Introduction to AstronomyIntroduction to Astronomy

Section 1.1Section 1.1

Intro:Intro:

What is Astronomy?What is Astronomy? What is Astrology?What is Astrology?

Big IdeasBig Ideas

#1 Space exploration has generated valuable #1 Space exploration has generated valuable knowledge but at enormous cost.knowledge but at enormous cost.

#2 Different types of celestial objects in the solar #2 Different types of celestial objects in the solar system and universe have distinct properties system and universe have distinct properties that can be investigated and quantified.that can be investigated and quantified.

#3 People use #3 People use observationalobservational evidence of the evidence of the properties of the solar system and the universe properties of the solar system and the universe to develop theories to explain their formation to develop theories to explain their formation and evolution.and evolution.

What is …What is …

Observational evidence?Observational evidence? Information collected from repeated Information collected from repeated

observations, unlike data that is directly observations, unlike data that is directly measuredmeasured

Ex: the Sun sets every night and rises every Ex: the Sun sets every night and rises every morningmorning

Ex: the seasons cycle winter through spring, Ex: the seasons cycle winter through spring, summer and fallsummer and fall

What is …What is …

A Calendar?A Calendar?A table or chart that organizes days into a A table or chart that organizes days into a

schedule of large units of time, such as weeks, schedule of large units of time, such as weeks, months, seasons or yearsmonths, seasons or years

Calendar comes from the Latin word kalendae, Calendar comes from the Latin word kalendae, which was the word for the first day of every which was the word for the first day of every monthmonth

What is a calendar?What is a calendar?

Why was it important to establish a Why was it important to establish a calendar?calendar?To predict important eventsTo predict important events

Eg) Seasons and temperature change (floods, Eg) Seasons and temperature change (floods, droughts), farming, huntingdroughts), farming, hunting

Where did it come from??Where did it come from??Ancient Astronomers!Ancient Astronomers!

Prehistoric AstronomyPrehistoric Astronomy

Prehistoric cultures left behind artifacts Prehistoric cultures left behind artifacts that refer to astronomythat refer to astronomyPyramidsPyramidsStonehenge Stonehenge

Mayan Pyramids & stonehenge

Insert pictures

Ancient AstronomyAncient Astronomy

Deities (gods) together played a significant role in Deities (gods) together played a significant role in early astronomyearly astronomy

Gods ruled the sky; storms or natural disasters were Gods ruled the sky; storms or natural disasters were interpreted as the gods wrathinterpreted as the gods wrath

Celestial priests and priestesses studied the sky ‘to Celestial priests and priestesses studied the sky ‘to maintain order’maintain order’

They focused on They focused on celestial objectscelestial objects: any object that : any object that exists in spaceexists in space

Ancient AstronomyAncient 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

Ancient AstronomyAncient Astronomy

From these observations, early ideas From these observations, early ideas about the motions of the planets were about the motions of the planets were formed, and the nature of the Sun, Moon formed, and the nature of the Sun, Moon and the Earth in the universe were and the Earth in the universe were explored philosophically. explored philosophically.

The Earth was believed to be the center of The Earth was believed to be the center of the universe with the Sun, the Moon and the universe with the Sun, the Moon and the stars rotating around it. This is known the stars rotating around it. This is known as the as the geocentric model of the universe. geocentric model of the universe.

Ancient AstronomyAncient Astronomy

Our current calendar year is determined Our current calendar year is determined by how long it takes Earth to revolve by how long it takes Earth to revolve around the sunaround the sunRevolution = the motion of an object in orbit Revolution = the motion of an object in orbit

about another objectabout another objectOne 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 Add up all the # of days in each month … how

do we account for this?do we account for this?Leap year – every 4 years an extra day is Leap year – every 4 years an extra day is

added in Februaryadded in February

Early ClocksEarly Clocks

One day is the average time it takes for One day is the average time it takes for Earth to make one rotation (with respect to Earth to make one rotation (with respect to the sun)the sun)Rotation = the turning of an object on its axisRotation = the turning of an object on its axis

How do we mark the passing of time during How do we mark the passing of time during the day?the day?ClockClockShadows cast by pillars or sticks in the ground Shadows cast by pillars or sticks in the ground

showed time passingshowed time passingWhy would they use shadows?Why would they use shadows?

Early ClocksEarly Clocks

Pillars progressed to Pillars progressed to sundialssundials

Earth as a SphereEarth as a Sphere

Ancient Egyptians and Inuit thought that Ancient Egyptians and Inuit thought that the Earth was flat the Earth was flat

Greek philosophers hypothesized that Greek philosophers hypothesized that Earth was a sphere and flatness was an Earth was a sphere and flatness was an illusionillusion

1.1. Disappearing shipsDisappearing ships

2.2. Changing skyChanging sky

3.3. Earth’s curved shadowEarth’s curved shadow

Earth as a Sphere

Disappearing Ships

Earth as a Sphere

The Changing Sky

Earth as a Sphere

Earth’s Curved Shadow

Zodiac SignsZodiac SignsAs the Earth orbits the Sun, from our As the Earth orbits the Sun, from our

perspective the Sun follows the ecliptic perspective the Sun follows the ecliptic The circumference of the celestial sphere in the The circumference of the celestial sphere in the

plane of the Earth’s orbit plane of the Earth’s orbit

There are 12 constellations on the ecliptic There are 12 constellations on the ecliptic (apprx. 1 per month)(apprx. 1 per month)

ZodiacZodiac

ZodiacZodiac

Each month the Sun moves in front of a different Each month the Sun moves in front of a different zodiac constellation.zodiac constellation.

Your sign of the zodiac is the constellation that Your sign of the zodiac is the constellation that was behind the Sun when you were born.was behind the Sun when you were born.

You can best see your zodiac constellation in the You can best see your zodiac constellation in the night sky about 6 months after your birthday.night sky about 6 months after your birthday.

A great deal of superstition surrounds the zodiac. A great deal of superstition surrounds the zodiac. This is known as astrology, and is related to This is known as astrology, and is related to neither science nor astronomy.neither science nor astronomy.

Zodiac signsZodiac 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)

ZodiacZodiac

ZodiacZodiac

Modern Day ZodiacsModern Day Zodiacs

Astronomer TimelineAstronomer Timeline