Eratosthenes 2021 ADVENT CALENDAR

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• While December is a month of extremes – cold and dark in the northern hemisphere and opposite in the southern – it’s also one of the best months of the year for amateur astronomers and stargazers.December is best known for two meteor showers – the highly active Geminids mid-month and the lesser but still impressive Ursids in late December
• BUT, the first meteor shower of the month is actually on the night of December 2nd. On this night, the Phoenicid Meteor Shower peaks with only a small number of meteors per hour. In December, there are also good opportunities to spot solar system neighbors, watch the celestial dance of our Sun and Moon, and of course make measurements during the solar noon. Be aware and mark the astronomical calendar with the December solstice -a BIG event for our project-!.
• Whatever drives you out to enjoy the sky this month, be sure to bundle up. Being partners in Eratosthenes, we are lucky to be outside during solar noon instead of the astronomers that have to be outside during the night when it is for sure more chilly than during the day, even in the southern hemisphere

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Tuesday, December 7 - Moon Meets Saturn (early evening)The moon's monthly visit with the bright gas giant planets Saturn and Jupiter will kick off after dusk in the southern sky on Tuesday, December 7. Before the sky has fully darkened, try using binoculars (green circle) to find the yellowish dot of Saturn positioned a palm's width to the upper left (or 6 degrees to the celestial northeast) of the waxing crescent moon. Or wait until Saturn is visible with your unaided eyes. Much brighter and whiter Jupiter will be shining off to their upper left. Even brighter Venus will gleam to their lower right.

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They fill my soul with Beauty (which is Hope,)And are far up in Heaven – the stars I kneel toIn the sad, silent watches of my night;While even in the meridian glare of dayI see them still – two sweetly scintillantVenuses, unextinguished by the sun!”― Edgar Allan Poe, The Raven and Other Poems

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“A philosopher once asked, “Are we human because we gaze at the stars, or do we gaze at them because we are human?” Pointless, really…”Do the stars gaze back?” Now, that’s a question.”― Neil Gaiman, Stardust Animals under a night sky from Antoine Vérard’s ‘L’Art de bien vivre et de bien mourir’ (The Art of Living Well and of Dying Well) , 1494

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The peak of the Geminid Meteor Shower If you haven’t seen any of the meteor showers so far month, December 13th-14th is the night for it! On this night, the Geminid meteor shower will peak with up to 120 meteors per hour – it’s a great show! The Geminids are considered to be one of the most spectacular meteor showers of the year. The shower owes its name to the constellation Gemini because the meteors seem to emerge from this constellation in the sky. Unlike most other meteor showers, the Geminids are not associated with a comet but with an asteroid: the 3200 Phaethon. The asteroid takes about 1.4 years to orbit the Sun. link

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Famous Birthdays on December 14th (related to time and space) 1503 Nostradamus [Michel de Nostre-Dam], French astrologist and prophet (Les Propheties), born in Saint-Rémy-de-Provence, France (death: 1566) Nostradamus studied medicine and became a physician, treating plague victims throughout France and Italy. It’s believed he had a psychic awakening. He began to practice the occult and make predictions of the future, which he published in The Prophecies. Many people today believe his predictions have come true or will in the future. 1546 Tycho Brahe, Danish astronomer (Golden nose), born in Knudstrup, Denmark (died in 1601 in Prague) Danish astronomer whose work in developing astronomical instruments and in measuring and fixing the positions of stars paved the way for future discoveries. His observations—the most accurate possible before the invention of the telescope—included a comprehensive study of the solar system and accurate positions of more than 777 fixed stars

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Saturnalia, held in mid-December, is an ancient Roman pagan festival honoring the agricultural god Saturn. Saturnalia celebrations are the source of many of the traditions we now associate with Christmas. Saturnalia, the most popular holiday on the ancient Roman calendar, derived from older farming-related rituals of midwinter and the winter solstice, especially the practice of offering gifts or sacrifices to the gods during the winter sowing season. The pagan celebration of Saturn, the Roman god of agriculture and time, began as a single day, but by the late Republic (133-31 B.C.) it had expanded to a weeklong festival beginning December 17. (On the Julian calendar, which the Romans used at the time, the winter solstice fell on December 25.) How the Romans Celebrated Saturnalia During Saturnalia, work and business came to a halt. Schools and courts of law closed, and the normal social patterns were suspended. People decorated their homes with wreaths and other greenery, and shed their traditional togas in favor of colorful clothes known as synthesis. Even slaves did not have to work during Saturnalia, but were allowed to participate in the festivities; in some cases, they sat at the head of the table while their masters served them. Instead of working, Romans spent Saturnalia gambling, singing, playing music, feasting, socializing and giving each other gifts. Wax taper candles called cerei were common gifts during Saturnalia, to signify light returning after the solstice. On the last day of Saturnalia celebrations, known as the Sigillaria, many Romans gave their friends and loved ones small terracotta figurines known as signillaria, which may have referred back to older celebrations involving human sacrifice. Saturnalia was by far the jolliest Roman holiday; the Roman poet Catullus famously described it as “the best of times.” So riotous were the festivities that the Roman author Pliny reportedly built a soundproof room so that he could work during the raucous celebrationsTemple of Saturn and Other Saturnalia Customs Constructed in the fourth century A.D. to replace an earlier temple, the Temple of Saturn in Rome served as the ceremonial center of later Saturnalia celebrations. On the first day of the festivities, a young pig would often be publicly sacrificed at the temple, which was located in the northwest corner of the Roman Forum. The cult statue of Saturn in the temple traditionally had woolen bonds tied around his feet, but during Saturnalia these bonds were loosened to symbolize the god’s liberation. In many Roman households, a mock king was chosen: the Saturnalicius princeps, or “leader of Saturnalia,” sometimes also called the “Lord of Misrule.” Usually a lowlier member of the household, this figure was responsible for making mischief during the celebrations—insulting guests, wearing crazy clothing, chasing women and girls, etc. The idea was that he ruled over chaos, rather than the normal Roman order. The common holiday custom of hiding coins or other small objects in cakes is one of many dating back to Saturnalia, as this was a method of choosing the mock king. How Saturnalia Led to Christmas Thanks to the Roman Empire’s conquests in Britain and the rest of Europe from the second century B.C. to the fourth century A.D.—and their suppression of older seasonal rites practiced by the Celts and other groups—today’s Western cultures derive many of their traditional celebrations of midwinter from Saturnalia. The Christian holiday of Christmas, especially, owes many of its traditions to the ancient Roman festival, including the time of year Christmas is celebrated. The Bible does not give a date for Jesus’ birth; in fact, some theologians have concluded he was probably born in spring, as suggested by references to shepherds and sheep in the Nativity story. But by the fourth century A.D., Western Christian churches settled on celebrating Christmas on December 25, which allowed them to incorporate the holiday with Saturnalia and other popular pagan midwinter traditions.

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Getting ready for December Solstice? Your Eratosthenes measurements are valid starting from today, the angle will not have a "measureable" change What is December Solstice? There are two solstices every year: one in December and one in June. The December solstice marks the shortest day north of the equator and the longest day in the south. The December solstice is the moment the Sun is directly above the Tropic of Capricorn in the Southern Hemisphere. This is the southernmost latitude it reaches during the year. After the solstice, it begins moving north again. Since the Northern Hemisphere is tilted away from the Sun in December, it receives less sunlight during the course of a day. At the solstice, the North Pole's tilt away from the Sun is greatest, so this event marks the shortest day of the year north of the equator. This effect is greatest in locations that are farther away from the equator. In tropical areas, the shortest day is just a little shorter than 12 hours; in the temperate zone, it is significantly shorter; and places within the Arctic Circle experience polar night, when the Sun does not rise at all. Longest Day in the South Conversely, the day of the December solstice is the longest day of the year in the Southern Hemisphere. Here, too, the effect is greater the farther a location is away from the equator. Places within the Antarctic Circle experience Midnight Sun, when the Sun does not set at night. Solstice and seasons The December solstice marks the start of winter in the Northern Hemisphere and the start of summer in the Southern Hemisphere, according to one definition. The shortest day of the year is commonly associated with the latest sunrise and earliest sunset of the year. However, in most locations, the earliest sunset happens a few days before the solstice, while the latest sunrise occurs some days after it Why the date varies? The date of the equinoxes and solstices varies because a year in our calendar does not exactly match the length of the tropical year—the time it takes the Earth to complete an orbit around the Sun. Today's Gregorian calendar has 365 days in a common year and 366 days in a leap year. However, our planet takes about 365.242199 days to orbit the Sun. This means that the timing of the equinoxes and solstices slowly drifts apart from the Gregorian calendar, and the solstice happens about 6 hours later each year. Eventually, the accumulated lag becomes so large that it falls on the following date. To realign the calendar with the tropical year, a leap day is introduced (nearly) every four years. When this happens, the equinox and solstice dates shift back to the earlier date again. Other factors influencing the timing of the equinoxes and solstices include variations in the length of a tropical year and in the orbital and daily rotational motion of the Earth, such as the “wobble” in the Earth's axis (precession).

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The winter solstice, the longest night of the year, falls on December 21 or 22 in the Northern Hemisphere and June 20 or 21 in the Southern. Since ancient times, people all over the world have recognized this important astronomical occurrence and celebrated the subsequent “return” of the Sun in a variety of different ways. Old solstice traditions have influenced holidays we celebrate now, such as Christmas and Hanukkah. Here are some solstice traditions both new and old to help light your way to longer days.

• Soyal is the winter solstice celebration of the Hopi Indians of northern Arizona. Ceremonies and rituals include purification, dancing, and sometimes gift-giving. At the time of the solstice, Hopi welcome the kachinas, protective spirits from the mountains. Prayer sticks are crafted and used for various blessings and other rituals.

Image: Brooklyn Museum, New York, Museum Expedition 1903, Museum Collection Fund (03.325.4653)

• The Persian festival Yalda, or Shab-e Yalda is a celebration of the winter solstice in Iran that started in ancient times. It marks the last day of the Persian month of Azar. Yalda is viewed traditionally as the victory of light over dark, and the birthday of the sun god Mithra. Families celebrate together with special foods like nuts and pomegranates and some stay awake all night long to welcome the morning sun.

Mithra (Image: © Photos.com/Jupiterimages )

• Inti Raymi: This solstice celebration comes in June rather than December. But for Peru it is a winter solstice, and this Incan celebration is in honor of the Sun god. Originally celebrated by the Inca before the arrival of Spanish conquistadors, the festivities included feasts and sacrifices, of animals or possibly even children. The Spaniards banned the holiday, but it was revived (with mock sacrifices instead of real ones) in the 20th century and is still celebrated today.

• The ancient Roman festival of Saturnalia is perhaps the most closely linked with the modern celebration of Christmas. This festival happened around the time of the winter solstice and celebrated the end of the planting season. There were games and feasts and gift-giving for several days, and social order was inverted—slaves did not work and were briefly treated as equals.

The Temple of Saturn, among the ruins of the Roman Forum, Rome (Image: © Stefano Pellicciari/stock.adobe.com)

• Even Antarctica gets its share of solstice celebration, thanks to the researchers staying there over the long, dangerously cold season. While those of us in the Northern Hemisphere are enjoying the most daylight hours, in the Southern Hemisphere they are celebrating Midwinter. Festivities include special meals, films, and sometimes even handmade gifts.

Palmer Station, Antarctica Image Christopher Michel

• St. Lucia’s Day is a festival of lights celebrated in Scandinavia around the time of the winter solstice. Although it is now meant to honor St. Lucia, a Christian martyr, it has been incorporated with earlier Norse solstice traditions, such as lighting fires to ward off spirits during the longest night. Girls dress up in white gowns with red sashes and wear wreaths of candles on their heads in honor of St. Lucia

A statue of St. Lucy on display during a Santa Lucia celebration in Syracuse, Italy.( Image© valentina5000/Fotolia)

• Dong Zhi, the “arrival of winter,” is an important festival in China. It is a time for family to get together and celebrate the year they have had. Based on the traditional Chinese celestial calendar, the holiday generally falls between the 21st and 23rd of December. It is thought to have started as an end-of-harvest festival, with workers returning from the fields and enjoying the fruits of their labors with family. Special foods, such as tang yuan (glutinous rice balls), are enjoyed

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Sometimes everythinghas to beinscribed acrossthe heavens so you can findthe one linealready writteninside you.– David Whyte, The Journey I am tired, I am wearyI could sleep for a thousand yearsA thousand dreams that would awake meDifferent colors made of tears– Velvet Underground, Venus In Chains From the Augsburger Wunderzeichenbuch (The Book of Miracles) – ca. 1552

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Advent Calendar

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not yet, the time for this door!

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Ô nuit Viens apporter à la terre Le calme enchantement de ton mystère L'ombre qui t'escorte est si douce Si doux est le concert de tes voix chantant l'espérance Si grand est ton pouvoir transformant tout en rêve heureux Ô nuit Ô laisse encore à la terre Le calme enchantement de ton mystère L'ombre qui t'escorte est si douce Est-il une beauté aussi belle que le rêve Est-il de vérité plus douce que l'espérance

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The Sun is the star at the center of our solar system. It is an almost perfect sphere of super-hot gases whose gravity holds the solar system together. The energy produced by the Sun is essential for life on Earth and is a driving force behind the Earth’s weather. Facts about the Sun

• The Sun is all the colours mixed together, this appears white to our eyes.
• The Sun is composed of hydrogen (70%) and Helium (28%).
• The Sun is a main-sequence G2V star (or Yellow Dwarf).
• The Sun is 109 times wider than the Earth and 330,000 times as massive.
• The Sun’s surface area is 11,990 times that of the Earth’s.
• The distance between the Earth and the Sun is an Astronomical Unit (AU)
• One million Earths could fit inside the Sun.A hollow Sun would fit around 960,000 spherical Earths. If squished inside with no wasted space, then around 1,300,000 would fit inside. The Sun’s surface area is 11,990 times that of the Earth’s.
• The Sun contains 99.86% of the mass in the Solar System.The mass of the Sun is approximately 330,000 times greater than that of Earth. It is almost three quarters Hydrogen, whilst most of the remaining mass is Helium.
• The Sun is an almost perfect sphere.There is a 10-kilometre difference between the Sun’s polar and equatorial diameter. This means it is the closest thing to a perfect sphere that has been observed in nature.
• The Sun will consume the Earth.When the Sun has burned all its Hydrogen, it will continue to burn helium for 130 million more years. During this time, it will expand to the point that it will engulf Mercury, Venus, and the Earth. At this stage it will have become a red giant
• The Sun will one day be about the size of Earth.After its red giant phase, the Sun will collapse. It will keep its enormous mass with the approximate volume of our planet. When this happens, it will have become a white dwarf.
• The temperature inside the Sun can reach 15 million degrees Celsius.Energy is generated at the Sun’s core, by nuclear fusion, as Hydrogen converts to Helium. Hot objects expand, the Sun would explode if it were not for its enormous gravitational force. The temperature on the surface of the Sun is closer to 5,600 degrees Celsius.
• Light from the Sun takes eight minutes to reach Earth. The Sun is an average distance of 150 million kilometres from the Earth. Light travels at 300,000 kilometres per second. Dividing one by the other gives us an approximate time of 500 seconds (or eight minutes and 20 seconds). Although this energy reaches Earth in a few minutes, it will already have taken millions of years to travel from the Sun’s core to its surface.
• The Sun travels at 220 kilometres per second.The Sun is 24,000-26,000 light years from the galactic centre. It takes the Sun 225-250 million years to complete an orbit of the centre of the Milky Way.
• The distance from the Sun to Earth changes throughout the year.This is because the Earth travels on an elliptical orbit around the Sun. The distance between the two bodies varies from 147 to 152 million kilometres.
• The Sun is middle-aged.At around 4.6 billion years old, the Sun has already burned off about half of its store of Hydrogen. It has enough left to continue to burn Hydrogen for approximately 5 billion years. The Sun is currently a type of star known as a Yellow Dwarf.
• The Sun has a very strong magnetic field.Magnetic energy released by the Sun during magnetic storms causes solar flares. We see these as sunspots. In sunspots, the magnetic lines twist and they spin, much like a tornado would on Earth.
• The Sun generates solar wind.The wind is a stream of charged particles. This travels at approximately 450 kilometres per second through the solar system. Solar wind occurs when the magnetic field of the Sun extends into space.
• Sol is the Latin for SunThis is where the word “solar” comes from, which is used to describe things that are derived from, related to, or caused by the Sun

Sources: https://solarsystem.nasa.gov/solar-system/sun/overview/ https://www.nasa.gov/sun

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You don't have a telescope? Maybe, writing to Santa? (if you were a good kid....) Meanwhile, you can use this online tool (© Dominic Ford ) Click on the photo and check the possible options (I see that if i get up early in the morning, a bit before sunrise, i can see Mars on my sky, What about you?)

Happy Holidays Season, dear friends!