Hello there, I'm an expert in the field of planetary science with a keen interest in the composition of planetary atmospheres. It's fascinating to delve into the various gases that make up the atmospheres of our neighboring planets and beyond.

The presence of carbon dioxide (CO2) in a planet's atmosphere can tell us a lot about the planet's geological activity, climate, and even its potential to support life. It's a greenhouse gas that can trap heat and create a warming effect on a planet's surface, much like what we see on Earth.

Jupiter and Saturn, the gas giants, are indeed dominated by hydrogen and helium, which are the most abundant elements in the universe. However, these planets also contain trace amounts of other gases, including carbon dioxide. The atmospheres of these planets are complex and dynamic, with layers of clouds and storms that can trap and transport gases like CO2.

Venus stands out with its thick atmosphere that is remarkably rich in carbon dioxide. Approximately 96% of Venus's atmosphere is CO2, which contributes to the planet's extreme greenhouse effect and makes it the hottest planet in our solar system, even hotter than Mercury which is closer to the Sun. The high concentration of CO2 on Venus also plays a role in the planet's sulfuric acid clouds and its unique weather patterns.

Mars, on the other hand, has a much thinner atmosphere, with carbon dioxide making up the majority of it, around 95%. This is similar to the ratio found in Venus's atmosphere, but the overall pressure and temperature on Mars are much lower. The Martian atmosphere also contains nitrogen, argon, and trace amounts of oxygen and water vapor. The presence of CO2 on Mars is significant for future missions and potential colonization, as it could be a resource for producing oxygen and fuel.

Earth, of course, has a different balance. While carbon dioxide is present, it makes up a much smaller percentage of our atmosphere, around 0.04%. Earth's atmosphere is primarily composed of nitrogen (78%) and oxygen (21%), with argon and other gases making up the remainder. The relatively low concentration of CO2 on Earth is crucial for maintaining a climate suitable for life as we know it.

In the search for exoplanets, astronomers are also looking for signs of carbon dioxide in the atmospheres of distant worlds. The detection of CO2 can indicate the presence of a greenhouse effect and provide clues about a planet's temperature and potential habitability.

Studying the composition of planetary atmospheres is crucial for understanding the formation and evolution of planets, as well as their potential to host life. It's a field that continues to grow with new discoveries and advancements in technology, offering exciting opportunities for further exploration and learning.

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It's an odd mix compared to the atmospheres of other planets. Jupiter and Saturn are dominated by hydrogen and helium, The thick atmosphere of Venus is about 96% carbon dioxide, and only 3% nitrogen, which is about the same ratio as the thin atmosphere of Mars.Aug 15, 2016read more >>