Elon Musk: @waitbutwhy 按质量计算，地球由约 32% 的铁组成。按质量计算，其次最常见的元素是约 30% 的氧气，但其中只有一小部分存在于大气中。

原推：@waitbutwhy By mass, Earth is composed of ~32% Iron. Next most common element by mass is oxygen at ~30%, but only a small portion of that is in the atmosphere.
https://twitter.com/elonmusk/status/1520934305274421250