being bodies – offer off heat. Together the matter’s atom move and also vibrate they give off, or “radiate”, electromagnetic power – this is dubbed “thermal radiation”.

Electromagnetic power comes in a range, or spectrum, of varieties - few of these we have the right to see: they consist of the rainbow the “visible light”. Other varieties that we cannot see exist too, such together the infrared power our hot bodies radiate and also microwave energy we usage to cook food.


A heat camera allows you ‘see’ heat, by choose up thermal radiation. Shutterstock.

Unlike conduction and convection, radiation does no need issue to move heat. Energy is radiated native the sun, v the vacuum of space at the rate of light. Once this energy arrives in ~ Earth, some of it is moved to the gases in ours atmosphere.

Some of it passes through and heats increase the atom on the earth surface. Part will even be soaked up by your skin.

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The floor soaks up the power from the sun’s radiation, and also this causes it to give off heat, too. Several of this warm is conducted – like when the warm sand top top the beach burns her feet in the summer. Part is convected with wind and ocean currents, and some of that is radiated earlier into the atmosphere, or also outer space.