🚀 go-pugleaf

|>> >Forwarded from:
|>> >PUBLIC INFORMATION OFFICE
|>> >JET PROPULSION LABORATORY
|>> 
|>> 
|>> >     Today Mars Observer is about 4.5 million kilometers (2.6
|>> >million miles) from Earth, traveling at a speed of about 10,800
|>> >kilometers (7,600 miles per hour) with respect to Earth.  The
|>> >spacecraft is traveling at a heliocentric velocity of about
|>> >119,000 kilometers per hour (74,000 miles per hour).
|>> 
|>> 
|>> Only 7,600 mph relative to Earth? Is that right? That's not even escape
|>> velocity (~25,000 mph). I also can't think of a way for the craft to be
|>> going 7,600 mph relative to Earth, and 74,000 mph relative to the Sun.
|>> Can someone clear this up for me?
|>> 
|>>                                                       Tom

Gabe (nahigian@athena.mit.edu) writes:

>    Remember that the Earth is also moving pretty damn fast in relation to the
> sun!!

By moving relative to the sun, I think they mean speed towards, or away from
the sun, not around the sun. So the Earth would only be slightly moving 
relative to the sun because of its elliptical orbit. Either way, the space
probe is still said to be moving a fraction of Earth's escape velocity.

                                                          Tom