Re: [Phys-L] planetary alignment

[Richard Bowman <rbowman@bridgewater.edu>]

Anthony, the best source I have found for synodic periods of the
planets (that is, the time it takes for the planet and Earth to be
back in the same relationship with respect to the Sun), is:
   http://nssdc.gsfc.nasa.gov/planetary/planetfact.html
Alex William at Princeton has compiled a lot of planetary data but not
the synodic periods.
   http://www.princeton.edu/~willman/planetary_systems/Sol/
William updated his page as of September 2012 while NASA did it as of
2006, so Williams' data may be more up-to-date.

Richard L. Bowman
Prof. of Physics, Emeritus
Bridgewater College, VA, USA

On Tue, Jun 25, 2013 at 11:00 PM, Anthony Lapinski
<Anthony_Lapinski@pds.org> wrote:
> In the Mechanical Universe video, Navigating In Space, they discuss how
> spacecraft are sent to the planets. When the Earth and a planet are
> aligned, it's called an opportunity. For example, Mars has to be 44°
> ahead of the Earth when this happens so that the craft can land on Mars
> along a low-energy trajectory that intersects the orbits of Earth and
> Mars. This opportunity happens about every two years. For Venus (-54°),
> once every 19 months. And for Jupiter (97°), once every 13 months.
>
> On a related note, I am wanting to know how often each planet is closest
> to the Earth. Then it will appear largest (and brightest) in the sky. For
> example, Jupiter's orbital period is 11.86 years. If Jupiter and the Earth
> are at their closest position tonight, how long will it be until they
> return to this closest position again?
>
> Is there a simple formula to figure this out (given two different orbital
> periods)? Or does anyone know of an online source that shows/calculates
> this?
>
>
>
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