ASTR 310 Lecture Notes - Lecture 2: Regolith, The Moons, Angular Distance
21 Jul 2018
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Document Summary
It is difficult to define the term planet due to our limited scientific data. We are only able to observe the bodies that orbit one star (our sun) and take their properties into consideration as to what defines a planet. To further complicate things, each planet is unique and does not necessarily behave the same as the other planets. With the discovery of extrasolar planets, it may be possible to study other star/planetary systems and generalize what we know about planets to have a more complete definition. As we will see in the next question, the number of planets can change based on how we define a planet. Neptune overlaps and is not predicted by bode"s rule. Neptune are sizeable enough to be considered planets. According to the appendix data on page 392, mercury is too small to be a planet and so is pluto. However, we have additional planets, since the size of certain satellites exceeds 5000 km.
