Marilyn Misses the Satellite

Marilyn is Wrong Copyright © 1997-1998 Herb Weiner. All rights reserved.

Ask Marilyn ® by Marilyn vos Savant is a column in Parade Magazine, published by PARADE, 711 Third Avenue, New York, NY 10017, USA. According to Parade, Marilyn vos Savant is listed in the "Guinness Book of World Records Hall of Fame" for "Highest IQ."

In her Parade Magazine column of January 12, 1997, Marilyn claims that a geosynchronous orbit comes fairly close to allowing a satellite to be "parked" in longitude (east/west) over a place like New York City, but that the satellite moves up and down in latitude (north/south) over the course of a day.

Are your sure about this, Marilyn?

Charlie Kluepfel <> wrote:

Marilyn says the questionor is more right in saying a satellite cannot be parked over say New York city as it can only be parked over the equator, than someone who claims that a satellite can be parked over New York City. She goes on to say that a satellite can be parked over NYC in the sense of maintaining the same longitude as NYC, but will vary in latitude.

One of her statements is factually wrong: a satellite that moves north and south, and at the northern end passes over NYC, will actually perform a figure-8, similar to the analemma that is/was printed on globes showing the noontime position of the sun. There is no way that strict north/south motion can be maintained in a straight line over one meridian.

Conceptually, the writer is not just more right, but completely right. A satellite that, as seen from NYC, varies from being directly overhead to being 8 or 9 degrees above the horizon is in no way "parked over NYC", and in fact the stationary satellite over the equator, staying 49 degrees up as seen from New York, is a preferable orbit for anyone wishing to beam signals to NYC than one that goes nearly to New York's horizon.

I wrote a program to figure out how far such a satellite would wander in longitude. If it were in an orbit that took it directly over latitude 41 north at its northernmost (and therefore 41 south at its southernmost) it would wander +/- 8 degrees in longitude from its intended 74 degrees west, thus ranging from 66 degrees west to 82 degrees west. This assumes a circular orbit; any eccentricity would cause the maximum displacement in longitude to be even greater.

Everyone is Wrong!

GE Wagner <> claims that Marilyn, Charlie, and the writer are wrong:

You can park a satellite over New York if you follow the definition of "park over" as defined by Webster's Ninth New Collegiate Dictionary and stop assuming things that weren't stated.

So in our case, "parked over" means to establish in orbit in a position higher than or above New York. (My wife the professional English editor assures me that the context of the writer's statement is that the satellite's position be unchanging relative to its angle to New York.)

You can park a satellite over New York if you follow these four rules:

Everyone is Wrong Again!

RM Mentock <> also claims that everyone is wrong:

Because the Earth's shape has a quadrapole component (the equator is an ellipse) there is a small tendency for geostationary satellites to drift, oscillating about one of two points that are above the nodes of this ellipse. Even geostationary satellites need adjustments to counter this effect, though they do need less station-keeping than other satellites. (For that matter, a satellite can be parked anywhere if you have enough fuel and a powerful engine.) The longitude of New York is not one of the two points. last updated June 30, 1998 by