Re: Gravity....Push vs. Pull / Geostationary

Jim Shaffer, Jr. ( (no email) )
Thu, 30 Jul 1998 19:03:29 -0400

> Maybe I'm missing something obvious, but this has boggled me
> for decades. Why do the common satellite TV antennas that point
> towards geostationary satellites always seem to be inclined at
> about 25 degrees up from the horizon -- at least here in
> Southern California (your latitude may vary) ?
>
> There shouldn't be any geosynchronous satellites out in that
> direction -- they should be about 50 degrees from the horizon,
> or ABOVE the half way point to true vertical. This is easy to
> prove if you can do, or imagine, ordinary technical drafting.

Yes, you're missing something obvious. The satellites aren't all located
due south of your home. They're all along the celestial equator (more or
less, allowing for parallax, which is why equinox blackouts don't happen
exactly at the equinoxes), but the celestial equator passes through the east
and west points on your horizon as well as the point due south whose
altitude equals the complement of your latitude. So you could have a dish
pointing due east or due west, though the signal strength would be pretty
poor. These days most commercial TV broadcasts occupy the same one or two
satellites, but in fact there are probably satellites at most of the allowed
orbital positions. (Only a few degrees seperation are necessary for a large
dish. High-power satellites must be further apart since the small dish
doesn't focus as well.)

--"Volleyball is racquetless team ping-pong played with an inflated balland an elevated net while standing on the table." --George Carlin