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Fact check: Soda experiment does not disprove existence of gas planets

Kate S. Petersen, USA TODAY
·5 min read

The claim: Gas planets can't exist because space is a vacuum

NASA reports more than 400 gas giants – large gas planets like Jupiter or Saturn – have been discovered outside of Earth's solar system.

However, the possibility that a gas planet could exist in the vacuum of space has been challenged by some social media users.

For instance, a meme posted on Facebook Jan. 6 features a progression of photos showing the rupture of a can of soda exposed to a vacuum.

"This simple experiment, in which a soda can exposed to a vacuum environment explodes, demonstrates the impossibility of the existence of a pressurized environment within a vacuum without the presence of a suitable container," reads the meme, which garnered more than 600 interactions in a week.

The meme also includes images of Jupiter, Saturn, Uranus and Neptune.

"'Gaseous planets' as NASA tells us cannot exist," is written under the planets.

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The meme was posted on Facebook throughout 2021, before surfacing again this month.

However, the meme's comparison and conclusion are wrong. Self-gravity – the gravitational force that holds sufficiently massive objects together – allows gas planets to maintain their form in the vacuum of space. Multiple lines of evidence show gas planets exist, according to researchers.

USA TODAY reached out to social media users who shared the meme for comment.

Gas planets maintain form due to self-gravity

The meme is correct that soda remains inside a can given the external pressures at sea level, because the can prevents it from escaping. The can is strong enough to do this even though there is a mild pressure difference – or gradient – between the outside and inside of the can.

"Aluminum cans are pressurized to hold in the fizz from the carbon dioxide," according to Elise Knittle, an Earth and planetary sciences professor at University of California, Santa Cruz.

The strength of the can itself and the opposing force from atmospheric pressure are enough to keep the soda inside the can.

However, when the pressure outside the can drops in a vacuum chamber, the difference in pressure may become too great.

This may cause the can to rupture, followed by the rapid release of the soda, because regions of higher pressure will move – or diffuse – across the gradient into regions of lower pressure, Knittle told USA TODAY in an email.

“The gradient ... drives the diffusion process,” she said.

The meme is wrong to compare a soda can in a vacuum chamber to a gas planet in space.

“For the soda, the explosion is due to the increase in the pressure gradient between the can and atmosphere,” said Knittle. But for gas planets “the gravity is so great from the planet that it counteracts the pressure gradient between outer space and the planet."

Gravitational force scales with mass. An object has to be a certain mass for its own self-gravity to hold it together even when acted on by diffusion or other forces.

A can of soda does not have enough mass to maintain its form through self-gravity.

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Gas planets are not the only example of celestial bodies that resist diffusion due to gravity.

Like gas planets, “stars are just giant balls of gas,” said Knittle. “And they hold together.”

Earth's gas atmosphere is also stable due to gravity, Rebekah Dawson, a professor of astronomy and astrophysics at Pennsylvania State University, told USA TODAY.

Multiple lines of evidence show gas planets exist

In addition to the concept of gas planets being generally compatible with the laws of physics, researchers have established their existence through multiple lines of evidence.

These include spectroscopy – the analysis of the different wavelengths of light moving through a planet's atmosphere or reflected off of it. This technique can help determine the chemical and physical composition of a planet's atmosphere.

"We can detect spectroscopic transitions of molecules – and some atoms – that only exist in a gaseous form,” said Glenn Orton, a research scientist at NASA, told USA TODAY in an email.

Researchers can also deduce the overall density of a planet after determining its mass through gravitational analysis and size through geometric calculations. While gas planets may have some solid elements, their overall density is much less than rocky planets like Earth due to the preponderance of gas in their make-up, said Dawson.

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USA TODAY has debunked other claims that NASA misled the public about space science and exploration.

In one instance, social media users falsely claimed NASA tried to pass off an altered image of a Bulgarian rock formation as the surface of Mars. However, there was no evidence the image was connected to NASA.

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Social media users also falsely claimed the NASA Mars Perserverence rover landing and the flight of the NASA Mars Ingenuity helicopter were impossible due to atmospheric conditions on the planet. In this case, both technologies were constructed to function in Martian conditions.

Our rating: False

Based on our research, we rate FALSE the claim that gas planets can't exist because space is a vacuum. Gas planets maintain their form due to self-gravity. The existence of gas planets has been verified by multiple lines of evidence.

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This article originally appeared on USA TODAY: Fact check: Gas planets persist in vacuum due to gravity