Everyone's favorite dwarf planet, Pluto, was discovered just 95 years ago. Here's the story of how the once-ninth planet was ...

Once, a gassy envelope of hydrogen and helium surrounded our infant world. Over millions of years, that atmosphere escaped into space. Pluto is the only place in the solar system where we can ...

Our solar system has eight planets but in recent years, astronomers have theorised there could well be a ninth planet that's hiding in our solar system we've not been able to see yet.

and Vesta as full-fledged members of our planetary system. Today, when tens of thousands of minor planets have been discovered (most residing in an "asteroid belt" between Mars and Pluto), not ...

Pluto was once called the ninth planet, but in 2006, scientists changed its status to a dwarf planet. A planet must clear its orbit of other objects, but Pluto shares its space with many small icy ...

Our solar system is probably on the mild side compared ... mission called New Horizons that will send an unmanned probe past Pluto and its five known moons in July 2015. From there Stern hopes ...

Planets' temperatures are largely influenced by their structural characteristics and proximity to the Sun, however, Venus ...

With the exception of Pluto, planets in our solar system are classified as either terrestrial (Earth-like) or Jovian (Jupiter-like) planets. Terrestrial planets include Mercury, Venus, Earth ...

Pluto is just 1,400 miles wide, about half the width of the U.S. "It definitely kind of broke the mold," van Belle said. "In our inner solar system, we have the four terrestrial rocky planets ...

The relative quantities of volatile gases like methane and ethane can reveal key details about distant Kuiper Belt objects.

The first time you may have heard the term ‘dwarf planet’ was when Pluto got demoted to one in 2006 (RIP). However, we actually have six in our Solar System. Pluto, Ceres, Makemake ...