• Question: What is the lightest known planet in the universe

    Asked by 13marbles to Adam, Chris, Eleanor, Jessamyn, Sinead on 11 Nov 2013.
    • Photo: Adam Murphy

      Adam Murphy answered on 11 Nov 2013:

      In the whole universe? I don’t know

      But it would probably be something like Saturn but without the rings.

      Saturn in 95 times bigger than Earth, but it’s almost all just made of liquid hydrogen, and hydrogen is the lightest element there is.

      In fact, if there was an ocean big enough to hold it, Saturn would float in water!

      I’m really curious to see what the people looking for new planets find!

    • Photo: Eleanor Holmes

      Eleanor Holmes answered on 13 Nov 2013:

      It’s definitely going to be a gaseous planet. The weight of something depends on it’s volume and it’s density. Hydrogen and Helium are the lightest elements so any planet we find that is composed primarily of Hydrogen and Helium gas is going to be very light compared to their carbon and iron brothers. After that it’s a matter of volume. So if we find a Saturn-like planet, without rings that has a smaller diameter we can conjecture that it to be very light.

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