Article: Is Pluto a planet?

Pluto is a small world, only 2,400 km in diameter. Ever since its discovery in 1930, it has been considered the ninth planet. Recently, however, its planetary status has been challenged. Should Pluto be considered a planet? To fully answer this question, we must examine what it even means to be a planet.

Until the 1990s, the subject of what it means to be a planet was not actively considered by scientists. Why? Because the only planets known were the ones in our solar system, and these nine bodies seemed sufficiently different from both smaller bodies (like asteroids and comets) and larger ones (like stars) that there really was no need for a formal definition to ...

Related newspaper, magazine, and journal articles:

 
 
Newsweek Harper's Magazine The Washington Post Chicago Tribune Crain's Chicago Business PRNewswire Pediatric News The Nation Advertising Age The Economist (US) A FREE trial gives you access to over 80 million articles! Access over 6,500 publications with a FREE trial!