There are about 6000 visible stars in the night sky. They are FAR. The light from our closest star, Proxima Centauri left 4 years ago!

Essential Question: What is evidence that the Earth revolves around the Sun? 1. Galileo 2. Copernicus 3. Kepler 4. Constellations 5. Parallax 28.2

Galileo Big Jupiter has several moons orbiting it! Venus has phases, so the planets are orbiting the Sun Galileo was constructing evidence to prove the heliocentric model

Copernicus Explains Retrograde Motion Planet's apparent path around sky. Fixed Stars 6 Sun 6 5 5 4 4 3 3 2 2 1 Earth 1 Mars orbit Earth is ORBITING the Sun faster, to it overtakes slower outer planets so they appear to slow down, move in reverse, and then move forward again with respect to the fixed stars.

Kepler’s observations/measurements: the Sun appeared to change diameter throughout the year Earth has an elliptical orbit around the Sun Not actually the diameter changing but the distance the sun is from the Earth that changed (perihelion: close aphelion: far) The shape of the Earth’s orbit around the Sun cannot be a circle if the distance changes

Aristotelian view has the earth and sky on fixed spheres The ancients imagined that the Earth was surrounded by a canopy of stars

Other Evidence

Find constellations that ONLY appear in the Summer sky. Find ones that ONLY appear in the Winter sky Summer Constellations Winter Constellation

Different Zodiac constellations appear in the sky at different times during the year

As we revolve around the Sun, the night time Earth faces a different direction in the sky at different months of the year, so we see different constellations. Evidence 3. The earth tilts AND revolves around the Sun so the Earth points to different direction of the night sky at different times of the year and sees different constellations

Celestial Portraits Human brains naturally create patterns. What do you see when you look at the clouds? The ancients did the same when they looked up at the sky.

Do you see a pattern in these stars?

Orion is only visible in the fall What constellation is this?? Orion Orion is only visible in the fall & winter

Tell a story Orion was a mythical hero and hunter, in his amorous pursuit of the Pleiades ( 7 daughters of the giant Atlas), the Gods placed them in the sky. And Orion chases after them in the sky for all eternity never to catch them. The Gods put Taurus the Bull to protect them the daughters. Orion has his trusty dogs Canis Major and Canis Minor to help him.

B A The cabin and trees haven’t moved, the OBSERVER moved from one side of the yard to the other side!

Parallax- the apparent shift in position of a star when the Earth is orbiting (the Sun) Evidence #5 Parallax

Stellar Parallax Interactive http://highered.mheducation.com/sites/007299181x/student_view0/interactives.html#

In this simulation, the blue star appears to be to the left of the distant, fixed background stars.

LARGEE If the distance to the target star is “close” then the parallax shift will appear to be

Earth Stars PHENOMENON: OBJECTS: MOTION:   PHENOMENON: What did you observe? What evidence do you have? OBJECTS: Define the system. What objects are interacting? MOTION: Describe the motion that in the model that explains your observations The constellations that are visible in the night sky change throughout the year. The 12 zodiac constellations change each 12 month in a cycle. The background of stars behind a familiar constellation changes over several months Earth Stars As the Earth orbits around the Sun, the night side of the Earth is a facing different part of the sky and seeing different stars (constellations). Parallax: the apparent shift in the position of stars because the Earth has change to a different location (the other side of the Sun/solar system) and is now viewing the stars from a different angle.