Here’s something to think about as you kick off 2025: We are all stardust. Every atom of oxygen in our lungs, of carbon in our muscles, of calcium in our bones, of iron in our blood—was created inside a star before Earth was born. Hydrogen and helium, the lightest elements, were produced in the Big Bang. Almost all of the other, heavier, elements were produced inside stars. Stars forge heavy elements by fusion in their cores. In a star of intermediate mass, these elements can mix into the star’s atmosphere and be spread into space through stellar winds.
Image: NASA Hubble Space Telescope, CC BY 2.0, flickr