Add Yahoo as a preferred source to see more of our stories on Google. Guests visting the Lowell Observatory in Flagstaff, Arizona during the I Heart Pluto Festival gaze at celestial objects from the ...

Our definition of a planet has changed over the years — causing a bit of confusion. | Credit: wasan prunglampoo/Getty Images Over the past 250 years, the number of "planets" in our solar system has ...

The solar system consists of our star, the sun, and everything bound to it by gravity: the planets Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune, along with dwarf planets like ...

When I was a kid, there were nine planets. Now we know of thousands! But that includes exoplanets, alien worlds that orbit alien suns. Only eight planets call our solar system home. Or there might ...

Until Pluto was downgraded to a dwarf planet (something that still rankles many people), some scientists were of the view there is a tenth planet in the solar system. With the change to the status of ...

Growing up, we learned there are nine planets: Mercury, close to the sun; Venus next; Earth, where we live; the red planet, Mars; the largest planet, Jupiter; Saturn ...

See more of our trusted coverage when you search. Prefer Newsweek on Google to see more of our trusted coverage when you search. Good news for those with a Pluto-shaped hole in their life, as ...

An image of Pluto taken by NASA's New Horizons spacecraft on July 13, 2015. The planet was first discovered by Clyde Tombaugh, who graduated from high school in rural Kansas and went on to earn his ...

Rachel Feltman: For Scientific American’s Science Quickly, I’m Rachel Feltman. Unless you’re really on the low end of our listener age bell curve, chances are you grew up learning about our solar ...

Over the past 250 years, the number of "planets" in our solar system has ranged from six to nine — and, briefly, even 11 — depending on what astronomers knew at the time and how they defined a planet.