ASTR 101 1st EditionExam # 1 Study Guide Lectures: 1 - 17Below I outline the key concepts of chapters 1-5 and 10. There are review questions here, and also includes vocabulary words.1.1 Our modern view of the universeHow big is the universe? Over 100 billion stars in the Milky Way galaxy. Our galaxy is one of more than 70 galaxies. How old is the universe? 7 billion years old1.2 The History of the UniverseWhat is our place in the universe? We are in the Milky Way galaxy, inside a local group of over 70 galaxies, in a local supercluster, in the universe. How do our lifetimes compare to the age of the universe? If the universe is 1 year old, human civilization is a few seconds old. 1.3 spaceship earthHow is earth moving in our solar system? --it rotates on its axis once a day and orbits the Sun at a distance once a year.How do galaxies move within the universe? --all galaxies move beyond the local group are moving away from us. The more distant they are, the farther they are away from us (Hubble’s law)Are we ever sitting still? NO! 2.1 Patterns in the skyWhat does the universe look like from earth? We’re on a celestial sphere divided into constellations. Why do stars rise and set? This is due to the earth’s rotation. Circumpolar 2.2 Reasons for SeasonsWhy do the constellations we see depend on the latitude and time of year? Our night sky points to different directions in space as the earth rotates, which affects the constellations we see. What causes the seasons? Why do we have 4 seasons? –the tilt on earth’s axisHow does the orientation of Earth's axis change in time? –Precession changes the orientation, but overallthe tilt remains about 23 ½ degrees2.3 The moonWhy do we see phases of the moon? The phases depend on the moon’s position relative to the Sun as it orbits the Earth.What causes eclipses? –lunar is when the earth’s shadow falls on the moon, solar is when the Moon blocks our view of the sun. Half of the moon is illuminated by the sun and half is dark. We see a changing combination of the bright and dark faces as the moon orbits earth2.4 Ancient mystery of planetsWhy was planetary motion so hard to explain? Apparent retrograde motionWhy did the ancient Greeks reject the explanation of planetary motion? They couldn’t detect stellar parallax3.1 Ancient roots of ScienceIn what ways do all humans use scientific thinking?How is modern science rooted in ancient astronomy? Ancient astronomers set the root for modern science3.2 ancient Greek ScienceModern science traces roots to the Greeks because they gave us modelsHow did the Greeks explain planetary motion? With the geocentric and Ptolemaic models3.3 Copernican revolutionHow did Copernicus, Tycho, and Kepler challenge the earth-centered model? **know these names!What are Kepler’s three laws of planetary motion?How did Galileo solidify the Copernican revolution?3.4 The nature of scienceHow can we distinguish science from nonscience? (There are three ways)What is a scientific theory? A simple but powerful model that explains observations and tests them4.1 describing motionHow do we describe motion? (Velocity, acceleration, momentum, force)How is mass different from weight? Mass is always the same, weight varies with strength of gravity. Weightless, free-fall4.2 Newton’s LawsHow did newton change our view of the universe?What are Newton’s three laws of motion?4.3 conservation lawsWhat keeps a planet rotating and orbiting the Sun? Conservation of angular momentumWhere do objects get their energy? (Kinetic, relative, potential)4.4 force of gravityWhat determines the strength of gravity? Universal law of gravitationHow does newton's law of gravity extend Kepler’s laws? (Bound orbits, unbound)How do gravity and energy together allow us to understand orbits? (Orbital energy, escape velocity)How does gravity cause tides? Tidal force is proportional to the distance cubed! If the distance of the moon is doubled, than the tidal force will be weaker by 8 times! 5.1 properties of light and matterWhat is light? (Electromagnetic wave, photons, radio waves, microwaves, infrared, visible light, ultraviolet, X rays, gamma rays)What is matter? (Atoms, protons, neutrons, electrons, isotopes, molecules)How do light and matter interact?5.2 learning from lightWhat are the 3 basic types of spectre? Absorption, emission, and continuous Hoe does light tell us the temperatures of planets and stars? The speed and distance of an object? Thermal radiation, Doppler Effect, blue and redshifts5.3 collecting light with telescopesHow do telescopes help us learn about the universe? Light-collecting area, angular resolution, interferometryWhy do we put telescopes in space? Light pollution and adaptive optics10.1 detecting planetsHow do we detect planets around other stars? Astrometric method, Doppler method10.2 natures of planets around starsWhat properties of extrasolar planets can we measure?How do extrasolar planets compare with planets in our solar system?10.3 formations of other planetary systemsDo we need to modify our theory of solar system formation? Somewhat, yes we do.Are planetary systems like ours