How big can a planet be? With very large gas giants, it can be hard to tell
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How big can a planet be? With very large gas giants, it can be hard to tell

Gas giants are large planets mostly composed of helium and/or hydrogen. Although these planets have dense cores, they don't have hard surfaces. Jupiter and Saturn are the gas giants in our solar system, but there are many other gas giant exoplanets in our galaxy and some are many times larger than Jupiter.