It is so bitterly cold in space

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Space: The temperature there is close to absolute zero. (Source: IMAGO / Addictive Stock / Shotshop)

Space is an uncomfortable place. Hot regions alternate with bitterly cold areas. Why is that?

In science fiction films, space is a cold and inhospitable place. Explosions tear holes in spaceships and throw their occupants outside. There they float through space, frozen forever.

What’s wrong with the assumption that space is so bitterly cold? The answer is complicated.

First: From a purely physical point of view, space has no temperature. Even if there is a vacuum there, elementary particles, gases, cosmic dust and other particles still move through the vacuum.

These particles are what create a temperature in the vacuum of space. The faster the particles move through space, the higher the energy and temperature generated.

2,700 degrees after the Big Bang

Since the universe has been expanding rapidly since the Big Bang, it was incredibly hot shortly after its creation. Scientists estimate that 380,000 years after the Big Bang the temperature was around 2,700 degrees.

According to the Max Planck Institute, after the Big Bang, a hot and cloudy soup “of radiation and elementary particles swirled in space.” As the universe expanded rapidly, density and temperature continued to decrease.

But as the universe continued to expand and particle movement slowed down, space became increasingly cooler. Today the temperature is minus 270.42 degrees Celsius.

Absolute zero is the lowest temperature limit

That’s only about three degrees away from physical absolute zero. Particles come to a standstill at minus 273.15 degrees Celsius. This temperature is also called the “lowest possible temperature”. Nothing can be colder than absolute zero.

But temperatures are not so low everywhere in space. Near stars, for example, it is scorching hot. According to a study by the University of Heidelberg , measurements by astronomers show that the surface temperatures of the stars are between around 1,700 degrees for so-called red stars and 30,000 degrees for blue stars.

Close-up of the sun: Inside the star it is unimaginably hot at 15 million degrees Celsius.
Close-up of the sun: Inside the star it is unimaginably hot at 15 million degrees Celsius. (Source: NASA / SDO)

The surface of stars like our sun is said to be around 5,80So space is a place of extremes. Hot and cold areas alternate. For us humans, this is not a place where we could live without equipment such as protective suits or spacecraft.0 degrees hot. Inside these stars there are temperatures of 15 million degrees Celsius. Inconceivably.


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