Indeed, as we search for life on other planets, we've used the Earth as our standard reference. Practically speaking, it's the only model we've got — and it appears to be a pretty damned good one; Earth has been teeming with life for billions of years and, quite importantly, it's even spawned a radio-capable, space-faring civilization.
That being said, what makes us so sure it's the best model for habitability? Could other planets or moons be even more suitable for life? A pair of astrobiologists say yes. To find a habitable and ultimately an inhabited world, they argue we should adopt a biocentric approach rather than a geo- or anthropocentric one.
"Planet X" might actually exist — and so might "Planet Y."
At least two planets larger than Earth likely lurk in the dark depths of space far beyond Pluto, just waiting to be discovered, a new analysis of the orbits of "extreme trans-Neptunian objects" (ETNOs) suggests.
Researchers studied 13 ETNOs — frigid bodies such as the dwarf planet Sedna that cruise around the sun at great distances in elliptical paths.