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Solstices and Equinoxes

The solstice is an event in the Earth’s orbit during which the tilt of the Earth’s axis is pointed most directly towards or away from the Sun. The summer solstice for the northern hemisphere occurs within a few days of June 21 every year. It is on this day that the position of the Sun in the sky at noon is at its highest altitude of the year, and the position of the Sun at Sunrise and Sunset is farthest north for the year. The winter solstice is around December 21, marking the date on which the Sun is lowest in the sky at noon and rises and sets farthest south. The day of the summer solstice is the longest day of the year, and the day of the winter solstice is the shortest day of the year. The equinox is the time of year when the Sun appears in the sky at the intersection of the ecliptic and the celestial equator. Two such points exist: The vernal equinox (approx. March 21) marks the start of spring. The autumnal equinox (approx. Sept. 20) marks the start of autumn. At each of these points, the Sun rises due east and sets due west.

Radio Programs

Vernal Equinox Springing into a new season March 19, 2017

Winter Solstice Winter and the laws of planetary motion December 20, 2016

Earliest Sunsets The year’s earliest sunsets December 1, 2016

Autumn Skies New stars for a new season September 22, 2016

Summer Solstice The Sun comes to a standstill June 20, 2016

Beltane Chasing away the winter darkness May 1, 2016

Vernal Equinox A celestial starting point March 19, 2016

September Equinox Changing seasons — one way or another September 21, 2015

Lammas Splitting the difference on the calendar July 31, 2015

June Solstice Celebrating the June solstice June 20, 2015

Spring Equinox Springing into a long, long day March 19, 2015

Earliest Sunsets Stretching out the sunsets December 14, 2014

Rising Ram A faint but famous constellation November 14, 2014

Autumnal Equinox One way to mark a change in seasons September 21, 2014

Spring Equinox Projecting the spring equinox March 19, 2014

Winter Solstice Drawing up the winter solstice December 20, 2013

Spring Springing into a new season March 18, 2013

Summer Solstice Lining up the summer solstice June 19, 2012

Sun Tower A moment of sunlight without shadows June 18, 2012

Spring Equinox A new season and a new beginning March 18, 2012