Sunset, Solstice & the St. Joseph Lighthouse

Winter Solstice by Scott Glenn

Happy Solstice everyone!

Scott took this photo just after sunset on the winter solstice in 2016 at the St. Joseph Lighthouse​!

See the photo bigger and see many more in Scott’s Lighthouses gallery on Flickr!

Also check out more winter solstice & St Joseph Lighthouse pics on Michigan in Pictures!

Today is not the Earth’s Longest Day

Untitled, photo by Jim Schoensee

The summer solstice arrives at 12:24 AM tomorrow when sun’s zenith is at its furthest point from the equator, making today the longest day of  2017. Vox’s article on the summer solstice has some interesting info about the solstice including a look at whether or not today is the longest day in Earth’s history:

Ever since the Earth has had liquid oceans and a moon, its rotation has been gradually slowing over time due to tidal friction. That means — over very, very long periods of time — the days have been getting steadily longer. About 4.5 billion years ago, it took the Earth just six hours to complete one rotation. About 350 million years ago, it took 23 hours. Today, of course, it takes about 24 hours. And the days will gradually get longer still.

Given that, you’d think 2017 would be the longest day in all of history. But while it’s certainly up there, it doesn’t quite take top honors.

That’s because tidal friction isn’t the only thing affecting Earth’s rotation — there are a few countervailing factors. The melting of glacial ice, which has been occurring since the end of the last ice age 12,000 years ago (and is now ramping up because of global warming), is actually speeding up Earth’s rotation very slightly, shortening the days by a few fractions of a millisecond. Likewise, geologic activity in the planet’s core, earthquakes, ocean currents, and seasonal wind changes can also speed up or slow down Earth’s rotation.

When you put all these factors together, scientists have estimated that the longest day in Earth’s history (so far) likely occurred back in 1912. That year’s summer solstice was the longest period of daylight the Northern Hemisphere has ever seen (and, conversely, the 1912 winter solstice was the longest night we’ve ever seen).

Eventually, the effects of tidal friction should overcome all those other factors, and Earth’s days will get longer and longer as its rotation keeps slowing (forcing timekeepers to add leap seconds to the calendar periodically). Which means that in the future, there will be plenty of summer solstices that set new records as the “longest day in Earth’s history.”

View Jim’s photo of the Charlevoix Lighthouse on the summer solstice in 2010 bigger and see more in his Charlevoix Lighthouse slideshow.

An Ode to the Winter Solstice

an-ode-to-the-winter-solstice

An Ode to the Winter Solstice, photo by Cherie

EarthSky’s page on the winter solstice says:

The solstice happens at the same instant for all of us, everywhere on Earth. In 2016, the December solstice comes on December 21 at 5:44 a.m. EST. That’s on December 21 at 10:44 Universal Time. It’s when the sun on our sky’s dome reaches its farthest southward point for the year. At this solstice, the Northern Hemisphere has its shortest day and longest night of the year.

…At the December solstice, Earth is positioned in its orbit so that the sun stays below the north pole horizon. As seen from 23-and-a-half degrees south of the equator, at the imaginary line encircling the globe known as the Tropic of Capricorn, the sun shines directly overhead at noon. This is as far south as the sun ever gets. All locations south of the equator have day lengths greater than 12 hours at the December solstice. Meanwhile, all locations north of the equator have day lengths less than 12 hours.

For us on the northern part of Earth, the shortest day comes at the solstice. After the winter solstice, the days get longer, and the nights shorter. It’s a seasonal shift that nearly everyone notices.

View Cherie’s photo background big and see more in her Michigan can be a Winter Wonderland slideshow.

Summer Solstice and a Strawberry Moon

Summer Solstice 2013 by Ken Scott

Summer Solstice … 2013, photo by Ken Scott

Today at 6:34 PM EDT, the summer solstice officially ushers in summer. EarthSky shares that the full Strawberry moon tonight for the solstice is the first full moon to fall on the summer solstice since June of 1967 and the Summer of Love.

Back in 2001, NASA’s Earth Science Picture of the Day (<–my favorite photo blog – subscribe!) shared the tale of Eratosthenes, the Solstice and the Size of the Earth:

Calculating the SolsticeIt was near the summer solstice of 240 BC that Eratosthenes, curator of the famed Library of Alexandria and renowned mathematician and geographer, performed his famous experiment in Egypt to calculate the diameter of the Earth. The bottom of a deep well in the city of Syene, Egypt (near the present day Aswan Dam and very near the Tropic of Cancer) was known to be illuminated by the sun directly at mid-day on the longest day of the year (the solstice). But on the same day, a vertical pole in Alexandria, some 800 km to the north, cast a distinct shadow. By measuring the shadow and applying the geometry of a sphere, Eratosthenes calculated the Earth’s diameter with remarkable accuracy. Sadly, the concept of a spherical Earth was lost from common thought for over a thousand years until Christopher Columbus and others proved the fact by sailing west to go east. The background reference image of Egypt and the Nile River is provided by the NASA MODIS instrument.

Sep 5, 2006 – Donald Etz notes: “From reading Jeffrey Burton Russell’s book, Inventing the Flat Earth (1991), I was persuaded that most educated Europeans of Columbus’ time believed the earth is round. The main debate seems to have been over its dimensions. Columbus ventured on his voyage because he believed the earth was much smaller than it is.” -ed

View Ken’s photo of the sunrise on the 2013 summer solstice bigger, see more in his Boat(s) slideshow, and definitely check out kenscottphotography.com to view and purchase his work.

More science on Michigan in Pictures.

 

 

Spires and the Solstice

Spires

Spires, photo by Liz Glass

The Old Farmer’s Almanac shares that winter begins with the Winter Solstice at 6:03 PM EST tomorrow (Sunday, December 21):

Winter inspires both joy and woe. Some people can’t wait for the cooler weather, snow, skiing and ice skating, curling up by a fire, and the holiday spirit. Other people dislike the frigid temperatures, blizzards, and wild weather.

The word solstice comes from the Latin words for “sun” and “to stand still.” In the Northern Hemisphere, as summer advances to winter, the points on the horizon where the Sun rises and sets advance southward each day; the high point in the Sun’s daily path across the sky, which occurs at local noon, also moves southward each day. At the winter solstice, the Sun’s path has reached its southernmost position. The next day, the path will advance northward. However, a few days before and after the winter solstice, the change is so slight that the Sun’s path seems to stay the same, or stand still. The Sun is directly overhead at “high-noon” on Winter Solstice at the latitude called the Tropic of Capricorn. In the Northern Hemisphere, the solstice days are the days with the fewest hours of sunlight during the whole year.

Definitely check out Liz’s photo bigger and see more in her massive & cool Ice slideshow or (if you prefer) her Abstracts slideshow.