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Timekeeping and Calendars


Astronomical Firsts June 10, 2010

Radio Programs

September The seventh month becomes the ninth September 1, 2023

Blue Moon A case of the blues for the full Moon August 30, 2023

New Moon The first day of a new month August 15, 2023

Moon and Saturn Timely questions about the Moon May 12, 2023

Daylight Saving Time Springing into Daylight Saving Time March 11, 2023

Moon and Regulus Marking the rhythms of the sky March 5, 2023

The New Year New Year’s Eve celebrations and decorations December 31, 2022

Autumn Marking the dates of the equinox September 22, 2022

Klementinum Tower Climbing toward the stars August 28, 2022

Dog Days The “dog days” of summer August 7, 2022

A New Year “Shouldering” the burden of a new year July 1, 2022

Leap Seconds Minor resets for the world’s clocks June 30, 2022

February Sandwiching in a short month February 1, 2022

Earliest Sunsets Early sunsets for much of America December 5, 2021

September Equinox II Changes in the changing seasons September 23, 2021

Far From the Sun The changing rhythms of the Sun July 3, 2021

Summer Solstice The land of the midnight Sun June 20, 2021

Vernal Equinox Calibrating the seasons March 19, 2021

Ides of March A date to be wary of March 15, 2021

Christine Kirch Getting paid to make calendars February 28, 2021

Groundhog Day Thinking about the seasons February 2, 2021

Saturnalia A planet and a party share a name December 17, 2020

Shorter Days The days keep getting longer July 30, 2020

Seventh Month A new name for the seventh month July 1, 2020

Keeping Time III Marking the beat of a second May 29, 2020

Keeping Time II Clocks that tick at different rates May 28, 2020

Keeping Time Keeping time for everyone May 27, 2020

Leap Day Leaping across the days February 29, 2020

Celebrating Spring “Springing” a seasonal tradition February 1, 2020

New Year’s Eve A bright start to the new year December 31, 2019

Time Balls Keeping time with the drop of a ball December 30, 2019

Friday the 13th The story behind an “unlucky” day December 13, 2019

Falling Back Recouping an hour of sleep November 2, 2019

Dog Days The Dog Days of summer August 17, 2019

Oddest Month The oddest month comes to an end February 28, 2019

Groundhog Day Celebrating Groundhog Day February 2, 2019

Standard Time Falling into Standard Time November 3, 2018

Nabta Calendar markers in the Egyptian desert June 20, 2018

Moon and Spica A star with an important history May 25, 2018

Martian Autumn A new season for the Red Planet May 22, 2018

Groundhog Day Lighting the coming spring February 2, 2018

Summer Solstice Marking time by the motions of the Sun June 20, 2017

Sunrise and Sunset Defining the day’s “bookends” June 17, 2017

Daylight Saving Time Springing into a new time March 11, 2017

Groundhog Day Shadow or sunlight for a famous rodent February 2, 2017

February The oddest month of the year February 1, 2017

Featured Images

Dog Days August 7, 2022

Shorter Days July 30, 2020

1881 Boston time ball

Time After Time December 30, 2019

Time machines

Time to Ponder September 20, 2019

Twilight over McDonald Observatory

A Civil Sky June 18, 2017