It depends on which part of space we are talking about. In general, it works like this: the closer to the stars, the higher the temperature. Another factor that weighs is the presence of matter: heat can be retained by it. As space becomes empty, the temperature drops. In total vacuum (absence of matter), the temperature plummets to minus 272°C, 1 degree above absolute zero. “It’s like measuring the minimum temperature of space. There is no place cooler than this. They are empty regions far from heated bodies”, says astronomer Enos Picazzio, from USP’s Institute of Astronomy, Geophysics and Atmospheric Sciences. To get an idea of the cold weather, the lowest temperature ever recorded on Earth was minus 89.2 ºC, in Antarctica. In interstellar space, where absolute emptiness does not reign (there are gases, grains and dust), the temperature varies. At the top of the Earth’s atmosphere, for example, the temperature is somewhere around 27°C. “But that doesn’t mean that the space above the atmosphere is at that temperature. In fact, it is cold, but a body in this region that is illuminated by the Sun can reach this temperature. In the dark, the temperature would drop a lot”, says Picazzio. On the Moon, which has no atmosphere, temperatures vary greatly: with the Sun overhead, the satellite’s surface exceeds 100°C and drops to -150°C during the night.
SUN
The temperature of the part of the Sun that is visible from Earth, the photosphere (a thin, bright and well-defined layer, considered its surface), is 5,500 ºC, but some stars can exceed 50,000 ºC. Inside the Sun, however, things heat up: the heat reaches 15 million degrees!
SOLID PLANETS
Our dear Earth is kept warm thanks to the atmosphere and its five layers. Solar radiation and its interaction with the Earth’s soil define how hot it is here. About 47% of the heat emitted by the Sun is absorbed by the Earth. The other solid planets in the solar system are Mercury, Venus and Mars
INTERPLANETARY SPACE
In the space between the planets or between the stars, there is little matter, composed mainly of gases and space dust. The air is rarefied and, although the temperature can reach around 27ºC in the space between the Earth and the Moon, for example, the sensation we would have there (without special clothing) would be cold, because the few molecules existing there do not are sufficient to transfer a significant amount of heat to our skin or to spacecraft.
GAS PLANETS
Without a solid surface, the gaseous material simply gets denser with depth, eventually reaching a liquid state. Composed mainly of hydrogen and helium, Jupiter, Saturn, Uranus and Neptune, in addition to not having solid matter, are further away from the Sun, which makes heat rare there. Only in the deepest layers are they hot
ABSOLUTE COLD
Formed by a cloud of gas and dust, the Boomerang nebula registers a temperature of minus 272 °C (1 kelvin), just 1 degree above absolute zero. Apparently, it is the coldest place in the Universe, but the mystery has not yet been fully unraveled. The nebula is located in Centaurus, one of the constellations of the Milky Way, in the southeastern celestial hemisphere, 5,000 light years from Earth.
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