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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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