Expert: Courtney Seligman - 2/10/2009

Question
QUESTION: One story in Hindu Mythology was saying there was an
astrological event of all the planets & Sun came on a
straight line in the space around more than 3000 thousand
years back in the history!  Could you please explain the
possibility of this statement whether true of false?

ANSWER: Sorry for the delay in answering, but I just got back from the hospital, and didn't receive your question until a few minutes ago.

It is conceivable, if by "all the planets" you mean all the ones known to the ancients, that they could have more or less lined up on some past (or will do so on some future) date. It only takes 20 years for Jupiter to line up with Saturn, and because of a close relationship between the orbital period of each planet with the next, the inner planets would have a small chance of lining up with each other at whatever time Mars passed Jupiter and Saturn.

It's not likely that such an alignment would put the various planets within, say, 30 degrees of a straight line at even the 'closest' alignment in 3000 years, but I don't believe there is anything that would rule out that possibility.

Whether such an alignment would have any meaning is another matter. Because they have relatively small masses (save for Jupiter and Saturn), and are far apart by any Earthly standard, such passages would produce minimal changes in their orbits, and what changes would occur would be nearly identical to those which occur when any of them passes any of the others. Having them all lined up would not make any difference in the overall gravitational dynamics.

Also, no such alignment could have ever been observed by the ancients, because at such an alignment, the two inner planets would be in line with the Sun, and hidden from our view by its glare. It might be possible to say from observations before and after the fact that they were aligned at some intermediate date, but it would be a strictly theoretical calculation, not an actual observation.

Finally, such alignments would have no effect on conditions at the surface of any planet, as their small sizes and great distances make their tidal effects on each others' surfaces hundreds of thousands of times smaller than the everyday tides caused by the Sun and Moon.

To summarize, the statement could be true, though I have no practical way to verify whether it is; but even if it were, it would be only an interesting historical oddity, and of no physical significance.

Courtney Seligman
Professor of Astronomy
Long Beach City College

---------- FOLLOW-UP ----------

QUESTION: Dear Sir,
We have now clear knowledge about each planets in details.  
So according to that can we have a clear idea about the
placements of each planets at any particular day or period
in the past or in the future with the use of a computer
simulation program or by calculation?  So do you think
either NASA or any other institution could able to say
whether such an alignment had taken place there or not
before 3000 years back? I am not concerned about the
physical significance.  I need to refer the matter again
and able to inform you the exact year and date of the event
says in the Mythology. (will write you again)

Answer
I've done a check of famous planetary alignments, and thought you'd be interested to know that ancient Chinese calendars are thought to be based on an apparent alignment of the Sun, Moon and naked-eye planets about 4000 years ago. On the mornings of March 2 through March 5, 1953 BC (extending the Julian Calendar backwards from its inception), the Moon swept past all five naked-eye planets, then the Sun, being a thin crescent in the pre-dawn sky on the 2nd and 3rd, then disappearing as it approached new moon, on the 5th. The planets would not have all been in a line which included the Sun, for if they had been, they wouldn't have been visible; but a nearly straight line went through them, the Earth, and the Moon, just off to the west of the Sun, allowing the six non-solar 'planets' to appear within a few degrees of each other in the pre-dawn sky.

Courtney Seligman