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Does it rain in space?

Asked By

Abby Lewis

School: Tioughnioga Riverside Academy, Whitney Point CSD
Grade: 5
Teacher: Miss Babcock
Hobbies/Interests: Soccer, art, hiking
Career Interest: Doctor

Answered By

Stuart Shepard

PhD Candidate
Research area: Computational physics. His current research involves simulating the transfer of electricity through single molecules to see if they could be used as building blocks in nanoscale electronic devices. Interests/hobbies: Playing and listening to music, playing soccer at Binghamton’s Recreation Park, traveling, and learning more and more about physi

Sadly, when it comes to space weather, there is 0% chance of rain. To understand why we don’t get rain in space, we need to understand how rain happens on Earth. 

It all starts with energy from the Sun, which warms the Earth’s surface. Warm temperatures cause water from the oceans and lakes to evaporate (change from a liquid to a gas) and rise up into the atmosphere. As the gaseous water, or water vapor, rises, it cools and condenses (changes from a gas back to a liquid) to form tiny water droplets, which we see as clouds. Finally, when the water droplets get large and heavy enough, they fall back to the ground under Earth’s gravity as rain. 

This process, called the water cycle, all occurs within the lowest part of the atmosphere, the part we live and breathe in, called the troposphere. In fact, all the familiar weather events like wind, clouds, rain and snow happen in the troposphere, which extends about 10 miles above the ground we walk on. That means, if there was a road going straight up in the sky, it would only take about 15 minutes to drive, depending on traffic, through the troposphere, and you would be able to look back down on all the rainy weather. Larger airplanes going long distances will travel in the upper part of the troposphere to reduce turbulence and avoid bad weather. The rest of Earth’s atmosphere extends way higher than the troposphere, to about 300 miles above the ground, where we find the outermost layer of the atmosphere, called the exosphere. Although still part of the Earth’s atmosphere, this is the layer where the International Space Station orbits the Earth, so the line where the atmosphere ends and where space begins is not really all that clear. 

So, just above the troposphere (looking down on all the clouds), we haven’t even come close to reaching "space," and already the chance of rain is very low. As we leave Earth’s atmosphere and enter space, well, it’s pretty empty, with no air or atmosphere for clouds to form in and no water to form the clouds, and so, no rain.

While it does not rain in space, we can find interesting weather on other planets. Under the right conditions, a planet will form an atmosphere which is held in place around the planet by its own gravity, the same way Earth’s gravity holds you on the ground. You can think of an atmosphere as a bunch of different gases (such as water vapor) surrounding the planet, just like how an orange’s skin surrounds an orange. Different planets have different atmospheres, which can lead to weather very different than what we see on Earth. For example, on Uranus and Neptune, it is expected that instead of water falling from the sky, carbon, in the form of diamonds, falls like rain. While this would definitely be "enriching" to see, those atmospheric conditions would also make it unsuitable for humans to survive.

There is currently an ongoing effort to find planets with atmospheres where rain would fall like it does on Earth, since this would be a sign that life as we know it could thrive and could even serve as a new home in the far future. Hopefully it does rain in space, in the atmospheres of possibly life-harboring planets other than Earth.

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