Solar Week - Ask a Question



Come here during Solar Week (next one: March 22-26, 2021) to interact. To post a question, click on your area of interest from the topics below, and then click on the "Ask New Question" button. Or EMAIL or tweet or plant in Answer Garden your question about the Sun or life as a scientist to us -- and watch for it to appear here.  You can also visit our FAQs (frequently asked questions). In between Solar Weeks in October and March, you can view all the archives here.

PrevPrev Go to previous topic
NextNext Go to next topic
Last Post 10/18/2012 8:23 AM by  Paulett Liewer
Why is pluto not a planet
 2 Replies
Sort:
You are not authorized to post a reply.
Author Messages

Anonymous





Posts:


--
10/17/2012 1:53 PM
    Why is pluto not a planet if it is bigger than mercury
    Tags: Pluto, dwarf planet

    Paulett Liewer



    Basic Member


    Posts:113
    Basic Member


    --
    10/17/2012 2:41 PM

    Good question... but there's more to being a planet than just size. Three requirement were set by the International Astronomical Union (IAU) in 2006.for an object to be called a planet:

    The body

    1) Is in orbit around the Sun (or star)
    2) Has sufficient mass to assume hydrostatic equilibrium (a nearly round shape)
    3) Must be gravitationally dominant enough (massive enough) to prevent anything of similar size, barring its own satellites, from floating around the planet. The term that the IAU used was “clearing the neighborhood of its orbit,” which was one of the most important aspects of the definition that was debated

    Mercury meet all three requirements, so it's classified as a planet.
    Pluto meets the first two, but apparently NOT the last one.

    Object that meet the first two (but not the last) are now called Dwarf Planets. The object UB313 ( Xena) is a dwarf planet LARGER than Pluto.


    Paulett Liewer



    Basic Member


    Posts:113
    Basic Member


    --
    10/18/2012 8:23 AM

    I should have caught this sooner: Mercury is much bigger than Pluto. More than twice by diameter and much more by size and mass.

    Paulett

    You are not authorized to post a reply.


    Twitter Feed

    Scientist Leaderboard

    Name # of replies
    Multiverse skin is based on Greytness by Adammer