For the first time, NASA’s Hubble Space Telescope has seen distinctly the “tenth planet,” currently nicknamed “Xena,” and found that it’s only slightly larger than Pluto.
Though previous ground-based observations suggested that Xena’s diameter was about 30 percent greater than Pluto, Hubble observations taken Dec. 9 and 10, 2005, showed Xena’s diameter as 1,490 miles (with [...]