There could be "dark main sequence" stars at the galactic center
The initial mass of a star determines its rate of hydrogen burning and subsequent evolution into heavier element fusion. This is integrated into the main sequence, a systematic classification for stars.
A Planet Money guide to 5 fascinating new econ papers
Firewood was humanity's main energy source for centuries, but solid statistics about prices have been difficult to find due to many Americans chopping down wood themselves.
China Burns 10x More Coal Than the US -- Way More Than Any Other Nation on Earth
Coal remains one of the most heavily used energy sources globally, fueling economies from China to the US and practically every country in between. Despite the rise of green energy, coal consumption is integral for these economies.