This year's winter solstice has just arrived

It is December 21 and winter solstice has arrived. This year it falls at 10:44 GMT (4.14 p.m. Wednesday India time) bringing with it what is conventionally believed to be the longest night of the year.

At the solstice, the sun reaches its lowest altitude of the year before slowly climbing higher and higher with each day.

"Because of the Earth's tilt and the way the planet orbits the Sun, the Sun appears higher or lower in the sky," the Chicagoist quoted Michelle Nichols, a Master Educator at Adler Planetarium Chicago, as saying.

This is the point at which the Sun is at its lowest point in the sky. It is essentially when the Sun is seen directly overhead at the Tropic of Capricorn, Nichols added.

According to The Telegraph, the solstice can happen on December 20, 21, 22 or 23, though December 20 or 23 solstices are rare.

The last December 23 solstice was in 1903 and will not happen again until 2303.

The exact time of the solstice varies each year.

The winter solstice happens every year when the Sun reaches its most southerly declination of -23.5 degrees.

"In other words, when the North Pole is tilted farthest -- 23.5 degrees -- away from the Sun, delivering the fewest hours of sunlight of the year," The Telegraph report added.

The day after the winter solstice marks the beginning of lengthening days,leading up to the summer solstice in June, it added.

--IANS

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