Eight years outbound from Earth, NASA's New Horizons probe passed the orbit of Neptune ... Pluto's enormous distance from Earth -- so far that it will take radio signals some 4.5 hours to cross ...

A new dwarf planet, discovered beyond Neptune and described as Pluto's 'cousin,' could void the hypothesis of a Planet X in our solar system.

Neptune’s orbit is essentially circular and in the same plane as most planets (the ecliptic plane), while Pluto’s orbit is elliptical and tilts 17º to the ecliptic. So, if Pluto and Neptune ...

NASA calls it a cosmic coincidence. On Monday, NASA's New Horizons spacecraft crossed the orbit of Neptune on its way to Pluto. The celestial milestone occurred on the 25th anniversary of Voyager ...

With Pluto spending 20 years of its 248-year orbit within the orbit of Neptune, you might expect that at some point, the two worlds could catastrophically collide. However, Pluto and Neptune never ...

it will cross the orbit of Neptune, and be the closest to the sun of the two bodies. This happened most recently on Feb. 7, 1979-the first time since Pluto was discovered on Feb. 18, 1930.

Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune and Pluto. Many Americans grew up ... It has cleared the neighborhood around its orbit IAU members also concurred that dwarf planets ...