Eight Planets
You were probably taught in school that there are nine planets, so recent news with reports of 10, 9, or 8 planets may puzzle you. How many planets are there really? Officially, there are eight planets in our Solar System since Pluto was reclassified as a dwarf planet in 2006. Pluto lost its position as a planet when astronomers discovered an object in the Kuiper Belt larger than the former ninth planet. The discovery of this object, Eris, caused a lot of speculation and upset a lot of assumptions. In summer of 2006, the International Astronomical Union (IAU) had a conference where its members discussed Pluto’s fate. There was a possibility that we could have even ended up with 53 planets – a situation that would have made building a model of the planets in our Solar System a much tougher science fair project. The verdict was that a new class known as dwarf planets was created. The eight planets of our Solar System starting with the one closest to the Sun are Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune.
That does not necessarily mean that it will stay that way though. In an article on the changing number of planets, Kenneth Chang, a science reporter for the New York Times, made it very clear how the number of the planets depends on exactly how we classify an object as a planet. For example, planets were thought to be wandering stars by the Ancients. In more recent times, celestial objects that orbited the Sun were considered planets. Many people are still dissatisfied with IAU’s new classification, so we may see another definition soon.
There will probably be no more planets found in our Solar System, although astronomers have found at least a dozen dwarf planets that are being reviewed by the IAU. Additionally, scientists believe that they have found dozens more celestial objects that will be eventually classified as dwarf planets.
According to official terms, at least for now, there are eight planets in our Solar System, but what about other solar systems? Astronomers can only estimate how many planets are out there, but they are discovering more planets in different solar systems as technology becomes more advanced. So far, they have found several hundred planets orbiting almost three hundred stars, but that is just the beginning of the search. Whether the number of our Solar System’s planets changes again, astronomers are learning more and more about the planets of this Solar System and others every day.
University Today has a number of articles to take a look at including interesting facts about the planets and
If you are looking for more information, check out this article by Kenneth Chang and this one on the planets.
Astronomy Cast has an article about Pluto’s planetary identity crisis.
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