Imagine a world where the Sun never rises — or never sets. That’s the reality on many exoplanets that are tidally locked to their stars. On these planets, one side always faces the star in scorching daylight, while the other remains frozen in eternal night. But in between lies something ...

"Was There Ever a Time When Earth Was Purple?" What if Earth wasn’t always blue and green… but purple? According to the Purple Earth Hypothesis, the earliest life forms may have used a different light-absorbing pigment — retinal — giving Earth a deep violet glow billions of years ago! In ...