ASTRONOMERS HISTORY

ARISTOTLE

• 384-322 BCE
• He thought Earth was in the center of all things.

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ARISTARCHUS

• 310-230 BCE
• Preposed a model of the solar system
• Attempted to measure the relative distance to the moon and sun

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PTOLEMY

• 100-170 CE
• He believed that a celestial body traveled at a constant speed In a circle.

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NICOLAUS COPERNICUS

• 1473-1543
• Developed a theory that planetary paths were perfect circles.
• Sun in middle

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JOHANENES KEPLER

• 1571-1630
• 1st law; planetary orbits are ellipses with the sun
• 2nd law; move fast in orbit when closer to the sun
• 3rd law; timing of orbit to go around full sun.

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GALILEO

• 1564-1642
• He developed that Earth was not the only object that be orbited

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ISAAC NEWTON

• 1642-1727
• ⏬⏬Law of Universal Gravitational ⏬⏬
• States that all objects in the universe attract each other in gravitational force.

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EDWIN HUBBLE

• 1889 – 1953
• the recessional velocity of a galaxy increases with its distance from the earth.

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GEOCENTRIC

• This was developed to be alive that the earth is in the middle and stays still whole other planets orbit it.

HELIOCENTRIC

• This theory was developed to believe that the sun was in the middle while other planets orbited around it
• Present day is Heliocentric and is still the theory today.

KEPLERS 1ST LAW

• Planets orbit in an ellipse with the sun at one focus
• (^Elliptical Orbits)

KEPLERS 2ND LAW

• Planets sweeps out equal areas at equal times
• Perihelion- planet moves faster
• Aphelion- planet sweeps out a long narrow areas

KEPLERS 3RD LAW

• There is a mathematical relationship to a planets period of revolution and it's distance from the sun
• (O)^2=(D)^3