Decades ago, the Morning Glory pool at Yellowstone National Park was a gorgeous deep blue. But because tourists have thrown coins, rocks, and trash into it for years, the spring has now turned into a sickly yellowish green. Now, a new optics study is shedding light on the pool's unfortunate change of color.
The fossil record reveals the last 3.4 billion years of life on Earth. But before then, when life first emerged, we have next to nothing. The consensus view is that life began in the oceans... but there might be another, weirder, possibility.