For everyone on Earth, the winter solstice celebrates the shortest day of the year. However, this day does not have the earliest yearly sunsets. They happen to arrive a few weeks before the solstice in the northern hemisphere. If a person lives in the northern hemisphere, he or she would be experiencing the earliest yearly sunsets in the beginning to the middle of December.
This does not seem to make sense. It appears that the earliest sunset should occur on the shortest day to happen in the year. The reason it does not happen is because of something known as a solar noon, or the mid-point of the day. This is the time when the sun is at its highest point in the sky for the day.
In actuality, clocks measure time from one mid-day to the next one, not at midnight like everyone believes. Days are counted off by Earth’s spin, however, they are never exactly the length of 24 exact hours.
So, the precise time of solar noon, when measured by the spin of Earth, changes with the seasons. If one were to take a measurement of one of the spins of the Earth from one midday to the next, it would be discovered that about the time of the winter solstice in December, the actual period of time that is between two sequential solar noon’s would be about half a minute longer than a 24 hour day.
When the clock time is this much later for midday, it also means there will be a later clock time for both sunset and sunrise. This ends up resulting in both earlier sunsets just before the winter solstice arrives and also later sunrises that happen for a couple weeks after the solstice is over.
These dates end up varying with the different latitudes, yet the sequence stays the same. In the northern hemisphere, the earliest sunsets are in early December, then the winter solstice happens and, last, there are the late sunrises in early January.
However, if someone happens to live in the southern hemisphere, he or she should apply almost everything that has been typed here and just apply it to the winter solstice experienced in June.
There are many time differences to deal with as well. The December solstice just happens to occur when Earth is near its perihelion. This means it is at its nearest point to the Sun and also is moving the fastest in orbit. The June solstice is just the opposite. It happens when the Earth is its aphelion, which is when the Earth is at its farthest point away from the Sun. The Earth is also moving around at its slowest orbit in space.
The basis is that the earliest of sunsets and latest of sunrises do not happen on the winter solstice, which is the shortest day of the year.
Speaking of the shortest day of the year, the winter solstice will happen this year in the northern hemisphere at 12:11 p.m. EST on Friday, Dec. 21, 2013. That will be when the Sun is at its most southern point in the sky for the year. This will mark the beginning of winter, and frankly when the sun rises or sets really will not matter for the next couple of months for those living on the northern part of the Earth.
Regardless, the winter solstice celebrates the shortest day of the year and has for thousands of years.
By Kimberly Ruble