PHYS 1062 1st EditionExam # 1 Study Guide Chapters: 1 – 3, 5 - 7Chapter 1● Astronomy: study of the universe, the oldest science● Light travels through space and delivers information from stars● The universe consists of all space, time, energy, and matter● Beginnings of astronomy: civilization believed in a geocentric philosophy● 250 BC: Aristarchus hypothesizes that the earth moves around the sun● Early 20th Century: discovered the galaxy has a galactic center that the sun orbits ● Modern day: our galaxy is moving toward the Andromeda Galaxy ● Entire universe is expanding ● Earth is a terrestrial planet within our solar system, all others are not, both orbit sun and reflect its light● Sun: a star, glowing ball of gas that generates energy (light & heat) through nuclear fusion in its core, its gravity holds planets in orbit and defines size/shape of solar system, its solar winds flow charged particles that have escaped the sun to interact with magnetic fields, atmospheres, and sources of solar system objects● Solar System: consists of sun at center and its orbiting objects, such as eight planets that have forces strong enough to hold moons, dwarf planets, and other small objects like meteor and asteroids and dust● Dwarf planets: small planets that trail after larger ones● Uses scientific notation & the metric system to measure1 km = 1000 m = 1x10^3g & cm^3, density = g/cm^3earth’s radius = 6378 kmsolar radius = 7x10^5 km1 au = 1.5x10^8 km (earth to sun)1 ly = 63,000 au = 3x10^5 km/s● Nearest star to sun is Proxima Centauri, 4.2 ly away● We study the universe by studying light, from distant stars and galaxies which takes manyyears to reach our visible sky● Calculating light years: distance = speed x time (speed = distance/time)● Speed is constant at 3x10^13● 1 yr = (365 days) x (24 hr/day) x (60 min/hr) x (60 s/min)● 1 yr = 9,460,000,000,000 km = 9.46x10^12 km● At 1 year, light travels at the constant speed, covering 10x10^12 km of distanceThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.● It takes time for light to travel through space, the farther away we look in distance means we’re looking farther back in time● The speed of light limits the portion of the universe that we can see● The universe was born ~14 billion years ago, so we cannot see any light before 14 billion years ago because it hadn’t traveled before its birthChapter 2● Science: an attempt to explain what we observe in nature● Science is based on scientific evidence that can be observed/tested without any contradictions or holes ● Hypothesis: single assertion or conjecture that must be tested by making observations or performing experiments● Theory: system of rules and principles that can be applied in a variety of circumstances, can be tested, expanded and generalized● Natural Law: theory that has been refined, tested, and confirmed so often that scientists have complete confidence that it is a law of nature● Scientific Model: carefully devised mental conception of how something works, can be abstract, mathematical, or mechanical, based on assumptions● North Star (Polaris) is kind of like the center of the Celestial Sphere with stars and constellations seem to be rotating counterclockwise around it● Constellations: believed to be images by ancient people● Hipparchus (160-127 BC) first introduced the magnitude scale for star brightness● Distance between two stars on the Celestial Sphere can be given by the difference between directions of which we see them, measured in angles● Zenith: point in the sky directly above observer● Horizon: circle around us where the dome of the sky meets the earth● Meridian: great circle on Celestial Sphere that passes through an observer’s zenith and the north (or south) celestial poles● Polaris: brightest star in galaxy, currently near axis of earth, always visible from earth● The earth rotates on its axis and orbits around the sun, so its position in the universe is always changing, therefore our view of the Celestial Sphere is as well● Zodiacal Constellations: the constellations along the Ecliptic, stars that were “connected” into images that were given significance by ancient Greeks● Earth’s distance from the sun influences temperatures and climates, which also gives wayto seasons as it orbits the sun, the north is slightly tilted towards the sun during the summer season whereas it slightly tilts away during the winter, the elliptical orbit also contributes to seasons because Earth is farther from sun in winter and closer in summer ● Earth is tilted about 23.5 degrees, seasons are caused by a varying angle of incidence of the sun’s rays, we receive more energy from the sun when it is shining onto the Earth’s surface under a steeper angle of incidence, sun sets faster during winter whereas the sun rises at its highest during the summer, the winter angle causes longer shadows● Moons gravity helps keep the Earth in the same position and at its angle● During the summer, the sun’s energy is concentrated above the Equator and horizon, whereas the sun’s energy is concentrated below during Winter● Equinox: equal night, points where ecliptic intersects with the Equator (autumnal & vernal)● Solstice: sun stand, point where sun reaches its greatest distance from either poles (summer & winter)● Precession: gravity is pulling on a slanted top, wobbling around vertical axis● Milankovitch Hypothesis: changes in all three of these aspects, eccentricity of orbit, precession, and inclination of axis, are responsible for long-term global climate change (ice ages & warmer periods)Chapter 3● The moon rises and sets along Celestial Sphere, takes about a month to orbit Earth which is called a Sidereal Period or Synodic Period, reflects the light of the sun to Earth, we always see the same side of the moon● Sidereal Period: relative to a star of choice, it’s the length of time for the moon to orbit from said star, around Earth, and back to star, 27.32 days● Synodic Period: relative to the Sun, it’s length of time for the moon to orbit from the Sun (New Moon), around the Earth, and back to the Sun (New Moon), 29. 53 days● Lunar Phases: as the Moon moves through the sky, its appearance changes based on its position relative to the Sun’s rays, this cycle is also as long