NEW YORK (AP) — A new Tatooine-like planet outside the solar system may orbit two failed stars, scientists reported Wednesday. Located about 120 light years away, the exoplanet appears to take an ...

Is there a massive undiscovered planet on the outer reaches of the Solar System? The idea has been around since before the discovery of Pluto in the 1930s. Labelled as planet X, prominent astronomers ...

Pluto's unusual eccentricity and tilt is likely due to its interactions with neighboring Neptune and other giant planets, ...

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Astronomers have identified a strikingly large gas giant orbiting a remarkably small red dwarf star — a finding that challenges long-standing assumptions about how planetary systems form. The ...

(Correction: An earlier version of this story misstated how far Pluto is from the sun. The correct number is 3.7 billion miles.) What was discovered in Flagstaff, Arizona, and killed off in Prague? If ...

Astronomers have identified an enormous "growth spurt" in a so-called rogue planet. Unlike the planets in our solar system, ...