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The Question

(Submitted December 07, 1996)

Perhaps you could settle a bet between a friend and me. I would like to know if there has ever been a time when all planets in our solar system were aligned ? Also isn't that supposed to be one of the highlight of the next century when it does happen? My friend at work says it happened recently, as in, in my lifetime. We are 25 and 26. If I remember right it's supposed to be May 5, 2005. Do you know when it will happen? Any response would be much appreciated.

The Answer

Given that the solar system has been around for several billion years, the odds are that the planets have been reasonably well lined up any number of times. There are a number of things to keep in mind, however. First, there is a difference between having the planets aligned with respect to the Sun or as viewed from Earth. If the planets are lined up from the Sun, they also appear lined up from the Earth. If they are lined up from the Earth they need not be lined up from the Sun. Second, there is the question of just how well aligned they are. Perfect alignment is hard. All just being in the sky at the same time is much easier. Anyway, there is software available for you to check it out if you need a more exact answer.

  • This page will give you a map of the solar system for any date you input. (Eg., in June of 1988, all the planets except Jupiter were on the same side of the Sun, and, excepting Pluto, formed kind of a line, as well)
Steve Snowden, Jonathan Keohane and Gail Rohrbach
for Imagine the Universe!

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