If the Sun Is That Hot, Why Is Space So Cold?

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If the Sun Is That Hot, Why Is Space So Cold?

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Published in > Space · 9 January 2022
We live in a universe of extremes. If the Sun is that hot, why is space so cold? Great question…

Unlike our temperate habitat on Earth, the Solar System is full of extreme temperatures. The sun is a ball of gas and flames with a core of about 15 million and a surface reaching 10,000 ° C. However, the cosmic background temperature (the space temperature when you go far enough and escape from the Earth's hot atmosphere) hovers around -270 degrees. So how can this be?

Heat moves in the form of radiation (radiation) in the universe; that is, in the form of an infrared wave that migrates from warmer objects to cooler ones. These radiation waves stimulate the molecules they come into contact with and cause them to heat. This is how heat travels from the Sun to the Earth. But the important point here is that radiation only heats molecules and substances in its path. Everything else remains cold. Take Mercury: According to NASA, the night temperature of the planet may be 540 ° C lower than the part of the day that is exposed to radiation.

Compare this to Earth where the air around you stays warm even in the shade; In some seasons the weather stays warm even in the dark of night. This is because heat travels in three ways rather than one on our beautiful, blue planet. These methods are conduction, convection and radiation. When the sun's radiation hits the molecules in our atmosphere and heats them, they transfer the extra heat to the molecules around them. These molecules then bump into their neighbors and heat them. This heat transfer from molecule to molecule is called heat conduction. This chain reaction warms areas outside the Sun's path.

But space is made up of emptiness. Because the gas molecules in space are so few and far apart, they don't collide all the time. Therefore, even if the Sun heats them with infrared waves, it is not possible to transfer this heat through conduction. Similarly, convection, a form of heat transfer in the presence of gravity, is also important in the spread of heat across the Earth. But this phenomenon doesn't happen without gravity.

Elisabeth Abel, a thermal engineer working on NASA's DART project, thinks of such things when preparing vehicles and devices for long-term journeys in space. This was particularly true when working on Parker Solar Research Tool, he said.

As the name suggests, the Parker Solar Probe is part of NASA's solar research mission. The vehicle quickly passes through the outer layer of the star's atmosphere called corona (crown) and collects data. In April 2019, the device came within 24 million km of this hellish place. A spacecraft has come this close to the Sun for the first time. But this is made possible by the heat layer placed on one side of the vehicle.

"The job of that heat shield," says Abel, "is to make sure that solar radiation doesn't get into the spacecraft." Thus, although the heat shield was subjected to an extraordinary heat from our parent star (about 121 ° C), the spacecraft itself was much cooler (about -150 ° C).

DART's chief thermal engineer, Abel, a tiny spacecraft designed to collide with an asteroid and deflect it from its path, takes practical steps to cope with temperatures in the depths of space. This extraordinary temperature difference between the icy cold space and the scorching heat from the Sun poses unique challenges. Some parts of the spacecraft must remain cool enough to prevent a short circuit; Other parts should be kept warm enough to continue working.

Preparing for hundreds of degrees of temperature changes may sound crazy; but that's exactly how things are in space. What's really strange is Earth: Amidst extreme cold and hot temperatures, our atmosphere is surprisingly mild; at least for now…

Source: Popular Science

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