There may be a warp in the Kuiper Belt, possibly caused by “Planet Y” — a Mercury-to-Earth-sized world that orbits the sun way beyond the orbit of Neptune. Is there a mysterious “Planet Y” orbiting ...

Mercury currently appears as a bright "evening star" in the southwestern sky at sunset. Mercury will reach its greatest eastern elongation on Oct. 29, marking one of the best evenings to see the ...

An "extra exceptional" Tatooine-like exoplanet, orbiting two suns, has been discovered. Astronomers say the "huge" new world ...

Mars and Mercury will appear close to one another in the southwestern sky on Nov. 12. Look low on the southwestern horizon at sunset on Nov. 12 for a chance to see swift Mercury close to the red light ...

WASHINGTON, March 13 (Reuters) - Astronomers have identified a quartet of small rocky planets orbiting Barnard's star - one of our closest stellar neighbors - though they concluded that all of them ...