A total lunar eclipse is set to the turn the sky a deep red tomorrow morning as it coincides with the darkest day of the year for the first time in almost 400 years.

The full moon will start to pass through Earth's shadow at 6.32am on the shortest day of the year, the Winter Solstice on December 21.

According to NASA,  the last time a total lunar eclipse coincided with the winter solstice was December 21, 1638 making tomorrow morning the darkest in almost 400 years.