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View Full Version : Terminal Madness question



bdloving
2003-Sep-10, 02:19 PM
So, is there actually anywhere in the universe that the Orion constellation
could be seen in reverse? A tourist stop for the FTL crowd. :)

Donnie B.
2003-Sep-10, 09:19 PM
I'd say almost certainly not.

The reason is that Orion, like all constellations, has a third dimension -- that is, the distances to its stars varies considerably. At the same time, the absolute brightness of those stars also varies. Some are close to us but not inherently bright, others are far away but much brighter. So if you looked at Orion from the "far side", it wouldn't look anything like Orion.

Let's say that you traveled straight through the center of Orion until you were as far beyond its farthest major star as the Earth is from the nearest major star. But now the stars that are close to Earth are very distant, and thus very dim. Those might not be naked-eye visible at all, and there would be other stars, too dim to be seen from Earth but nearby (and therefore bright) as seen from the "far side", that would destroy the familiar pattern of Orion.

Of course, there are numerous extra-galactic objects within the Orion constellation, and these wouldn't be visible at all from the "far side" -- they'd be behind you as you looked back toward Earth. However, none of Orion's major stars is in this category.