Moviemaker James Cameron has re-edited a scene in Titanic showing stars sparkling in the night sky - after a leading astronomer told him the astral alignment was incorrect.

The director unveiled a 3D version of his multi-Oscar winning classic last month (Mar12) and he resisted the temptation to use its reworking as an excuse to cut scenes he's no longer happy with.

But there was one shot Cameron felt obliged to alter, because a top stargazer informed him the astral pattern onscreen was incorrect for the night the liner sank in 1912.

The scene involves Kate Winslet's character, Rose DeWitt Bukater, drifting on a piece of wood and gazing at the night sky as the disaster unfolds.

Cameron tells British magazine Culture, "Oh, there is one shot that I fixed. It's because Neil deGrasse Tyson, who is one of the U.S.' leading astronomers, sent me quite a snarky email saying that, at that time of year, in that position in the Atlantic in 1912, when Rose is lying on the piece of driftwood and staring up at the stars, that is not the star field she would have seen, and with my reputation as a perfectionist, I should have known that and I should have put the right star field in.

"So I said, 'All right, you son of a b**ch, send me the right stars for the exact time, 4.20am on April 15, 1912, and I'll put it in the movie.' So that's the one shot that has been changed."

