A comical planetary beauty contest is described, highlighting the unique traits of each planet: Mercury’s fiery nature, Venus ...

Trans-Neptunian objects (TNOs) are icy bodies that vary widely in size, from large dwarf planets like Pluto and Eris—each ...

Mars, Venus, Jupiter and Saturn should be visible to the naked eye, but with a telescope you can spot Neptune and Uranus.

For decades, we believed there were nine planets in our solar system—until Pluto was reclassified in 2006. But what if ...

These popular astronomy questions, answered by Astronomy magazine, will help you better understand our universe - and share ...

Take advantage of a special 6-7 planet alignment from Earth's perspective. Planets 'line up' in the skies over California in ...

For the first time, astronomers have imaged dozens of belts around nearby stars where comets and tiny pebbles within them are ...

Does our Solar System have 9 planets or only 8? Astronomers have gone back and forth on that a lot, with Pluto now being classified as a dwarf planet. However, out beyond Neptune there could be ...

In August 2006, the International Astronomical Union made the controversial, but correct, decision to demote Pluto from its ...

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 bottom of whether Pluto is a planet, I tracked down planetary scientist ...

Welcome to this month’s edition of “What’s up in the sky?” February has a nice lineup of planets and some eye-catching ...

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