According to the Julian calendar, tonight is the eve of the new year. Most of the world uses the Gregorian calendar, but it was used for over 16 centuries. (The Christian Eastern Orthodox Church still uses the Julian calendar.)
The Gregorian calendar was accepted in 1582 as being more accurate and it eventually replaced the Julian though it didn’t happen overnight or even worldwide in that year. Astronomers still use the Julian calendar dates for celestial events occurring before the Gregorian calendar was introduced.
The Julian calendar had discrepancies between the calendar dates and the actual time of events like the spring equinox. It was Pope Gregory who decreed that October 4, 1582, on the Julian calendar was to be followed by October 15, 1582, in the new Gregorian calendar. England, with its own church, stuck with the Julian calendar for two more centuries.
The Julian calendar was proposed by Julius Caesar in AUC 708 (46 BC). It was a more accurate version of the existing Roman calendar and it took effect on 1 January AUC 709 (45 BC), by his edict. It was designed with the aid of Greek mathematicians and Greek astronomers for accuracy and was the predominant calendar in the Roman world and most of Europe for more than 1,600 years.
Here’s a post for the penultimate day of 2019. Tomorrow is 2020 and the start of a new decade. Or is it? There is real disagreement on when a new decade begins.
Some people say that the new decade “officially” begins with years ending in 0 while others say a new decade begins in years ending in 1. Is there a correct answer? Generally, people would say that the decade of the 90s began in 1990, 1890 et al.
You can also consider when centuries and millennia begin in the same way. The official answer on that is that the 21st century and the third millennium began on New Year’s Day 2001. That’s because in our modern anno domini time reckoning system there is no year zero. Year 1 BC was followed by year AD 1. But there was certainly much celebration for the new millennium on January 1, 2000.
With decades, it’s more about language than about calendars. Unlike centuries, we would never say “the 200th decade” to mean the next decade. (Technically, the upcoming decade is the 203rd decade. but I am not getting into that.) Chances are we will call this next decade “the twenties” though that might confuse it with the 1920s (the “roaring twenties”).
It will be widely accepted that the new decade will begin when the ball falls at midnight on January 1, 2020, but you can legitimately celebrate again a year later.
If you say to me that something happened in “the 90s” I assume you mean the 1990s and not 1890s. But what do you call that time from 2000-2009? In North America, the term “the aughts” was used (but not by me) and other English speaking countries used “the noughts” or “the noughties.”
And the 2010 -2019 has been referred to as “the teens,” “the teenies,” “the teensies” and “the tens.” I don’t like any of those names. I would probably opt for “the twenty-tens” (“the 2010s”) but my browser’s spell-grammar checker and Grammarly app doesn’t seem to like any of those. Did we go through ten years and we still haven’t decided what to call it? I suppose this decade that is ending will be named in hindsight. Happy 2020, readers!
On this New Year’s Eve, I will look up to the night sky to the brightest star there. That is Sirius, in the constellation Canis Major. You can see it in the evening every year at this time from almost all parts of Earth. Tonight is not only the calendar end of year but, in one of those nice celestial coincidences, it is the midnight culmination of Sirius. That is when it is highest in the sky at midnight, which occurs only once every year.
I need to point out that this midnight is mid-night and not the drop-the-ball midnight we will celebrate tonight. What I will call mid-night is the actual middle of the night, which is midway between sunset and sunrise. For my little piece of Paradelle, that will be at 9:18 pm ET.
If you go to http://aa.usno.navy.mil/data/docs/mrst.php you can get a quick calculation done for your little place on Earth for the times of the rise, set, and transit for the Sun and all major solar system bodies and selected bright stars.
From the Northern Hemisphere, we will look toward the south to see Sirius shining brightly on a clear night. (From the Southern Hemisphere, look overhead or high in the north.)
Sirius, the Dog Star, gets its name from a romanization of the Greek Seirios, meaning “glowing” or “scorching.” It appears almost twice as bright as the next brightest star (Canopus). Sirius appears bright because of its “intrinsic luminosity” and also because of its proximity to Earth. It is 2.6 parsecs away. I know that sounds like Star Trek talk, but the Sirius system is one of Earth’s near neighbours. Sirius is gradually moving closer to the Solar System, so it will slightly increase in brightness over the next 60,000 years. After that time, its distance will begin to increase and it will become fainter. But Sirius doesn’t have to worry about losing its brightest star ranking for 210,000 years.
What we see is a bit of an illusion because “Sirius” is a binary star system, consisting of a white main-sequence star, called Sirius A, and a faint white dwarf companion of called Sirius B. Sirius A is about twice as massive as the Sun and 25 times more luminous than the Sun. Sirius B was actually bigger but consumed its resources and became a red giant. Then, it shed its outer layers and collapsed into its current state as a white dwarf. That happened around 120 million years ago.
All this makes me feel both very tiny, and also part of something so large that I cannot really comprehend it all. So, I will simply go out tonight on this very cold night and look up at Sirius with great wonder.
“The most beautiful thing we can experience is the mysterious. It is the source of all true art and science. He to whom the emotion is a stranger, who can no longer pause to wonder and stand wrapped in awe, is as good as dead —his eyes are closed. The insight into the mystery of life, coupled though it be with fear, has also given rise to religion. To know what is impenetrable to us really exists, manifesting itself as the highest wisdom and the most radiant beauty, which our dull faculties can comprehend only in their most primitive forms—this knowledge, this feeling is at the center of true religiousness.”
― Albert Einstein, Ideas and Opinions