1. Introduction to Astronomy Section 1.1 Section 1.1

2. Intro: What is Astronomy? What is Astronomy? What is Astrology? What is Astrology?

3. Big Ideas #1 Space exploration has generated valuable knowledge but at enormous cost. #1 Space exploration has generated valuable knowledge but at enormous cost. #2 Different types of celestial objects in the solar system and universe have distinct properties that can be investigated and quantified. #2 Different types of celestial objects in the solar system and universe have distinct properties that can be investigated and quantified. #3 People use observational evidence of the properties of the solar system and the universe to develop theories to explain their formation and evolution. #3 People use observational evidence of the properties of the solar system and the universe to develop theories to explain their formation and evolution.

4. What is … Observational evidence? Observational evidence? Information collected from repeated observations, unlike data that is directly measured Information collected from repeated observations, unlike data that is directly measured Ex: the Sun sets every night and rises every morning Ex: the Sun sets every night and rises every morning Ex: the seasons cycle winter through spring, summer and fall Ex: the seasons cycle winter through spring, summer and fall

5. What is … A Calendar? A Calendar? A table or chart that organizes days into a schedule of large units of time, such as weeks, months, seasons or years A table or chart that organizes days into a schedule of large units of time, such as weeks, months, seasons or years Calendar comes from the Latin word kalendae, which was the word for the first day of every month Calendar comes from the Latin word kalendae, which was the word for the first day of every month

6. What is a calendar? Why was it important to establish a calendar? Why was it important to establish a calendar? To predict important events To predict important events Eg) Seasons and temperature change (floods, droughts), farming, hunting Eg) Seasons and temperature change (floods, droughts), farming, hunting Where did it come from?? Where did it come from?? Ancient Astronomers! Ancient Astronomers!

7. Prehistoric Astronomy Prehistoric cultures left behind artifacts that refer to astronomy Prehistoric cultures left behind artifacts that refer to astronomy Pyramids Pyramids Stonehenge Stonehenge

8. Mayan Pyramids & stonehenge Insert pictures

9. Ancient Astronomy Deities (gods) together played a significant role in early astronomy Deities (gods) together played a significant role in early astronomy Gods ruled the sky; storms or natural disasters were interpreted as the gods wrath Gods ruled the sky; storms or natural disasters were interpreted as the gods wrath Celestial priests and priestesses studied the sky ‘to maintain order’ Celestial priests and priestesses studied the sky ‘to maintain order’ They focused on celestial objects: any object that exists in space They focused on celestial objects: any object that exists in space

10. Ancient Astronomy Mesopotamians were among the first astronomers A scientist who studies the night sky 6000 years ago they established a calendar Organized agriculture was born and led to other jobs with specialized skills They began mapping the positions of stars and planets

12. Ancient Astronomy From these observations, early ideas about the motions of the planets were formed, and the nature of the Sun, Moon and the Earth in the universe were explored philosophically. From these observations, early ideas about the motions of the planets were formed, and the nature of the Sun, Moon and the Earth in the universe were explored philosophically. The Earth was believed to be the center of the universe with the Sun, the Moon and the stars rotating around it. This is known as the geocentric model of the universe. The Earth was believed to be the center of the universe with the Sun, the Moon and the stars rotating around it. This is known as the geocentric model of the universe.

13. Ancient Astronomy Our current calendar year is determined by how long it takes Earth to revolve around the sun Our current calendar year is determined by how long it takes Earth to revolve around the sun Revolution = the motion of an object in orbit about another object Revolution = the motion of an object in orbit about another object One year (or revolution) is 365.24 days long! One year (or revolution) is 365.24 days long! Add up all the # of days in each month … how do we account for this? Add up all the # of days in each month … how do we account for this? Leap year – every 4 years an extra day is added in February Leap year – every 4 years an extra day is added in February

14. Early Clocks One day is the average time it takes for Earth to make one rotation (with respect to the sun) One day is the average time it takes for Earth to make one rotation (with respect to the sun) Rotation = the turning of an object on its axis Rotation = the turning of an object on its axis How do we mark the passing of time during the day? How do we mark the passing of time during the day? Clock Clock Shadows cast by pillars or sticks in the ground showed time passing Shadows cast by pillars or sticks in the ground showed time passing Why would they use shadows? Why would they use shadows?

15. Early Clocks Pillars progressed to sundials Pillars progressed to sundials

16. Earth as a Sphere Ancient Egyptians and Inuit thought that the Earth was flat Ancient Egyptians and Inuit thought that the Earth was flat Greek philosophers hypothesized that Earth was a sphere and flatness was an illusion Greek philosophers hypothesized that Earth was a sphere and flatness was an illusion 1. Disappearing ships 2. Changing sky 3. Earth’s curved shadow

17. Earth as a Sphere Disappearing Ships

18. Earth as a Sphere The Changing Sky

19. Earth as a Sphere Earth’s Curved Shadow

20. Zodiac Signs As the Earth orbits the Sun, from our perspective the Sun follows the ecliptic As the Earth orbits the Sun, from our perspective the Sun follows the ecliptic The circumference of the celestial sphere in the plane of the Earth’s orbit The circumference of the celestial sphere in the plane of the Earth’s orbit There are 12 constellations on the ecliptic (apprx. 1 per month) There are 12 constellations on the ecliptic (apprx. 1 per month)

21. Zodiac

22. Zodiac Each month the Sun moves in front of a different zodiac constellation. Each month the Sun moves in front of a different zodiac constellation. Your sign of the zodiac is the constellation that was behind the Sun when you were born. Your sign of the zodiac is the constellation that was behind the Sun when you were born. You can best see your zodiac constellation in the night sky about 6 months after your birthday. You can best see your zodiac constellation in the night sky about 6 months after your birthday. A great deal of superstition surrounds the zodiac. This is known as astrology, and is related to neither science nor astronomy. A great deal of superstition surrounds the zodiac. This is known as astrology, and is related to neither science nor astronomy.

23. Zodiac signs Known as the signs of the zodiac: Known as the signs of the zodiac: Aries the ram, Aries the ram, Taurus the bull, Taurus the bull, Gemini the twins, Gemini the twins, Cancer the crab, Cancer the crab, Leo the lion, Leo the lion, Virgo the virgin, Virgo the virgin, Libra the scales, Libra the scales, Scorpius the scorpion, Scorpius the scorpion, Sagittarius the archer, Sagittarius the archer, Capricornus the goat, Capricornus the goat, Aquarius the water carrier, Aquarius the water carrier, Pisces the fish) Pisces the fish)

24. Zodiac

25. Zodiac

26. Modern Day Zodiacs

27. Astronomer Timeline 6 th Century B.C. Geocentric model 4 th Century B.C. Geocentric model refined 2 nd Century A.D “epicycles” 1545 Copernicus heliocentric model Early 1600’s Johann Kepler - planets travel in ellipses around the Sun Galileo Mid 1600’s Isaac Newton – gravitational force