11.6 Astronomy and geography

Ancient Mediterranean civilizations made significant strides in astronomy and geography. They observed celestial bodies, developed mathematical models, and created detailed maps of the known world. These advancements shaped their understanding of the universe and their place within it.

The intersection of astronomy and geography led to crucial developments in navigation, timekeeping, and agriculture. Ancient scholars calculated Earth's size, created star catalogs, and established coordinate systems, laying the groundwork for future scientific discoveries and exploration.

Astronomy in ancient Mediterranean

• Ancient civilizations in the Mediterranean region, such as the Babylonians, Egyptians, and Greeks, made significant contributions to the field of astronomy through their celestial observations and mathematical calculations
• Astronomy played a crucial role in the development of mythology, religion, and timekeeping in ancient Mediterranean societies, with celestial bodies and phenomena often associated with deities and used to mark important dates and seasons

Celestial observations by ancient civilizations

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• Ancient Egyptians developed a solar calendar based on the heliacal rising of the star Sirius (Sothis), which coincided with the annual flooding of the Nile
• Babylonians recorded detailed observations of celestial phenomena, such as the positions of planets, eclipses, and the appearance of comets
• Greeks made systematic observations of the night sky, recognizing patterns and cycles in the motion of celestial bodies (constellations, planetary retrograde motion)

Astronomical knowledge of Babylonians

• Babylonians developed a sophisticated mathematical approach to astronomy, using a sexagesimal (base-60) number system
• They created detailed ephemerides, which were tables predicting the positions of celestial bodies at regular intervals
• Babylonians recognized the 18.6-year cycle of lunar eclipses, known as the Saros cycle
• They also developed a zodiac system, dividing the celestial equator into 12 equal parts (signs) based on the constellations

Greek contributions to astronomy

• Greek astronomers, such as Aristarchus of Samos and Eratosthenes, proposed heliocentric models of the solar system, although these ideas were not widely accepted at the time
• Hipparchus created the first comprehensive star catalog, estimating the positions and brightness of around 850 stars
• He also discovered the precession of the equinoxes, the gradual shift in the orientation of Earth's rotational axis
• Greek astronomers developed geometric models to explain the apparent motion of celestial bodies (epicycles, deferents)

Ptolemaic vs Copernican models

• The Ptolemaic model, proposed by Claudius Ptolemy in the 2nd century CE, was a geocentric system that placed Earth at the center of the universe, with the Sun, Moon, planets, and stars revolving around it
• The Copernican model, introduced by Nicolaus Copernicus in the 16th century CE, was a heliocentric system that placed the Sun at the center of the solar system, with Earth and other planets revolving around it
• The Copernican model, although more accurate than the Ptolemaic model, faced resistance from the Church and was not widely accepted until the 17th century

Influence of astronomy on mythology

• Many ancient Mediterranean cultures associated celestial bodies and phenomena with deities and mythological figures (Sun god Ra in Egyptian mythology, Apollo as the sun god in Greek mythology)
• Constellations were often linked to mythological stories and used for storytelling and cultural transmission
• The Milky Way was sometimes seen as a heavenly river or a path to the afterlife
• Eclipses and comets were often interpreted as omens or signs from the gods, influencing political and religious decisions

Geography of ancient Mediterranean

• The geography of the Mediterranean region played a significant role in shaping the development of ancient civilizations, influencing their settlement patterns, trade routes, and cultural exchange
• The Mediterranean Sea served as a vital transportation and communication link between the various civilizations that flourished along its shores, facilitating the spread of ideas, technologies, and goods

Physical geography of Mediterranean region

• The Mediterranean region is characterized by a combination of mountainous terrain, coastal plains, and islands
• The region is located at the intersection of three continents: Europe, Africa, and Asia
• The Mediterranean Sea is a semi-enclosed sea connected to the Atlantic Ocean through the Strait of Gibraltar
• The sea is divided into the Western and Eastern basins, with the Italian Peninsula and the island of Sicily acting as a natural boundary

Climate and environmental factors

• The Mediterranean region experiences a distinctive climate, known as the Mediterranean climate, characterized by hot, dry summers and mild, wet winters
• This climate is influenced by the region's latitude, topography, and proximity to the sea
• The Mediterranean climate is suitable for the cultivation of crops such as olives, grapes, and wheat, which formed the basis of ancient Mediterranean agriculture
• The region's vegetation is characterized by evergreen trees and shrubs, such as oak, pine, and maquis (a type of shrubland)

Major landforms and bodies of water

• The Mediterranean region is home to several major mountain ranges, such as the Alps, Apennines, and Taurus Mountains
• Significant peninsulas in the region include the Iberian, Italian, and Balkan peninsulas
• The region is dotted with numerous islands, such as Crete, Cyprus, Sicily, Sardinia, and the Balearic Islands
• Major rivers that drain into the Mediterranean Sea include the Nile, Ebro, Rhone, and Po

Geographic advantages for civilization development

• The Mediterranean climate and fertile soils along river valleys and coastal plains supported the development of agriculture and the growth of settlements
• The Mediterranean Sea provided a means of transportation and communication, enabling trade, cultural exchange, and the spread of ideas and technologies
• The presence of natural harbors and sheltered bays along the coastline facilitated the development of maritime trade and the establishment of port cities (Tyre, Carthage, Piraeus)
• The mountainous terrain provided natural defenses and encouraged the development of independent city-states and regional powers

Cartography in ancient world

• Cartography, the art and science of mapmaking, has its roots in the ancient world, with the earliest known maps dating back to ancient Babylonia and Egypt
• Ancient Mediterranean civilizations made significant contributions to the development of cartography, with Greek and Roman geographers and astronomers creating increasingly accurate and detailed maps of the known world

Early mapmaking techniques

• The earliest maps were often simple representations of local areas, such as town plans or regional maps, carved on clay tablets or painted on walls
• The Babylonians created maps of cities and regions on clay tablets, using a system of symbols and labels to represent features such as rivers, mountains, and settlements
• The ancient Egyptians produced maps of the Nile Valley and the surrounding desert regions, using surveying techniques and astronomical observations to determine the orientation and scale of their maps

Contributions of Greek geographers

• Greek geographers, such as Anaximander and Hecataeus of Miletus, created the first world maps, representing the known world as a circular landmass surrounded by the ocean
• Eratosthenes, a Greek geographer and astronomer, made significant contributions to cartography by calculating the circumference of the Earth and creating a grid system of parallels and meridians
• Strabo, another notable Greek geographer, wrote the 17-volume work "Geographica," which included detailed descriptions of the known world and discussed the importance of geography in understanding human activities and historical events

Ptolemy's Geographia

• Claudius Ptolemy, a Greek-Egyptian geographer and astronomer, wrote the influential work "Geographia" in the 2nd century CE
• Ptolemy's "Geographia" included a detailed description of the known world, along with instructions on how to create maps using a grid system of latitude and longitude
• He introduced the concept of map projection, using a conic projection to represent the curved surface of the Earth on a flat map
• Ptolemy's work served as a basis for mapmaking for centuries, influencing Islamic and European cartographers

Roman itineraria and periploi

• The Romans produced itineraria, which were lists of destinations and distances along Roman roads, used for military, administrative, and trade purposes
• The Tabula Peutingeriana is a notable example of a Roman itinerarium, showing the road network of the Roman Empire and the distances between cities and landmarks
• Periploi were ancient navigational guides that provided detailed descriptions of coastlines, harbors, and sailing routes, used by Greek and Roman mariners
• The "Periplus of the Erythraean Sea," written by an unknown Greek author in the 1st century CE, is a notable example of a periplus, describing the maritime trade routes between the Red Sea and the Indian Ocean

Influence of geography on trade routes

• The geography of the Mediterranean region, with its numerous islands, peninsulas, and coastal plains, influenced the development of maritime trade routes
• The Phoenicians, Greeks, and Romans established extensive trade networks across the Mediterranean, connecting Europe, North Africa, and the Near East
• The Silk Road, a network of overland trade routes connecting the Mediterranean world with East Asia, was influenced by the geography of the regions it traversed, following mountain passes, desert oases, and river valleys
• The monsoon winds in the Indian Ocean facilitated the development of maritime trade routes between the Red Sea, the Persian Gulf, and the Indian subcontinent

Navigation and exploration

• Navigation and exploration played a crucial role in the development of trade, cultural exchange, and the expansion of knowledge in the ancient Mediterranean world
• Advances in navigation techniques and maritime technology enabled ancient Mediterranean civilizations to undertake increasingly long-distance voyages and explore new regions

Celestial navigation techniques

• Ancient mariners used celestial navigation techniques, observing the positions of the sun, stars, and planets to determine their location and direction at sea
• The Phoenicians and Greeks used the Pole Star (Polaris) to navigate in the northern hemisphere, as it remains nearly stationary in the night sky
• The Greeks developed the concept of latitude, using the altitude of the sun at noon or the position of certain stars to determine their north-south position
• The use of the gnomon, a simple sundial, allowed mariners to determine the time of day and the latitude based on the length and direction of the shadow cast by the sun

Advancements in maritime technology

• The development of the sail, which harnessed wind power, revolutionized maritime transportation in the ancient Mediterranean
• The Phoenicians and Greeks developed advanced shipbuilding techniques, constructing larger and more seaworthy vessels (biremes, triremes) capable of long-distance voyages
• The invention of the anchor and improvements in hull design increased the stability and safety of ships
• The use of the sounding weight, a lead weight attached to a rope, allowed mariners to measure water depth and detect underwater hazards

Phoenician and Greek exploration

• The Phoenicians, renowned as skilled mariners and traders, established colonies and trading posts throughout the Mediterranean, reaching as far as the Atlantic coasts of Spain and Morocco
• The Phoenician explorer Hanno the Navigator is believed to have undertaken a voyage along the western coast of Africa in the 5th century BCE, reaching as far as present-day Senegal or Cameroon
• Greek explorers and colonists expanded throughout the Mediterranean and Black Sea regions, establishing settlements in southern Italy, Sicily, North Africa, and the eastern Mediterranean
• The Greek historian Herodotus, known as the "Father of History," wrote extensive accounts of the lands and peoples encountered during his travels in the Mediterranean and beyond

Pytheas' voyage to British Isles

• Pytheas, a Greek explorer and geographer from Massalia (modern-day Marseille), undertook a voyage to the British Isles and beyond in the 4th century BCE
• He sailed along the Atlantic coast of Europe, reaching as far north as the Arctic Circle, and provided the first written accounts of the British Isles and the phenomena of the midnight sun and polar ice
• Pytheas' voyage demonstrated the extent of Greek exploration and the expanding horizons of the ancient Mediterranean world

Nearchus' voyage in Indian Ocean

• Nearchus, a Greek admiral serving under Alexander the Great, led a fleet from the Indus River in present-day Pakistan to the Persian Gulf in 325-324 BCE
• His voyage, known as the "Indica," explored the coast of the Indian Ocean and provided valuable information about the region's geography, peoples, and resources
• Nearchus' account of his voyage, preserved in the works of later historians (Arrian, Strabo), contributed to the knowledge of the Indian Ocean and the lands beyond the eastern limits of the Mediterranean world

Intersection of astronomy and geography

• Astronomy and geography were closely intertwined in the ancient Mediterranean world, with astronomical observations and calculations playing a crucial role in the development of cartography, navigation, and the understanding of the Earth's shape and size
• The intersection of these two disciplines led to significant advancements in the understanding of the world and the place of human civilization within it

Astronomical basis for latitude and longitude

• Ancient Greek astronomers and geographers recognized the importance of astronomical observations in determining latitude and longitude
• The concept of latitude was based on the observation that the altitude of the celestial pole (and thus the Pole Star) above the horizon changes as one moves north or south
• The concept of longitude was more challenging, as it required accurate timekeeping and the ability to determine the difference in local time between two locations
• Hipparchus, a Greek astronomer, proposed a system of latitude and longitude based on celestial observations, although the accurate determination of longitude remained elusive until the invention of precise marine chronometers in the 18th century

Eratosthenes' calculation of Earth's circumference

• Eratosthenes, a Greek geographer and astronomer, made a remarkable calculation of the Earth's circumference in the 3rd century BCE
• He observed that on the summer solstice, the sun was directly overhead at noon in Syene (modern-day Aswan), while in Alexandria, it cast a shadow corresponding to an angle of about 7.2 degrees
• By measuring the distance between Syene and Alexandria and using basic geometry, Eratosthenes estimated the Earth's circumference to be around 252,000 stadia (approximately 46,000 km or 28,500 miles)
• Eratosthenes' calculation, although not exact, was a significant achievement in understanding the size of the Earth and laid the foundation for later advancements in geography and cartography

Hipparchus' star catalog and coordinate system

• Hipparchus, a Greek astronomer, created the first comprehensive star catalog in the 2nd century BCE, estimating the positions and brightness of around 850 stars
• He developed a coordinate system for mapping the positions of stars, using the celestial equator and the ecliptic (the path of the sun) as reference planes
• Hipparchus' star catalog and coordinate system laid the foundation for the later work of Ptolemy and the development of celestial cartography
• His work also contributed to the understanding of the precession of the equinoxes, the gradual shift in the orientation of Earth's rotational axis

Astronomical alignments in ancient architecture

• Many ancient Mediterranean structures, such as temples and monuments, were designed with astronomical alignments in mind
• The Great Pyramid of Giza, for example, is precisely aligned with the cardinal directions, with its faces oriented to the north, south, east, and west
• The Parthenon in Athens is oriented to align with the rising of the Pleiades constellation on the day of the Panathenaic festival
• The Mnajdra temples in Malta are aligned with the equinoxes and solstices, with sunlight illuminating specific chambers on these dates
• These astronomical alignments demonstrate the importance of astronomy in ancient Mediterranean religion, culture, and architecture

Influence of astronomy on agriculture and calendars

• Astronomical observations played a crucial role in the development of agricultural practices and calendars in the ancient Mediterranean world
• The rising of certain stars (Sirius in ancient Egypt) or the position of the sun at the solstices and equinoxes were used to mark the beginning of agricultural seasons and guide farming activities
• Ancient Egyptians developed a solar calendar based on the heliacal rising of Sirius, which coincided with the annual flooding of the Nile, a critical event for agriculture
• The Babylonians developed a lunisolar calendar, which combined the cycles of the moon and the sun to create a 19-year cycle (the Metonic cycle) that kept the calendar in sync with the seasons
• The Roman calendar, which forms the basis of the modern Gregorian calendar, was originally a lunar calendar but was later reformed by Julius Caesar in 45 BCE to follow a solar year of 365.25 days (the Julian calendar)
• The influence of astronomy on agriculture and calendars demonstrates the practical applications of astronomical knowledge in the daily lives of ancient Mediterranean civilizations