Researchers say that our own planet could paradoxically offer ... and space-based telescopes could detect. "If purple bacteria are thriving on the surface of a frozen Earth, an ocean world ...

The first life forms used retinal instead of chlorophyll, absorbing green light and reflecting red and blue—turning the planet an eerie purple. Chlorophyll wasn’t always king. Retinal ...

And in its own way, the planet’s rusty red surface tells a story of destruction. Billions of years ago, the fourth planet from the sun could have been mistaken for Earth’s smaller twin ...