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Re: Sauropods vs. Gravity - Jim

In a message dated 3/4/02 10:38:29 AM Eastern Standard Time, 
mbonnan@hotmail.com writes:

> I'm curious, though -- why do we weigh so much less on the moon or Mars?  

Because they are less massive than the earth.  If the moon or Mars had the 
same mass as the earth, and their current sizes, we would weigh more on those 
bodies than on the earth.

>  I 
>  understand that mass is not the same as size, but are planets like Venus 
>  Mercury more "massive" than the Earth (you said they move faster in their 
>  orbits)?  Than the moon and Mars?

The orbital velocity of an orbiting body depends on the mass of the object at 
the center of the system (in this case, the sun--the greater the mass at the 
center of the system, the faster the revolution) and on the distance between 
the orbiting body and the orbited body (the smaller the distance, the faster 
the revolution).  It does not depend on the mass of the orbiting body.

--Nick P.