There is an assumption that space is extremely cold. In fact, it largely depends on where you are in space; so you don’t always freeze when you are unprotected. There are situations where you can burn, and there are situations where even a spacecraft can melt down.
Starting very close, the International Space Station (ISS) orbits only 400 kilometers above the ground, but without the protection of the atmosphere, it is exposed to extreme temperatures not seen on Earth.
At its coldest, thermometers show a temperature of around -157°C, a temperature at which even pure propyl alcohol freezes. This happens when the ISS passes behind Earth. When the station returns to sunlight, the temperature rises to 121 °C. Similar extremes are seen between day and night on the Moon. In other words, not every place or every time zone is at the same temperature. It can be very cold, or it can be very hot.
The temperature in interplanetary space depends on how close you are to the Sun, and you don’t have to get very close to it to reach an incredibly high temperature. Corona, which can be defined as the atmosphere of the sun, stretches for millions of kilometers and has a temperature of millions of degrees at its hottest moment. NASA’s Parker Solar Probe passes through the outer layers of the corona. But it doesn’t have a camera aimed at the Sun because at this close range, the sunlight gets hot enough to melt the inside of the spacecraft.
Large cosmic objects also affect temperature
Temperature changes are also seen near any large cosmic object. Stars, black holes, planets and more affect the surrounding temperature. But we can actually say that it is possible to measure the temperature of the cosmos in general. This measurement comes from the Cosmic Microwave Background (CMB), the first light to move unhindered in the universe.
In the early universe, everything was so hot that this light was constantly removing electrons from atoms, being absorbed and re-emitted in the process. The universe began to cool until this light was released due to the expansion of the universe.
The universe has been expanding and cooling ever since. It currently has a temperature of 2.73 Kelvin (-270.4°C). So it’s just a few degrees above absolute zero, the lowest temperature.
How hot a substance is basically defines how energetic its particles are. More energy means more heat. At absolute zero, particles have zero energy and are at rest.
There are certainly warmer places in the universe, even in intergalactic space, where tremendous temperatures can be seen thanks to the jets of matter accelerated by supermassive black holes and gas pulled by gravity.
Surprisingly, there are also colder places than CMB. The Boomerang Nebula is one of them, and researchers have recently discovered how it can get a little cooler than the rest of the Universe.
Spacesuits don’t just protect from the cold
Space suits are not designed to keep the wearer warm. It is designed to keep astronauts at a comfortable temperature regardless of the outside temperature. As we can see, the outdoor temperature can fluctuate a lot around the Earth.
The development of lightweight insulation was instrumental in ensuring astronaut safety. NASA refers to it as a “luminescent barrier.” This material is used in buildings, emergency blankets, lighting fixtures and even cell phone cases.
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