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Retro and distance from earth

Posted: Tue Jul 20, 2010 9:46 am
by junaid
Hello,

Is it true that when a planet is in retro motion its distance from the earth is decreasing and when it is in direct motion, its distance from the earth is increasing?

If yes, then is this universally true or under certain conditions?

Posted: Tue Jul 20, 2010 10:27 am
by Deb
Hi Junaid

No, its not true. Planets are near perigee when they retrograde, but the loop brings them nearer the earth, further from the earth, nearer to the earth again and then further from the earth before they turn direct.

Re: Retro and distance from earth

Posted: Tue Jul 20, 2010 10:48 am
by handn
junaid wrote:Hello,

Is it true that when a planet is in retro motion its distance from the earth is decreasing and when it is in direct motion, its distance from the earth is increasing?

If yes, then is this universally true or under certain conditions?
No, a planet's distance from Earth is decreasing from the moment of its maximum distance, and increasing from the moment of its minimum distance.

The connection between distance and retrograde/direct is that the maximum distance from Earth happens when the planet is direct, and the minimum distance from Earth happens when the planet is retrograde.

And yes, it's true for all the planets, all of the time.

H.

Posted: Wed Jul 21, 2010 12:17 am
by junaid
Hello,

Thnk you both very very much! It's good to see members responding to my, sometimes not so clever, questions!

Thank you again!