According to a recent YouGov poll, 35% of Americans think Pluto is not a planet. But they are all wrong—kind of. To get to ...

The number of planets that orbit the sun depends on what you mean by “planet,” and that’s not so easy to define ...

Eight billion miles (14 billion kilometers) from Earth, at the solar system’s ragged edge, lies Eris — a planet-sized ... in December 2004. Sedna’s 11,400-year orbit carries it to an ...

The discovery of the dwarf planet Sedna in late 2003 marked the first identified ETNO. After Sedna’s discovery, astronomers couldn’t help but wonder what was causing its peculiar orbit. Was it a ...

There are eight planets in the solar system, and each travels on its own path around the sun. But of these planets, which is nearest to the sun? Mercury is a strange little world. There are some ...

The building blocks of life could have been delivered to Ceres by one or more space rocks from the outer asteroid belt.

Hot Jupiters are giant planets initially known to orbit alone close to their star ... In addition, a much more massive companion, probably a brown dwarf (a celestial body whose mass is between ...

For Neptune, in its wide and distant orbit at about 30 AU, the difference between the perihelion and aphelion is 0.5 AU, according to the Royal Greenwich Observatory. Dwarf planet Pluto ...

After 11 years in solar orbit, the European Space Agency’s Gaia ... Gaia has also strengthened the hypothesis that our own yellow dwarf star formed much further in towards the center of our ...