planetary alignmentgreenspun.com : LUSENET : Astronomical_Calculations : One Thread
Is it possible for all nine planets to be aligned including the sun? what about w/the sun and our moon?
-- armin delarmente (firstname.lastname@example.org), March 06, 2001
It all depends on how close an 'alaignment' you want. If you mean all the major planets lying on an actual straight line, I'm not sure that can happen as all the orbits have different inclinations to the ecliptic. If you mean all 9 planets within (say) 3 degrees of sky as seen from the Sun , then perhaps, but very rare.
A good article on this one might be
Jean Meeus (who writes the standard textbook on astronomical calculation for amateurs) lists a number of planetary groupings and the range of longitudes during the groupings.
-- Keith Burnett (email@example.com), March 06, 2001.