Alexandre Cherman is a member of The Planetary Society and writes in our Blog Section.
Born in Rio, he has a B.S. in Astronomy, and a Master’s and a Doctor’s degree in Physics. He works at the Rio de Janeiro Planetarium as Head of Astronomy, where he oversees show production, exhibits and the general scientific content produced by a staff of twelve resident astronomers. He specialized in Fundamental Astronomy, Chronology and Cosmology. He has six published books. For six years he was the Scientific Director of the Association of Brazilian Planetariums, and later became its President. Since 2007, he is the Brazilian representative at the International Planetarium Society Council. In 2012, he was awarded an IPS Fellowship.
Let me propose a mental exercise: imagine that we do not number our years and the only way to tell them apart is through the matching of the day of the week with the day of the month...
In the Julian Calendar, the year has 365 days and the week, 7. 365 days is not a multiple of 7! That is what we call immeasurability.
The incomensurability of the week and the month causes some confusion. We never know in far advance which day of the month belongs to which day of the week.
Easter is the great Christian celebration. If Christmas represents the birth of Jesus Christ, Easter symbolizes His resurrection. And, honestly, which should be bigger?
Every year, when this day comes, I feel compelled to write about it, explaining why April first is known as Fool’s Day.
The year reflects the duration of time Earth takes to complete its path around the Sun. This time period, unfortunately, can not be expressed, in days, using an with an integer number.
I just saw a video posted on Weather Channel´s Facebook page where a 'specialist' explains that during the equinox, Earth’s axis will be perpendicular to the Sun! No, it won’t.
As Pontifex Maximus, Caesar was already contemplating on reforming the calendar. He just didn’t know how...
The Roman Calendar was completely out of sync with the seasons and one of the many things Julius Cesar decided to do when he seized the command of Rome was to fix the calendar.
In december, the sun reaches its maximum southern distance to the Celestial Equator. This is “the proof that the Sun is invincible, and that it will turn around and win the fight against darkness”. Know more...
Last we talked about our calendar and how Rome’s second king has just created to extra months to cover the winter. He was apparently happy with that. But meanwhile, in Egypt…
As much as I like the attention and all the happy thoughts, I do fell obligated to tell you that this day is far less encompassing than my friends think.
For over 600 hundred years of Roman history, probably none of them treated the calendar well. And the key word to this is a mouthful: incommensurability.
Isn’t it obvious that the last day of the weekend (emphasis on the 'end' part of weekend) is the last day of the week? Not so fast!
Last we met, we talked about the first King of Rome and his new calendar. After his death was addressed a new calendar, and ended the Winter nonsense. They did that by creating two extra months...
This calendar had a period that was unaccounted for the Winter. And It was very unusual to us. One year ended and people had to wait two months until the new year begun!
The Indian calendar is a solar calendar very similar to our own Gregorian calendar. But this calendar is not for beginners...
Let’s talk about this rich Hindu tradition and how it relates to astronomy.
My approach here is strictly semantical and astronomical. You are free not to like this new time zone. But please, don’t say it is wrong…
Astronomy could have been one of the most powerful pushes in the creation of modern civilization. When farmers finally understood that they could “read” the seasons in the stars, they leaped into an age of optimized crops, allowing people to form the first cities.