Re: [Phys-l] Lagrange points

["John M Clement" <clement@hal-pc.org>]

Ah, but in a rotating frame there is a third "pseudoforce" and the 
Earth and the Sun do not balance each other.  The big problem here is 
that the writing is for the general public, and one must present the 
situation in a proper Newtonian fashion.  Considering that most 
readers have a very hazy idea of physics, the explantion needs to be 
at least that the gravitational force of the Earth slightly balances 
that of the Sun so that the satellite be in an orbit which is 
sycronized with the Earth's orbit.  But stating the gravity balances 
is playing into a major misconception, which the author may even have. 
We MUST be hard on major misconceptions when they appear in popular 
publications.  Presumably they should never appear in scientific 
reports and journals.

John M. Clement
Houston, TX


 John Mallinckrodt <ajm@csupomona.edu> wrote:
> I wouldn't be too hard on them.  It's not at all unreasonable to 
> work  
> in a rotating frame when thinking about things like Lagrange points. 
>  
> Moreover, notice that they didn't even talk about gravitational  
> *forces*.  They simply said, "the gravity of the Earth and sun  
> balance out."  That's really not all that far from a completely  
> reasonable general relativistic statement.
>
> John Mallinckrodt
> Cal Poly Pomona
>
> On Dec 2, 2009, at 6:39 PM, John Clement wrote:
>
> > I recently read an article about scientific innovations in the  
> > recent Time
> > magazine while waiting in the optometrists orbit.  One innovation  
> > was an
> > infrared observatory which is stationed at a Lagrange point where 
> > the
> > "Earth's gravitational force balances the sun's".
> >
> > So I checked online and came up with a hit on the Brittanica
> >
> > http://www.britannica.com/EBchecked/topic/524909/satellite-observatory
> > " the Solar and Heliospheric Observatory (SOHO; 1995) was  
> > maneuvered to the
> > vicinity of a gravitational balance point (L1, one of the Sun-Earth
> > Lagrangian points)"
> >
> > The Wikipedia explains the Lagrangian points correctly!
> >
> > Where are the scientific proofreaders?  The writers would fail the 
> > FCI
> > because they don't seem to know that when the forces balance the  
> > object goes
> > in a straight line and will NOT orbit.
> >
> > John M. Clement
> > Houston, TX
> >
> > _______________________________________________
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>
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