The Andes mountains in South America are a hotspot of astronomy today, but ancient peoples knew it was a great place for astronomy and lived their lives in tune with the night sky. Today we’ll learn all about what they knew, and how they mapped the movements of the stars and planets. Continue reading “Ep. 529: Astronomy of the Andes – Then and Now Pt. 1”
Dr. Emily Holt is an Environmental Archaeologist and Anthropologist who is currently a Visiting Assistant Professor at Miami University of Ohio. Emily’s research focuses on human-environment dynamics in the Nuragic Culture of Bronze Age Sardinia. She directs the Pran’e Siddi Landscape Project (PSLP), an archaeological survey in south-central Sardinia, which is examining the long-term changes in settlement patterns, water use, and the socio-cultural interpretation of natural resources.
Emily is also the president of the non-profit organization Public Scholar Outreach whose mission is to support, produce, promote, and disseminate high-quality public scholarship, especially public scholarship that is peer-reviewed and public scholarship with relevance to contemporary issues. PSO’s primary initiative is to establish Dirt & Words: an online, open access channel of peer-reviewed public scholarship about the human past.
Today, Emily and Fraser will be discussing how ancient cultures understood astronomy, a topic she recently discussed with Paul Sutter on his Space Radio broadcast.
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Astronomy is one of humanity’s oldest obsessions, reaching back all the way to prehistoric times. Long before the Scientific Revolution taught us that the Sun is at the center of the Solar System, or modern astronomy revealed the true extend of our galaxy and the Universe, ancient peoples were looking up at the night sky and finding patterns in the stars.
For some time, scholars believed that an understanding of complex astronomical phenomena (like the precession of the equinoxes) did not predate the ancient Greeks. However, researchers from the Universities of Edinburgh and Kent recently revealed findings that show how ancient cave paintings that date back to 40,000 years ago may in fact be astronomical calendars that monitored the equinoxes and kept track of major events.
Thanks to a decade worth of high-tech imaging, the use of the ancient device called the Antikythera Mechanism can now be confirmed. The device, which was discovered over a century ago in an ancient shipwreck near the Greek island of Antikythera, was used as an astronomical computer.
Archaeologists long suspected that the device was connected to astronomy, but most of the writing on the instrument was indecipherable, which left some question. But a thorough, decade long effort using high-tech scanning methods has revealed much more of the text on the instrument.
The Antikythera Mechanism has about 14,000 characters of text on its mangled, time-weary body. Since its discovery over 100 years ago, very little of that text was readable, only a few hundred characters. It hinted at astronomical use, but detail remained frustratingly out of reach.
Now, the team behind this effort confirms that the mechanism was an astronomical calendar. It showed the position of the planets, the position of the Sun and Moon in the zodiac, the phases of the Moon, and it also predicted eclipses.
According to the team, it was like a teaching tool, or a kind of philosopher’s guide to the galaxy.
The characters were engraved on the front and back sections of the device, and on the inside covers. Some of the writing was very small, only about 1.2 mm (1/20th of an inch) tall. The device itself was about the size of an office box file. It was contained in a wooden box, and was operated with a handle crank.
At the time that it was found, the device was largely an afterthought. The real find at the time was luxury glassware and ceramics, and statues made of bronze and marble found at the shipwreck by sponge divers. But the device attracted attention over the years as different scholars hypothesized what the mechanism was for and how the gears worked.
Professor Mike Edmunds, of Cardiff University, is the Chair of the Antikythera Mechanism Research Project. He said, “This device is just extraordinary, the only thing of its kind. The design is beautiful, the astronomy is exactly right. The way the mechanics are designed just makes your jaw drop. Whoever has done this has done it extremely carefully.”
In fact, a device of this complexity did not appear anywhere for another thousand years.
The device itself is incomplete. The fragments that were found came from a shipwreck discovered in 1901. That ship was a mid-1st century BC ship, a large one for its time at 40 meters (130 ft) long. It’s hoped that additional fragments of the device can be found by architects visiting the original shipwreck. But event though it’s incomplete, most of the inscriptions are there, as are 20 gears that displayed planets.
According to the team responsible for imaging the text on the device, almost all of the text on the device’s 82 fragments has been deciphered. It remains to be seen if any other surviving fragments, if found, will contain more text, and if that text will shed any more light on this remarkable device.
A team from the University of Birmingham recently announced an astronomical discovery in Scotland marking the beginnings of recorded time.
Announced last month in the Journal of Internet Archaeology, the Mesolithic monument consists of a series of pits near Aberdeenshire, Scotland. Estimated to date from 8,000 B.C., this 10,000 year old structure would pre-date calendars discovered in the Fertile Crescent region of the Middle East by over 5,000 years.
Originally unearthed by the National Trust for Scotland in 2004, the site is designated as Warren Field near the town of Crathes. It consists of 12 pits in an arc 54 metres long that seem to correspond with 12 lunar months, plus an added correction to bring the calendar back into sync with the solar year on the date of the winter solstice.
“The evidence suggests that hunter-gatherer societies in Scotland had both the need and sophistication to track time across the years, to correct for seasonal drift of the lunar year” said team leader and professor of Landscape Archaeology at the University of Birmingham Vince Gaffney.
We talked last week about the necessity of timekeeping as cultures moved from a hunter-gatherer to agrarian lifestyle. Such abilities as marking the passage of the lunar cycles or the heliacal rising of the star Sirius gave cultures the edge needed to dominate in their day.
For context, the pyramids on the plains of Giza date from around 2500 B.C., The Ice Man on display in Bolzano Italy dates from 3,300 B.C., and the end of the last Ice Age was around 20,000 to 10,000 years ago, about the time that the calendar was constructed.
“We have been taking photographs of the Scottish landscape for nearly 40 years, recording thousands of archaeological sites that would never have been detected from the ground,” said manager of Aerial projects of the Royal Commission of Aerial Survey Projects Dave Cowley. “It’s remarkable to think that our aerial survey may have helped to find the place where time was invented.”
The site at Warren Field was initially discovered during an aerial survey of the region.
The use of such a complex calendar by an ancient society also came as a revelation to researchers. Emeritus Professor of Archaeoastronomy at the University of Leicester Clive Ruggles notes that the site “represents a combination of several different cycles which can be used to track time symbolically and practically.”
The lunar synodic period, or the span of time that it takes for the Moon to return to the same phase (i.e., New-to-New, Full-to-Full, etc) is approximately 29.5 days. Many cultures used a strictly lunar-based calendar composed of 12 synodic months. The Islamic calendar is an example of this sort of timekeeping still in use today.
However, a 12 month lunar calendar also falls out of sync with our modern Gregorian calendar by 11 days (12 on leap years) per year.
The familiar Gregorian calendar is at the other extreme, a calendar that is strictly solar-based. The Gregorian calendar was introduced in 1582 and is still in use today. This reconciled the 11 minute per year difference between the Julian calendar and the mean solar year, which by the time of Pope Gregory’s reform had already caused the calendar to “drift” by 10 days since the 1st Council of Nicaea 325 AD.
Surprisingly, the calendar discovered at Warren Field may be of a third and more complex variety, a luni-solar calendar. This employs the use of intercalary periods, also known as embolismic months to bring the lunar and solar calendar back into sync.
The modern Jewish calendar is an example of a luni-solar hybrid, which adds an extra month (known as the 2nd Adar or Adar Sheni) every 2-3 years. This will next occur in March 2014.
The Greek astronomer Meton of Athens noted in 5th century B.C. that 235 synodic periods very nearly add up to 19 years, to within a few hours. Today, this period bears his name, and is known as a metonic cycle. The Babylonian astronomers were aware of this as well, and with the discovery at Warren Field, it seems that ancient astronomers in Scotland may have been moving in this direction of advanced understanding as well.
It’s interesting to note that the site at Warren Field also predates Stonehenge, the most famous ancient structure in the United Kingdom by about 6,000 years. 10,000 years ago would have also seen the Earth’s rotational north celestial pole pointed near the +3.9th magnitude star Rukbalgethi Shemali (Tau Herculis) in the modern day constellation of Hercules. This is due to the 26,000 year wobble of our planet’s axis known as the precession of the equinoxes.
The Full Moon nearest the winter solstice also marks the “Long Nights Moon,” when the Full Moon occupies a space where the Sun resides during the summer months and rides high above the horizon for northern observers all night. The ancients knew of the five degree tilt that our Moon has in relation to the ecliptic and how it can ride exceptionally high in the sky every 18.6 years. We’re currently headed towards a ‘shallow year’ in 2015, where the Moon rides low in relation to the ecliptic. From there, the Moon’s path in the sky will get progressively higher each year, peaking again in 2024.
Who built the Warren Field ruins along the scenic Dee Valley of Scotland? What other surprises are in store as researchers excavate the site? One thing is for certain: the ancients were astute students of the sky. It’s fascinating to realize how much of our own history has yet to be told!
Is this 2-meter-high slab of lichen-covered rock in a UK park an astronomical marker used by Neolithic people? Researchers from Nottingham Trent University are suggesting that may in fact be the case, based on the stone’s alignment, angle and proximity to other significant Stone and Bronze Age sites nearby.
The angular rock, known as the Gardom’s Edge Monolith, resides within the Peak District National Park in the central northern area of England. The research team has found that it’s aligned in such a way that its north side slopes at an angle equal to the maximum altitude of the Sun during the summer solstice.
Not thought to be so much a sundial as a seasonal dial, the shadows cast by the monolith seem to mark specific times of year… possibly denoting the “life cycle” of the Sun in the heavens.
Standing stones being rare in the region, It’s estimated that the monolith was set in place anywhere from 2,500 — 1,500 B.C. Evidence of packed stones and earth at the base also suggests human placement.
The team believes that the stone may have been a gathering point for ancient communities in the area.
“The stone would have been an ideal marker for a social arena for seasonal gatherings,” said Dr. Daniel Brown, lead author of the team’s paper. “It’s not a sundial in the sense that people would have used it to determine an exact time. We think that it was set in position to give a symbolic meaning to its location, a bit like the way that some religious buildings are aligned in a specific direction for symbolic reasons.”
Computer modeling of the stone and the Sun’s position throughout the year show that the stone’s slanted side would be in shadow during the winter, while during the summer it would be lit in the morning and afternoon. During midsummer, however, it would be illuminated all day.
More modeling and photographic work will be needed to confirm this hypothesis. If supported, it could lead to more archaeological study of the area.