December 21, 2021

Today saw the annual occurrence of the winter solstice in the Northern Hemisphere.  This year the winter solstice happened on Tuesday, December 21 at 10:59 am EST.  Contrary to popular belief, this is marked by only a moment, and is not a complete day.  Our northern winter solstice can vary in time from December 21 to December 22, and occurs when the Earth’s pole reaches its maximum tilt away from the Sun.  A little before 10:59 am, and the tilt away from the sun is not yet at its maximum.  A little after 10:59 am, and the earth’s tilt has already begun shifting away from its maximum.  While the event ranges across these two days in December, the traditional celebration occurs at sundown on the 21st.  It is on this day and time that the ancients believed the sun “officially” died and was resurrected with the dawn of the 22nd.

When I looked online, I found the winter solstice is also called the hiemal solstice, hibernal solstice, and brumal solstice (all mean relating to or occurring in the winter), and occurs with either of Earth’s poles reaching maximum tilt away from the Sun.  For each respective hemisphere (Northern and Southern), the winter solstice is the day with the shortest period of daylight and longest night of the year, as the Sun is at its lowest daily maximum elevation in the sky.  Either pole experiences continuous darkness or twilight around its winter solstice.  The opposite event is the summer solstice where the respective poles experience continuous daylight or dawn.  Depending on which of the hemisphere’s is in winter solstice, at the Tropic of Cancer or Capricorn the Sun reaches 90° below the observer’s horizon at solar midnight, or to the point of the celestial sphere that is directly opposite the zenith and vertically downward from the observer (called nadir).

The winter solstice occurs during each hemisphere’s winter.  In the Northern Hemisphere, this is the December solstice (usually December 21 or 22) and in the Southern Hemisphere, this is the June solstice (usually June 20 or 21).  Although the winter solstice itself lasts only a moment, the term often refers to the day on which it occurs.  Other names are the “extreme of winter” (Dongzhi), or the “shortest day”.  Since the 18th century, the term “midwinter” has sometimes been used synonymously with the winter solstice, although it carries other meanings as well.  Traditionally, in many temperate regions, the winter solstice is seen as the middle of winter, but today in some countries and calendars, it is seen as the beginning of winter.

Thoughts:  Although the instant of the winter solstice can be calculated, direct observation by amateurs is impossible, but through use of astronomical tracking the precise timing of the solstice is available to the public.  Since we cannot directly detect the precise instant of the solstice, we have marked the observance at a point within the general timeframe (i.e., sundown of the 21st and dawn of the 22nd).  Humans have always found ways to track what is important.  Whether it is the rebirth of the sun for the ancients or number of days until Christmas for a child, and we use this information to make changes in our lifestyle.  With nearly 5.4 million covid deaths in the world and over 800,000 in the US, you would think it might be time to change lifestyles.  Follow the science.  Change is coming and it starts with you.

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