数十年来，科学家普遍认为太阳系有九大行星，但随着一颗比冥王星更大、更远的天体的发现，使得冥王星大行星地位的争论愈演愈烈。一是由于其发现的过程是基于一个错误的理论；二是由于当初将其质量估算错了，误将其纳入到了大行星的行列。因此在国际天文学联合会大会上，是否要给冥王星“正名”成为了大...
Pluto is not the first “demoted” planet The word planet comes from the Greek planḗtai, meaning “wanderers”. It was used to describe the “wanderers of the sky”, namely the Sun (yes, our star was a “planet” once), the Moon, and five other points of light visible by the na...
Q: Why Is a Pluto No Longer a Planet?Byline: Bill Robertson Brian Diskin In recent years astronomers discovered a number of...Robertson, BillNational Science Teachers AssociationScience & Children
One version of the definition would have actually boosted the number of planets to 12; Pluto was still a planet, and so were Eris and even Ceres, which had been thought of as the largest asteroid. A different proposal kept the total at 9, defining the planets as just the familiar ones ...
One version of the definition would have actually boosted the number of planets to 12; Pluto was still a planet, and so were Eris and even Ceres, which had been thought of as the largest asteroid. A different proposal kept the total at 9, defining the planets as just the familiar ones ...
For a long time, Pluto was considered to be the 9th and tiniest planet in our solar system. However, after scientists made some new discoveries, they decided it really wasn't a planet after all. Come learn about Pluto and why it is no longer called a planet. ...
When Pluto was "demoted" from a planet to a dwarf planet back in 2006, it was a sore subject for many. Then, in 2015, a spaceship gave us our first-ever close-up of Pluto. Read why Pluto is no longer a planet, how it got its name and more cool facts.
Researchers had to ask themselves these questions: If Pluto was a planet, then did that mean Eris was one as well? What about all those other icy objects out in the Kuiper belt, or the littler objects in the asteroid belt? Where exactly was the cut-off line for classifying a body as...
Why is Pluto no longer a planet? The main event of the 2006 General Assembly of the IAU, the proposal that would come to demote Pluto, was a defining moment for the rest of thesolar systemas well. Fiercely debated by the members of the union, the resolution that was passed officially ...
If you want to learn more about this topic, use the lesson Why is Pluto Not a Planet? - Lesson for Kids. This lesson: Discusses why Pluto was once considered a planet Provides facts about Pluto Notes when Pluto was discovered Reveals a discovery made beyond Pluto in 2003 ...