“New Horizons shattered a major paradigm of planetary science,” says Alan Stern, the mission’s principal investigator. “Pluto ...

Saturn, Venus, Neptune, Uranus, Jupiter, Mars and Mercury will be visible in an uncommon planetary alignment this month.

Brown’s team discovered a dwarf planet, Eris, in January 2005. At the time, it appeared to be larger than Pluto. If Pluto hadn’t been demoted, Brown says, hundreds of celestial objects would ...

Clyde Tombaugh didn't set out to discover Pluto when he sent his sketches of the night sky to Lowell Observatory in Flagstaff ...

Pluto may not be a planet any more, but you still have a chance to see the distant dwarf planet at one of Michigan's ...

In August 2006 the International Astronomical Union General Assembly adopted a resolution to reclassify Pluto as a dwarf planet. The reasoning was that it didn't satisfy one of three newly defined ...

Because of this, Pluto no longer fit the definition of a full-fledged planet and was reclassified as a dwarf planet on August 24, 2006. In 2005, astronomers discovered Eris, a celestial body in ...

Arizona in 1930 and was considered our ninth planet until 2006. The International Astronomical Union reclassified Pluto as a dwarf planet because it does not clear its orbit of other debris.

An amateur astronomer discovered Pluto 95 years ago today. The former planet will complete an orbit in another 153 years.

Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute With Pluto's "demotion" to dwarf planet status ... along with bodies like Eris, Ceres and Pallas.