In the early Church, there was no fixed date for the celebration of Christmas across the entire Church, or even agreement as to when Jesus was born.
The main reason early Christians chose December 25th for the date of Christmas relates to two dates that were bandied about: the date of the creation of the world, and the vernal equinox. According to some early writers, both events happened on March 25th. Early Christian writer Sextus Julius Africanus (220 AD) speculated that the world was created on March 25th, based on his chronology of Jewish and Christian history, contained in his Chronographia.
Julius Africanus suggested that Christ became incarnate on that date; this makes perfect symbolic sense, since at the Incarnation, the new creation began. Accordingly, since the Word of God became incarnate at His conception, this meant that, after nine months in the Virgin Mary’s womb, Jesus was born on December 25th. The Emperor Constantine (d. 337 AD) encouraged Christians to replace the winter solstice festivals, especially that of Sol Invictus (the unconquered sun), with the Christian festival, using the play on words of Filius Invictus (the unconquered Son of God) which had been speculated about somewhat convincingly for that time by Julius Africanus.
Pope Liberius codified Christmas to be celebrated on Dec. 25th; however, there were Christmas liturgical celebrations in Rome as early as 336, one year before Constantine’s death.
With all this history in mind, I have been doing some astrophotography of Sol Invictus, our sun. The first image is of flares taken with my H-alpha telescope and IS 41 camera on 12-12-12, running through an avi file of 900 images to sort out the best of the group. The sun is washed out in order to bring out the flares (or prominences).
The second image, also taken on 12-12-12, is one of surface sun spots (lighter patches) and plasmas (darker trails). It is cropped and artificially colored to reflect the orange-red color of the sun. Sunspots do not appear in random locations. They tend to be concentrated in two mid-latitude bands on either side of the equator. They begin appearing around 25 to 30 degrees north and south of the center. As the solar cycle progresses, new sunspots appear closer to the equator. My image below appeared south of the sun’s equator.
It takes approximately eleven years for the sun to move through the solar cycle that is defined by an increasing and then decreasing number of sunspots. As it reaches the close of a cycle, new sunspots appear near the equator, while a new cycle produces sunspots in higher latitudes. The cycles overlap; sunspots from the previous cycle can still develop even after sunspots from the new cycle appear. So solar scientists have a very difficult time saying exactly when one cycle ends and the next begins.
As of early 2011, solar cycle 24 was under way, headed toward a peak of activity expected in 2013.
Our sun burns several hundred million tons of hydrogen per second, converting it to helium by nuclear fusion. This the source of the sun’s energy, and if the sun were consuming gas at less than this rate, then we would not get the required warmth to support life. However, there is no cause of alarm, because there is a HUGE amount of hydrogen in the sun.
The Romans and other older cultures had it almost right. The sun is, for now, Sol Invictus.