Why is outer space so cold

But why is the vacuum of space this cold? Well, it's complicated. Another Burning Question. Event Horizon Telescope collaboration et al. You may be able to find the same content in another format, or you may be able to find more information, at their web site. Related Stories. Xuanyu Han Getty Images. Related Story. A barebones telescope with a 76mm that's great at getting anyone started with astronomy.

AWB OneSky. Levenhuk Skyline. Celestron bhphotovideo. Orion SkyQuest XT8. Celestron NexStar 6 SE. Orion SkyQuest XT10i. Celestron NexStar 8 SE.

Why is space so cold if the sun is so hot? Excellent question. Unlike our mild habitat here on Earth, our solar system is full of temperature extremes. The sun is a bolus of gas and fire measuring around 27 million degrees Fahrenheit at its core and 10, degrees at its surface. How can this be? Heat travels through the cosmos as radiation, an infrared wave of energy that migrates from hotter objects to cooler ones.

The radiation waves excite molecules they come in contact with, causing them to heat up. Meanwhile, the shaded side of our truck is emitting infrared light too—just at a slower rate. Insulated by vacuum, it will cool down much more slowly than the sunlit side heats up, but since there is no energy coming in, it will keep on cooling down until it gets very cold indeed. Of course, in the real world, nothing is quite so tidy.

Our Mac Truck will probably be tumbling so neither side will have enough time to fully heat up or cool down. This idea was used during the Apollo program, where the large, cylindrical Service Module was frequently set into a gentle rotation to keep the temperatures even. Objects also conduct heat internally so the shadowed side of an object sitting in the sunlight near Earth might cool down to only degrees Fahrenheit , where at the orbit of Pluto, it might be more like degrees.

All this is very important to spacecraft designers. From the sun out to about the orbit of Mars, spacecraft have little trouble staying warm. They mostly are wrapped in reflective materials for protection from the sun, and given radiators or other systems to help get rid of the heat generated by their systems.

Quick heat transfer requires contact or air, both lacking in space. As a result objects cool very slowly through the much slower mechanism of thermal radiation. A human exposed to outer space in shadow without a space suit does not instantly freeze to a block of ice. Topics: cold , cold space , temperature , thermal radiation , vacuum.