• Question: are there other planets we don't know about

    Asked by 328bera39 to Colin, John, Kevin, Shikha, Triona on 10 Nov 2014.
    • Photo: Kevin Motherway

      Kevin Motherway answered on 10 Nov 2014:

      Unlikely in our solar system. Telescopes are pretty good enough to spot something, but more importantly all the gravitational calculations say there’s isn’t another one out there (Uranus and Neptune were predeicted by mathematical calculations before they were found visually). The furthest object after Neptune are Kuiper Belt objects, basically left over building block from the planets. Pluto was downgraded from a plant to a Kuiper Belt Object because there’s dozens of things bigger than Pluto in the Kuiper belt, so its not a planet.

      There are a couple of hundred planets that have been found around stars outside our solar system, so every star you see, it probably unusual if they don’t have a few planets going around them.

      So there are plenty planets out there we don’t know about but we probably have all the ones in our solar system covered…..I think?

    • Photo: Shikha Sharma

      Shikha Sharma answered on 12 Nov 2014:

      hi 328bera39,
      In our solar system there are only 8 planets of sizable mass. Pluto is not considered as planet, rather it is called dwarf planet as it is very small. We have already identified some dwarf planets in our solar system. There is place called Kuiper belt beyond Neptune which is the farthest planet from Sun. We know very well that apart from some dwarf planets, asteroids and comets, there is no sizeable plant in Kuiper belt. Beyond Kuiper belt at extreme outer region of solar system, may be 1 to 2 light years from Sun, It’s certainly possible that there are undiscovered terrestrial planet sized objects out there. There are almost certainly many dwarf planets in the outskirts of our Solar System. From an evidence standpoint, we don’t have any reason to believe there are planets beyond the Kuiper belt, but from a theoretical perspective we don’t have any reason to believe they can’t be there. Who knows? Maybe, one day, we’ll have more than eight planets in our solar system!