• Question: How far away is pluto ?

    Asked by pinkyypinkssz to Keith, Emma on 23 Jun 2010 in Categories: .
    • Photo: Keith Brain

      Keith Brain answered on 23 Jun 2010:

      Pluto (a “dwarf planet”) has a very “eccentric” orbit, so its distance from the sun varies a lot. Given that the earth is also moving, this means that the distance between the earth and Pluto changes in a rather complex way.

      However, the web is an amazing place, and it seems that there is an online orrery that will give you the precise distance to any of the planets at any time (http://www.fourmilab.ch/solar/; or more directly http://www.fourmilab.ch/cgi-bin/Solar/action?sys=-Sf). For example, I checked it at:

      2010-06-23 17:17:11 (this is in Greenwich mean time, not Summer time)

      and found that this distance was:

      30.842 AU

      Now the “AU” (Astronomical Unit) is the mean distance between the earth and the sun, which is about 93 million miles, so this means that Pluto is currently about 2.9 billion miles away!

      PS: If you’re ever near the Science Museum in London, they have a great collection of historical Orreries (I had to check the spelling of that one!).

Comments