Transcript Galileo
Agenda LECTURE: •Review of Last Week •More Models of the Solar System (Gravitation and the Motion of the Planets) & (if time) Cosmic Distances and Tutorial on Parsec/Parallax LAB: Roof – Setting Circles or Indoor – Retrograde Motion and Privileged Planet (bumped to next week, weather pending) Review of History of Astronomy & Models of the Solar System Ptolemy Copernicus (Tycho) Brahe (Johannes) Kepler Galileo (Galilei)* (Issac) Newton* Mnemonic (credit to my brilliant student & in order from oldest to most recent): PCBKGN [Popular Captain Bryce King Goes Nowhere] *We’ll learn about these dead white guys today. Out of the Scientists listed above, who supported the geocentric model versus the heliocentric model? Review of Kepler’s Laws • First Law: • Second Law: • Third Law: Review for Setting Circles Lab 1) What is the declination at the North Pole? 2) What is the declination at the equator? 3) What sign (+ or -) are the declinations in the South celestial pole? 4) Show angle of declination for the star above. Declination (like latitude) is measured in degrees north or south of the Celestial equator. Right Ascension, RA (like longitude) is measured in units of hours, minutes, and seconds The Vernal Equinox is the position of the Sun on the first day of Spring. •For RA, the 360 degrees is divided up over 24 hours with each hour being 60 minutes and a minute is 60 seconds. •Usually small angular measurements are measured in arcseconds …as you will see in the Parsec/Parallax Tutorial. Review of Right Ascension & Declination for Setting Circles Lab Week 8: More Models of the Solar System (Gravitation and the Motion of the Planets) – A.K.A More DEAD WHITE GUYS! The great scientist Galileo made discoveries that strongly supported a heliocentric cosmogony Galileo - 1564-1642 - 1. 2. 3. 4. 5. 6. 7. Probably died a virgin Was a priest and Lawyer Had artificial wooden and silver noses Probably died of Mercury poisoning Rumored to have died when his bladder burst Was blind at the time of his death Was labeled a heretic by the church Galileo - 1564-1642 - 1. 2. 3. 4. 5. 6. 7. Probably died a virgin Was a priest and Lawyer Had artificial wooden and silver noses Probably died of Mercury poisoning Rumored to have died when his bladder burst Was blind at the time of his death Was labeled a heretic by the church Galileo - 1564-1642 is known for - 1. First observations of the sun 2. First sun centered scientific model of the solar system or universe 3. Being the world’s best naked-eye astronomer 4. Creating first a theoretical model to explain planetary motions 5. Creating first a theoretical model for explaining gravity Galileo - 1564-1642 is known for - 1. First observations of the sun 2. First sun centered scientific model of the solar system or universe 3. Being the world’s best naked-eye astronomer 4. Creating first a theoretical model to explain planetary motions 5. Creating first a theoretical model for explaining gravity In 1609 Galileo learned of the invention of the telescope (which magnified objects by 3 times), he made alterations to it and developed one that magnified 20 times. What did he then discover with his telescope? 1. Craters on the Moon 2. Four Galilean Moons of Jupiter 3. Phases of Venus 4. Discovery of Sunspots & Rotation of Sun 5. He concluded that numbers 1 – 4 above supported the Copernican Model that the Earth and Planets revolve about the Sun (i.e. Heliocentric Model). Prior to this it was believed that the universe was Geocentric. Galileo was the first astronomer to aim a telescope at the moon and the first to see any of its craters and mountains. The Moon • The moon has craters. • The moon is not a perfect heavenly body. Sunspots • The Sun is not a perfect heavenly body. • The Sun rotates about its own axis, as evidenced by the sunspots moving. This is a view from space of X-rays on the Sun taken by satellites, showing solar flares, prominences, gases etc. Galileo’s discoveries of the phases of Venus with his telescope showed that Venus must orbit the Sun and strongly supported a heliocentric model Venus is clearly smallest when it in the full phase and largest when it is in the new phase. Then Venus must be very far from Earth when it is in the full phase and quite closes to Earth when in the new phase – which supports the argument that Venus is orbiting the Sun not Earth. Galileo’s telescope revealed phases of Venus which could only occur IF Venus orbits the Sun. Galileo’s telescope revealed phases of Venus which could only occur IF Venus orbits the Sun. Galileo’s telescope revealed phases of Venus which could only occur IF Venus orbits the Sun. Galileo’s telescope revealed that Jupiter had moons which orbited Jupiter instead of Earth. Did Galileo go blind from observing the Sun? IN MEMORY OF GALILEO http://brunelleschi.imss.fi.it/gensched a.asp?appl=SIM&xsl=biografia&ling ua=ENG&chiave=300251 Isaac Newton (1642 – 1727) The Baddest Dead White Guy of Them All Isaac Newton (1642 – 1727) - 1. 2. 3. 4. 5. 6. 7. Probably died a virgin Was a priest and Lawyer Had artificial wooden and silver noses Probably died of Mercury poisoning Rumored to have died when his bladder burst Was blind at the time of his death Was labeled a heretic by the church Isaac Newton (1642 – 1727) - 1. 2. 3. 4. 5. 6. 7. Probably died a virgin Was a priest and Lawyer Had artificial wooden and silver noses Probably died of Mercury poisoning Rumored to have died when his bladder burst Was blind at the time of his death Was labeled a heretic by the church Isaac Newton (1642 – 1727) is known for - 1. First observations of the sun 2. First sun centered scientific model of the solar system or universe 3. Being the world’s best naked-eye astronomer 4. Creating first a theoretical model to explain planetary motions 5. Creating first theoretical model for explaining gravity and ….. Isaac Newton (1642 – 1727) is known for - 1. First observations of the sun 2. First sun centered scientific model of the solar system or universe 3. Being the world’s best naked-eye astronomer 4. Creating first a theoretical model to explain planetary motions 5. Creating first theoretical model for explaining gravity and ….. Isaac Newton formulated three laws of motion and the law of gravitation – these laws describe the motion of our physical world Newton’s Three Laws of Motion First Law - A body remains at rest or moves in a straight line at a constant speed unless acted upon by an outside (net) force. Fnet 0, then a 0 Second Law – An object with a net Force Fnet on it will have an acceleration ( a ) related to its mass (m). Fnet ma Third Law - Whenever one body exerts a force on a second body, the second body exerts an equal and opposite force on the first body. Label the Examples below indicating if they exemplify the 1st, 2nd or 3rd Law of Newton 1. A rocket will coast in space along a straight line at constant speed. 2. A MAC truck and a motorcycle are being push started by the same person, how do their accelerations compare? 3. The recoil of a gun or a rocket being launched and firing through space. 4. A hockey puck glides across the ice at constant speed until it hits something. 5. The Bug and the Windshield – who is having the worst day? Did you know you are physically attracted to the person sitting next to you? Newton’s Law of Gravitation • Newton’s law of gravitation states: Two bodies attract each other with a force that is directly proportional the product of their masses and is inversely proportional to the square of the distance between them. Gm1m2 Fgrav 2 d m1 d m2 Newton’s Law of Gravitation • To figure out the gravitational force just multiply “G” by the mass of the two things together then divide by their separation distance, d (squared). m1 Gm1m2 Fgrav 2 d d m2 Newton’s Law of Gravitation • Newton’s law of gravitation states: Two bodies attract each other with a force that is directly proportional the product of their masses and is inversely proportional to the square of the distance between them. Fgrav Fgrav mEarth GmEarth myou d2 2 d Nm 11 24 6.67 10 5.97 10 kg m you 2 kg 2 6 6.38 10 m Fgrav gm you Myou g ~ 10 m/s2 “the acceleration of gravity on Earth’s surface” And g x m is your weight! Newton’s Laws and Kepler's Laws • Newton’s law of gravitation and his three laws of motion prove all of Kepler’s laws IF time permits, we may do some simple ROCKET SCIENCE! [Prove Kepler’s 3rd Law & determine the speed needed to get a satellite in an orbit of radius “r” about the Earth. (you are not accountable for this on the exam).] Newton's friend Edmund Halley predicted the comet would return in 1758 and it did! REVIEW Who was the “Greatest Naked-eye Astronomer” (i.e. no telescope) and what was one of his most valuable ways to measure distance? Parallax Tycho Brahe measured distances using parallax that disproved ancient ideas about the heavens • He observed a supernova in 1572 and with this showed that the heavens were both changing and had a dimension of distance; this troubled scholars who previously thought the heavens were unchanging. • He showed that comets were objects that occurred in the region of the planets, not in Earth’s atmosphere. Scientists use parallax to measure distances. Parsec/Parallax Tutorial (pg 35-37) • Work with a partner! • Read the instructions and questions carefully. • Discuss the concepts and your answers with one another. • Come to a consensus answer you both agree on. • If you get stuck or are not sure of your answer, ask another group. • If you get really stuck or don’t understand what the Lecture Tutorial is asking, ask one of us for help.