* The most abundant elements in the universe are hydrogen and helium. This is because they were the first elements formed after the Big Bang.
* Gas giants are mostly hydrogen and helium. Planets like Jupiter, Saturn, Uranus, and Neptune are large and gaseous, containing mostly hydrogen and helium with smaller amounts of other elements like methane, ammonia, and water.
* Rocky planets are mostly different elements. Planets like Earth, Mars, Venus, and Mercury are primarily made up of heavier elements like iron, silicon, oxygen, and magnesium.
So, why is it misleading to say planets are mostly helium?
* It's inaccurate. Most planets aren't primarily composed of helium.
* It ignores the vast differences in planet types. Gas giants are vastly different from rocky planets in their composition.
* It oversimplifies the complexity of planetary formation. The specific elements found in a planet depend on the specific conditions in the solar nebula where it formed.
In summary: While helium is a common element in the universe, it's not the dominant element in most planets. Gas giants have a high abundance of hydrogen and helium, while rocky planets have a much greater proportion of heavier elements.
