Correcting Scientific Misconceptions: The December Solstice

I am still surprised how many articles on otherwise reputable websites when writing about scientific topics are riddled with errors and have clearly been written by lazy journalists with no knowledge of the subject they’re talking about.

One of the worst examples was an article on the December 2023 solstice which recently appeared on a popular British online newspaper “The Independent”. I’ve put the first part of it here.

—————————————————————————————————————–

As the southern hemisphere celebrates the start of summer, those north of the equator will experience the shortest day of the year, known as the winter solstice. This year, it falls on Friday 22 December, the first day of winter.

The word “solstice” derives from sol, the Latin word for sun, and sistere, which means “to come to a stop or make stand”.

Arriving on the same day across the globe, a solstice occurs when the sun reaches its lowest or highest point in the sky during the year as a result of the Earth’s axis tilting to or away from the sun.

For people who live in the Northern Hemisphere, this Friday will be the one day of the year with the shortest period of sunlight. The solstice will begin on 4:44pm GMT on 22 December, when the Earth is at its maximum tilt, 23.5 degrees, away from the sun.

The solstice also occurs when the sun is directly over the Tropic of Capricorn, which is located “south of the equator and runs through Australia, Chile, southern Brazil, and northern South Africa,” according to the National Weather Service.

—————————————————————————————————————–

Source  https://www.independent.co.uk/life-style/winter-solstice-2023-when-b2468311.html retrieved 22 December 2023

It is truly amazing that such a short article can contain so many statements that are simply wrong. So, let’s have a look at it again.

The article says the solstice “will begin on 4:44pm GMT on 22 December”

WRONG: The December solstice doesn’t begin then, it is an event which occurs at a particular time. The December solstice occurs when the Earth’s North Pole is tilted furthest away from the Sun, which happened at 3:27 AM GMT. the journalists writing this could have easily checked when the 2023 December solstice occurs by checking with a reputable website such as https://www.timeanddate.com/calendar/winter-solstice.html . I wonder where on Earth they got 4:44 pm from!?

If I’m being really picky, in precise writing the term UTC (which stands for Coordinated Universal Time) should be used rather than GMT but I’m probably being too pedantic by mentioning this, because GMT is widely used by the general public.

“Arriving on the same day across the globe, a solstice occurs….”

WRONG The date the solstice falls on depends on the time zone. For example in San Francisco, which is on the Pacific time zone, 8 hours behind UTC, the solstice occurred  at 7:27 pm on December 21.

“The solstice also occurs when the sun is directly over the Tropic of Capricorn”.

This is badly written. The tropic of Capricorn is a line of latitude running approximately 23.44 degrees south. Clearly the Sun cannot be overhead everywhere on a line of latitude at the same time. At some places located  on the tropic of Capricorn it was dark at 3:27 am when the solstice occurred! What it should have said is

 “….at the December solstice, the location where the Sun is directly overhead lies on the tropic of Capricorn”.

“…a solstice occurs when the sun reaches its lowest or highest point in the sky during the year as a result of the Earth’s axis tilting to or away from the sun.“

This is badly written and incorrect. The true situation is more complicated.

For locations which don’t lie at polar latitudes, the Sun reaches its lowest point in the sky twice a day every single day of the year. This happens at sunrise and sunset! I guess what the authors really meant to say is:

 “…at the solstice the Sun reaches either  its lowest maximum elevation (for locations in the Northern Hemisphere) or its greatest maximum elevation (for locations in the Southern Hemisphere)“

However, although this is true for most locations on Earth, it isn’t true for all locations on the Earth. The true position is a little more complicated. I’ve put a summary here.

Latitude	Sun’s maximum elevation	Hours of daylight
Above Arctic Circle	Sun below horizon all day	Zero
On Arctic Circle	Lowest value of the year. Sun briefly just above the horizon	Lowest value of the year (Few minutes)
Between Arctic Circle and Equator	Lowest value of the year	Lowest value of the year
On Equator	Joint lowest value of the year. The June solstice is the other date	All days have same hours of daylight throughout the year
Between Tropic of Capricorn and the Equator	Neither the lowest nor the highest value of the year.	Highest value of the year
On the Tropic of Capricorn	Highest value of the year. Sun directly overhead	Highest value of the year
Between Tropic of Capricorn and Antarctic circle	Highest value of the year	Highest value of the year
On or below Antarctic circle	Highest value of the year	24 hours

If you want to know the detail behind this then watch this video on my YouTube channel 🙂