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...
The debate about Pluto’s planetary status goes on, even among astronomers. Some argue that Pluto’s official planetary status should be restored. They suggest that the requirement that a planet must “clear” other objects from orbit doesn’t make sense—and that there are plenty of examples....
On this basis alone, people like Stern have said, Pluto should be considered a planet since it is a dynamic place, a place that is not so static that only micrometeorites disturb its surface. Views of Charon, Pluto's moon, also show a very dynamic place, including a red cap on its ...
Since 2006, Pluto, once the ninth planet in our Solar System is not classified as a planet. Here’s why. The reason why Pluto is not classified as a planet On August 24, 2006, an IAU resolution created an official definition for the term “planet”. According to this resolution, there...
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. ...
It needs to have enough gravity to pull itself into a spherical shape –Pluto…check It needs to have “cleared the neighborhood” of its orbit –Uh oh. Here’s the rule breaker. According to this, Pluto is not a planet. What does “cleared its neighborhood” mean? As planets form, th...
And so, Pluto is a dwarf planet. There are still many objects with similar size and mass to Pluto jostling around in its orbit. And until Pluto crashes into many of them and gains mass, it will remain a dwarf planet. Eris suffers from the same problem. It's not impossible to imagine...
1269why PlUtoisnota PlanetneildeGraSSetySonHere’s the story of how Pluto lost its planetary status and was demoted to an iceball in the outer solar system. It’s also about my role in this at the Rose Centerfor Earth and Space at the American Museum of Natural History.In building the...
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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 ...