History-of-Astronomy

The History of Astronomy

Ancient Civilizations

• Early astronomers: Babylonians, Egyptians, Greeks.

• Celestial tracking for agriculture and navigation.

• Egyptian pyramids aligned with stars; Babylonians created early star catalogs.

Early Observations

• Babylonian astronomy began around 1900 BCE.

• Careful records of celestial phenomena: Sun, Moon, planets, stars, and seasonal changes.

Lunar Calendar

• Babylonians used a lunar calendar for agriculture and rituals.

• Year divided into 12 lunar months starting with the new moon's crescent sighting.

Zodiac and Constellations

• Developed the zodiac: 12 equal parts of the sky corresponding to constellations.

• Influenced cultures including Greece and provided basis for modern astrology.

Mathematical Astronomy

• Skilled in mathematics using a sexagesimal (base-60) system.

• Predicted lunar and solar eclipses and calculated the synodic period.

Planetary Observations

• Tracked five visible planets (Mercury, Venus, Mars, Jupiter, Saturn).

• Recorded in "astronomical diaries" for predictions.

Enuma Anu Enlil

• Collection of texts with records of celestial phenomena.

• Used for divination; linked celestial events to earthly occurrences.

Astronomical Knowledge Legacy

• Impacted Greeks and Islamic scholars in the Middle Ages.

• Greek astronomers, like Hipparchus and Ptolemy, refined Babylonian methods.

Egyptian Astronomy

• Primarily used for agriculture: relied on stars for seasonal flooding of the Nile.

• Significant star: Sirius (Sopdet) indicated agricultural events and religious festivals.

The Role of the Sun in Egyptian Astronomy

• Sun's journey represented life, death, rebirth in religion.

• Sun god Ra central; solar calendar included 12 months with additional days for a 365-day year.

The Role of the Moon

• Secondary importance to the Sun; god Thoth associated with the lunar calendar.

• Lunar eclipses deemed significant for religious purposes.

Influence on Later Civilizations

• Egyptian practices influenced Greek astronomy; Ptolemy built on this knowledge.

Stonehenge

• Proposed as an ancient astronomical site for solstices and eclipses.

• Constructed around 3000 to 1800 B.C. in alignment with celestial events.

Ancient Greek Astronomy

• Notable Figures: Thales, Anaximander, Plato, Aristotle, Hipparchus, Ptolemy.

• Shift from geocentric to heliocentric models began early, with Copernicus challenging past beliefs.

Key Concepts in Astronomy

• Diurnal motion: Daily movement of celestial objects due to Earth’s rotation.

• Annual motion: Movement of sun and stars due to Earth's revolution around the Sun.

Eclipse Types

• Lunar Eclipse: Occurs when Earth is between the Moon and the Sun.

• Solar Eclipse: Moon is between the Sun and Earth, temporarily blocking sunlight.

Planetary Facts

• Mercury: Closest to the Sun; fastest orbit.

• Venus: Brightest planet; rotates clockwise.

• Mars: Reddish; potential for life.

• Jupiter: Largest planet; thick cloud cover.

• Saturn: Known for its rings; second-largest.