By the time you read this, the December solstice may already have happened. It comes on December 22, 2015, at 4:48 Universal Time. That’s 10:48 p.m. on December 21, for those in the central time zone in North America. It’s when the sun reaches its southernmost point for the year. This solstice marks the beginning of the winter season in the Northern Hemisphere, and the start of the summer season in the Southern Hemisphere. And, no matter where you are on Earth, it marks the beginning of your shortest season of the year.
In other words, the shortest season represents the time period between the December solstice and the March equinox. This upcoming season is a touch shy of 89 days.
Contrast the number of days of this upcoming season with that of the longest season: A Northern Hemisphere summer or Southern Hemisphere winter. The longest season as measured from the June solstice to the September equinox lasts 93.65 days. That’s nearly 5 days longer than the duration of time from the December solstice to March equinox.
In early January, the Earth swings closest to the sun for the year. Because Earth is nearest the sun at this time, the Earth moves most swiftly in its orbit. That’s why a Northern Hemisphere winter or Southern Hemisphere summer is the shortest of the four seasons.
On the other hand, the Earth is farthest from the sun in early July. The Earth moves most slowly in its orbit when it’s farthest from the sun. So that’s why a Northern Hemisphere summer or a Southern Hemisphere winter (June solstice to September equinox) counts as the longest of the four seasons.
Lengths of the astronomical seasons:
December solstice to March equinox: 88.99 days
March equinox to June solstice: 92.76 days
June solstice to September equinox: 93.65 days
September equinox to March solstice: 89.84 days
The December solstice ushers in the shortest season. According to the mathematical wizard Jean Meeus, a Northern Hemisphere winter or Southern Hemisphere summer became the shortest season after the year 1246. The astronomical season between the December solstice and the March equinox will reach a minimum value of 88.71 days around the year 3500, and will continue to reign as the shortest season until about 6430.
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John Nelson created this gif using imagery from the NASA Visual Earth team. He calls it A Breathing Earth. Read more about this image.
Bottom line: By shortest season, we mean the time between a solstice and an equinox. Shortest season begins now. It’s a touch shy of 89 days in length.
For the Western Hemisphere, first full moon on Christmas since 1977
EarthSky astronomy kits are perfect for beginners. Order today from the EarthSky store
Donate: Your support means the world to us
from EarthSky http://ift.tt/1J2LEIN
By the time you read this, the December solstice may already have happened. It comes on December 22, 2015, at 4:48 Universal Time. That’s 10:48 p.m. on December 21, for those in the central time zone in North America. It’s when the sun reaches its southernmost point for the year. This solstice marks the beginning of the winter season in the Northern Hemisphere, and the start of the summer season in the Southern Hemisphere. And, no matter where you are on Earth, it marks the beginning of your shortest season of the year.
In other words, the shortest season represents the time period between the December solstice and the March equinox. This upcoming season is a touch shy of 89 days.
Contrast the number of days of this upcoming season with that of the longest season: A Northern Hemisphere summer or Southern Hemisphere winter. The longest season as measured from the June solstice to the September equinox lasts 93.65 days. That’s nearly 5 days longer than the duration of time from the December solstice to March equinox.
In early January, the Earth swings closest to the sun for the year. Because Earth is nearest the sun at this time, the Earth moves most swiftly in its orbit. That’s why a Northern Hemisphere winter or Southern Hemisphere summer is the shortest of the four seasons.
On the other hand, the Earth is farthest from the sun in early July. The Earth moves most slowly in its orbit when it’s farthest from the sun. So that’s why a Northern Hemisphere summer or a Southern Hemisphere winter (June solstice to September equinox) counts as the longest of the four seasons.
Lengths of the astronomical seasons:
December solstice to March equinox: 88.99 days
March equinox to June solstice: 92.76 days
June solstice to September equinox: 93.65 days
September equinox to March solstice: 89.84 days
The December solstice ushers in the shortest season. According to the mathematical wizard Jean Meeus, a Northern Hemisphere winter or Southern Hemisphere summer became the shortest season after the year 1246. The astronomical season between the December solstice and the March equinox will reach a minimum value of 88.71 days around the year 3500, and will continue to reign as the shortest season until about 6430.
Enjoying EarthSky so far? Sign up for our free daily newsletter today!
John Nelson created this gif using imagery from the NASA Visual Earth team. He calls it A Breathing Earth. Read more about this image.
Bottom line: By shortest season, we mean the time between a solstice and an equinox. Shortest season begins now. It’s a touch shy of 89 days in length.
For the Western Hemisphere, first full moon on Christmas since 1977
EarthSky astronomy kits are perfect for beginners. Order today from the EarthSky store
Donate: Your support means the world to us
from EarthSky http://ift.tt/1J2LEIN
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