Four natural divisions in weather and daylight throughout the year resulting from Earth's yearly revolution around the Sun and the tilt of Earth's axis. The seasons are Spring, Summer, Fall, and Winter.

Radio Programs

September Equinox Changing seasons — one way or another Tuesday, September 22, 2015
Lammas Splitting the difference on the calendar Saturday, August 1, 2015
Earth at Aphelion Stretching out the summer Sunday, July 5, 2015
Latest Sunsets Stretching the afternoon sunlight Friday, July 3, 2015
Martian Spring Wild seasons on the Red Planet Thursday, June 18, 2015
Spring Equinox Springing into a long, long day Friday, March 20, 2015
Winter Solstice Tilting back for the start of winter Sunday, December 21, 2014
Earliest Sunsets Stretching out the sunsets Monday, December 15, 2014
Mars at Perihelion Mars gets close to the Sun Saturday, December 13, 2014
Autumnal Equinox One way to mark a change in seasons Monday, September 22, 2014
Mars and Saturn A new season for the Red Planet Thursday, August 21, 2014
Summer Solstice Plotting the motions of the Sun Friday, June 20, 2014
More Moon and Mars A planetary deepfreeze Saturday, June 7, 2014
Getting Close Snuggling close to two giants Friday, January 3, 2014
Watery Skies Casting off into the Celestial Sea Tuesday, October 22, 2013
Venus and Antares Losing a “summer” star Wednesday, October 16, 2013
Moon and Companions Warming up a Martian hemisphere Monday, September 30, 2013
Autumn Nodding away from the Sun Sunday, September 22, 2013
Dog Days The “dog days” of summer Saturday, August 17, 2013
Water Carriers Starry vessels in the midnight sky Thursday, August 8, 2013
Distant Sun Moving away from the Sun Friday, July 5, 2013
Summer Lining up the summer solstice Thursday, June 20, 2013
Spring Springing into a new season Tuesday, March 19, 2013
Fire and Ice Fire and ice in the sky Tuesday, January 1, 2013
Earliest Sunset Stretching out the December sunset Sunday, December 16, 2012
Summer Markers Two summer stalwarts disappear Sunday, October 21, 2012
Dog Days Sweating through the Dog Days of summer Monday, August 6, 2012
Cygnus A “snowbird” that heads west instead of south Monday, July 30, 2012
Distant Sun Slipping away from the Sun Wednesday, July 4, 2012
Summer Solstice Lining up the summer solstice Wednesday, June 20, 2012
Moving Clouds Clouds that move with the seasons Sunday, May 6, 2012
Moon, Saturn, and Spica Bracketing the horn of the dragon Friday, April 6, 2012
Summertime The good old summertime Friday, March 30, 2012
December Solstice A pale light in the daytime sky Wednesday, December 21, 2011
Harvest Moon Balancing the Harvest Moon Sunday, September 11, 2011
Summer Solstice Hot times in northern climes Tuesday, June 21, 2011
Earliest Sunrise Getting ready for some early sunshine Sunday, June 12, 2011
Vanishing Orion A seasonal marker disappears Sunday, May 1, 2011
Spring Equinoxes The start of spring on two worlds Sunday, March 20, 2011
February Counting up the days of February Tuesday, February 1, 2011
Earth at Perihelion Soaking up some extra sunlight Monday, January 3, 2011
Winter Solstice Marking the start -- or middle -- of winter Tuesday, December 21, 2010
Hunter's Moon Hunting up some extra moonlight Friday, October 22, 2010
Earth at Aphelion Our "eccentric" orbit around the Sun Monday, July 5, 2010
Summer Solstice Lighting up the start of summer Sunday, June 20, 2010
Uranus Changing seasons on a giant planet Tuesday, June 1, 2010
May Day Middle of spring or beginning of summer? Saturday, May 1, 2010
March Ram March goes out like a grown-up lamb Saturday, March 27, 2010
Saturn at Opposition A long season under the Sun Sunday, March 21, 2010
Spring Equinox Mapping out the seasons Friday, March 19, 2010
Moon and Spica Reaping a celestial bounty Tuesday, March 2, 2010

Featured Images

Earliest sunsets in December
Early Sunsets Monday, December 15, 2014
Endeavour Crater, winter home of the Opportunity Mars rover
Winter Wonderland Thursday, January 26, 2012
Western sky a couple of hours after sunset in late December
Happy Holidays! Saturday, December 25, 2010


Aries, the Ram Aries, the ram, is a faint pattern marked by...


©2015 The University of Texas McDonald Observatory