Exploration

EQ: How has mankind’s need to explore led to our current view

of the solar system?

Our First Views of the Universe

• Egyptians – need a way to predict the annual flooding of the Nile River

• Studied the star Sirius and noticed it was in the morning sky every spring shortly before the flooding began

Our First Views of the Universe

• Mayans – developed a calendar that was centuries before their time

• Observed the solstices

Our First Views of the Universe

• Stonehenge–Built in several stages–We don’t know who built it or exactly

why–It does have connections to the

summer and winter solstices

Our First Views of the Solar System: Reflect

Choose one of the reflections below to answer.•M: Restate the reason why Egyptians' exploration of the night sky was important.•I: Which of the three ancient societies would you have preferred to explore the sky with? Why?•U: What are the similarities in the explorations of the people who built Stonehenge and the Mayans?•S: Imagine you are looking up at the stars in 3,000 B.C. How can you explore them?

Beginning to Make Sense of the Universe

• Greeks observed the planets.–Called them wandering stars–Were aware of 5 planets – Mercury,

Venus, Mars, Jupiter, and Saturn

Beginning to Make Sense of the Universe

• Aristotle–Placed the earth at the center of the

solar system surrounded by 55 crystalline spheres – GEOCENTRISM–Earth did not move at all–Everything revolved around the Earth

Beginning to Make Sense of the Universe

• Ptolemy–Refined geocentric model of the solar

system–Epicycles – smaller circles around large

circles to help explain planetary motion–Messy way to explain the movement

of planets

Epicycles

• Used to explain retrograde rotation – the apparent backward movement of planets

Beginning to Make Sense of the Universe: Reflect

Choose one of the reflections below to answer.•M: Summarize the contributions of Aristotle and Ptolemy to our understanding of the solar system.•I: How would you feel if I told you the Earth really is the center of the solar system?•U: Contrast Aristotle and Ptolemy’s discoveries about the solar system.•S: Design a NASA mission patch dedicated to studying geocentrism.

The Revolution Begins

• Copernicus–Published Revolutionibus Orbium

Coelestium (On the Revolution of the Celestial Orbs) the year he died–Math based –Introduced the heliocentrism – the sun

is the center of the solar system

Copernican Solar System

The Revolution Begins

• Brahe – recorded many detailed astronomical observations – one of the first to make such detailed records

• Kepler – used Brahe’s data to develop his laws of planetary motion – planets orbit in ellipses

The Revolution Begins

• Galileo – first person to use a telescope to explore the

night sky; he became an expert at building refracting telescopes– Evidence for heliocentrism• Jupiter – four moons that revolved around

it – not Earth• Venus – goes through phases like the

moon• Sun – has spots and rotates

The Revolution Begins

• Newton–Developed a new kind of telescope to explore

with – reflector–Wrote the Three Laws of Motion to explain

the movements of the planets– Planets are kept in orbit around the sun by• Inertia – objects in motion stay in motion• Gravity – force of attraction between

objects

The Revolution Begins: Reflect

Choose one of the reflections below to answer.•M: What do you think were the two most important discoveries made by these astronomers?•I: Galileo’s findings were rejected the Catholic Church. How would you feel if you were Galileo?•U: If everyone around you believes in a geocentric universe, hypothesize what their reactions would be when you explain heliocentrism to them.•S: What would it be like to live on Jupiter and watch four moons orbit around your planet? What explorations would you conduct?

Our Growing Solar System

• Our continued need to explore has helped us learn more about the solar system and our views have changed over time because of that

Our Growing Solar System

• Uranus – discovered in 1781 by William Herschel using a telescope

• Ceres – discovered in 1801; initially called a planet; started a big debate that led to the creation of the asteroid category

• Neptune – discovered in 1846 using a telescope

Our Growing Solar System• Pluto – discovered in 1930 by Clyde Tombaugh• Kuiper Belt – discovered in 1992 – It’s the region beyond Neptune where Pluto is– Many other dwarf planets (Plutoids) are located

here• As our tools become more advanced, we continue

to explore and learn about our solar system– The Oort Cloud is a region beyond the Kuiper Belt– We’ve discovered a lot more about the moons of

other planets

Our Growing Solar System: Reflection

Choose one of the reflections below to answer.•M: What explorations led to Ceres no longer being considered a planet?•I: If you were in charge of deciding where our next unmanned space probe will go in the solar system, where would you send it?•U: Draw parallels between Ceres’ demotion from planet to asteroid and Pluto’s demotion from planet to dwarf planet.•S: Imagine your patient observations night after night lead to the discovery of a new planet. How would you announce your discovery to the world?

Organize the Exploration!

• Create an illustrated timeline to organize the explorations that led to our current understanding of the solar system.