Courtesy of EarthSky
A Clear Voice for Science
Today is the day of the December solstice – the first day of winter in the northern hemisphere and the first day of summer in the southern hemisphere. At 5:47 p. m. Universal Time (12:47 p. m. Mountain Time) today, the sun reaches its farthest point south of the Earth’s equator, marking the precise moment of this year’s 2009 December solstice. In both the northern and the southern hemisphere, the December solstice brings the southernmost sunrise and the southernmost sunset of the year. In the northern hemisphere, the southernmost sunrise and sunset ushers in the shortest day and the longest night of the year. In the southern hemisphere, it’s the exact opposite. The year’s southernmost sunrise and sunset give the southern hemisphere its longest day and shortest night.
Not everyplace worldwide has a sunrise and a sunset on the day of the December solstice. North of the Arctic Circle – or north of 66.5 degrees north latitude – there is no sunrise or sunset today, because the sun stays beneath the horizon all day long. South of the Antarctic Circle – at 66.5 degrees south of the equator – you won’t see a sunrise or sunset either, but for a totally different reason. South of the Antarctic Circle, the sun stays above the horizon all day. To celebrate the solstice, how about looking at the moon and the planet Jupiter in the southwest sky after sunset tonight? Although the solstice falls on or near December 21 every year, this evening’s pairing of the moon and Jupiter is unique to December 21, 2009.
Written by Bruce McClure