Christmas comes early for skywatchers this year.

A special full lunar eclipse will take place early Tuesday morning and thanks to a number of variables, the moon will be high in the sky and will appear blood red.

Tuesday morning’s celestial event will mark the first time a total lunar eclipse has taken place on Dec. 21 -- the Winter Solstice -- since 1638.

The eclipse should start around 1:30am (ET) Tuesday morning and is expected to last about three-and-a-half hours. The moon should appear bright red by about 2:41am.

During a lunar eclipse, the moon passes through a shadow created by the Earth that block’s the sun’s rays. Indirect sunlight will still illuminate the moon and the orb will also have a special glow thanks to its position in the sky, which places it in line with the stars of the Milky Way.

The moon will be high in the sky because the eclipse in falls on the Winter Solstice -- the shortest day of the year -- and it will appear darker in colour this time due to large amounts of volcanic ash in the atmosphere.

Ottawa’s forecast of a clear sky for Tuesday morning will mean a good view of the event, however some cloud is expected over Toronto.

Lunar eclipses are safe to watch with the naked eye. Two will happen in June and December of 2011, although only the latter will be partially visible in North America.

NASA's Lunar Eclipse page