• Question: is it true that there is a planet nine in our solar system?

    Asked by Frog to Daniel, Hannah, Maggie, Ry, Scott on 8 Nov 2017.
    • Photo: Maggie Lieu

      Maggie Lieu answered on 8 Nov 2017:

      you mean Pluto? XD

    • Photo: Ry Cutter

      Ry Cutter answered on 8 Nov 2017:

      Planet 9 is a theorised planet. Some scientists think there has to be a large object on the outskirts of our solar system to account for the crazy motion of some smaller object called Trans Neptunian Objects (TNOs). Trans Neptunian objects fall under a category of minor planets that go around the sun and are further away than Neptune. The crazy orbits (some think) are a result of a big gravitational field… planet 9’s gravitational field.

      We still haven’t seen the planet and until we do we can’t be certain it is there. It is looking more unlikely as a lot of people have been looking for a while and they’re running out of places planet 9 could be 🙁

      Great Question,

      Ryan

    • Photo: Hannah Middleton

      Hannah Middleton answered on 8 Nov 2017:

      When I was at school, Pluto was planet 9! 🙂

      But yes, people do wonder if there is another planet far out in the solar system, because they can’t quite explain the motion of the other objects in the solar system just like Ryan says. But we have to find it first to prove it!

      Did you know that the existence of Neptune was predicted before it was actually discovered? Astronomers noticed that the planet Uranus was following a slightly different path than expected and concluded that there must be another planet’s gravitational pull at work. A mathematician called Urbain Le Verrier worked out the position of the mystery planet and in 1846 sent his prediction to an astronomer called Johann Gottfried Galle. He then made some observations and found Neptune just where Le Verrier said it would be!

    • Photo: Daniel Williams

      Daniel Williams answered on 8 Nov 2017:

      It’s hard to say for sure, but probably not.

      There are lots of big pieces of rock in the solar system far from the sun. One of those is Pluto, which was known as the 9th planet when I was at school, but astronomers had a rethink when we started discovering a lot of similar objects, and decided that it was silly to have a solar system with dozens of planets.

      Some of the methods which we use to look for gravitational waves can tell us that there are no really big planets which we can’t see for some reason, because their gravity would affect our measurements. The longer we go on looking for gravitational waves the more sensitive we become to those objects!

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