The Winter Solstice 2009, the shortest day of the year, takes place today, Dec. 21, 2009.

The Winter Solstice happens when the Earth tilts farthest from the sun and occurs at precisely 12:47 p.m. EST, or 17:47 UTC.

The solstice officially marks the first day of winter and also marks the astrological shift to the sign Capricorn.

The Winter Solstice occurs exactly when the earth’s axial tilt is farthest away from the sun at its maximum of 23° 26′. Though the Winter Solstice lasts an instant in time, the term is also colloquially used like Midwinter to refer to the day on which it occurs.

For most people in the high latitudes this is commonly known as the shortest day and the sun’s daily maximum position in the sky is the lowest. The seasonal significance of the Winter Solstice is in the reversal of the gradual lengthening of nights and shortening of days.

(hat tip to HuffPo)