James Cameron made a change in "Titanic" for its re-release. Twitter

The re-release of James Cameron's 1997 blockbuster, Titanic hits theaters April 4. Fans of the movie might be surprised that Cameron made a change to the ending of the film...a very big one.

According to Movie Talk, the director changed the sky in the re-release. Cameron told UK magazine, Culture, that he changed the sky due to Neil deGrasse Tyson, a leading astronomer in the U.S. The astronomer had reportedly sent Cameron a snarky email, stating that the sky in one of the end scenes with Rose lying on driftwood while she stares is not accurate. In the Atlantic in 1912, that is not the star field she would have seen, Cameron said of the email he received from Tyson. The astronomer had told Cameron that with the director's reputation as a perfectionist, I should have known that and I should have put the right star field in.

Tyson had brought up the error in 2009 when he mentioned the discrepancy at a panel discussion. Worse than it being the wrong sky, Tyson had said, the left half of the sky was a mirror reflection of the right half of the sky! It was not only wrong it was lazy!

The Avatar director told Culture that he emailed Tyson back saying, All right, you son of a bitch, send me the right stars for the exact time, 4:20 a.m. on April 15, 1912, and I'll put it in the movie.

Cameron did just that, changing the sky while Rose lay in the ocean on a piece of driftwood. Let us know if you noticed the difference when you hit theaters to see the re-release of Titanic.