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AST101H1 (135)
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# Astronomy Reading Notes.rtf

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Department
Astronomy & Astrophysics
Course
AST101H1
Professor
Michael Reid
Semester
Fall

Description
AST101 Reading Notes For: September 12th 2013 Where are we in the universe? • State the full “cosmic address” of Earth • Correctly use the terms planet, dwarf planet, moon, star, solar system, and galaxy • Correctly use astronomical distance units such Astronomical Units (AU) and light years (ly) • State the approximate sizes of important astronomical structures, such as planets, stars, solar systems, and galaxies, in AU and ly • Understand the relationship between astronomical distance and look-back time Sections1.1,1.2,1.4Figures1.1,1.4,1.5,1.10 ⁃ The full cosmic address of Earth is Earth, Solar System, Milky Way Galaxy, Local group, Local Supercluster ⁃ Solarsystem:consists of the sun and all the objects that orbits it such as, planets and their moons, and smaller objects such as rocky asteroids and icy comets ⁃ Galaxy: great island of stars in space which contains a hundred million and a trillion or more stars held together by gravity and orbiting a common centre ⁃ Stars: A large, glowing ball of gas that generates heat and light. Sun is a star just like the stars we see in our night sky ⁃ Planet: a large object that orbits around a star and shines because it reflects light from that star. something can only be considered a plant if it orbits a star, large enough for its gravity to make it round, and has cleared most object from its orbital path ⁃ DwarfPlanet: an object that meets the first two requirements of being a planet, but doesn't meet the third is considered a dwarf planet, like pluto ⁃ Moon(satellite): An object that orbits a planet. ⁃ AU is the earths average distance from the sun (about 150 million km). Describe distances in our solar system using AU. ⁃ ly is the distance light can travel within a year (10 trillion km). Use ly to describe the distance between stars and galaxies ⁃ Sizes: Earth 10^4 km, solar system 10^10 km, Milkyway 10^18 km, Local group 3x10^19 km, Local Supercluster 10^21 km ⁃ Lightyear is a unit of distance not time ⁃ Stars are so far away that their light takes years to reach us, this is why we measure their distance in ly ⁃ A star (sirius) can be located a certain number of ly away, this would mean that it takes that much time for light to travel between the star and earth (8 years). So the star you are seeing is not how the star looks today, but how it looked that many years ago (8 years ago) ⁃ "the farther away we look in distance, the further back we look in time" For: September 17th 2013 Apictorialtourofthesolarsystem,highlightingcurrentresearch • Correctly describe the shape and major motions (orbit, rotation) of objects in the solar system • Recognize the major patterns of motion in the solar system and, later, relate these to its formation mechanism • Distinguish between terrestrial and jovian planets • Identify key properties of each planet, emphasizing commonalities and exceptions • Become familiar with currently-active space missions to study the solar system Sections7.1-7.3Figures7.1,7.6Table7.1 ⁃ all the planets orbit the sun in the same direction and in nearly the same plane ⁃ all planets have nearly circular orbits going in the same direction in nearly the same plane ⁃ most large moons orbit their planets in the same direction, the direction of the sun's rotation ⁃ all planets orbit the sun in the same direction ⁃ Terrestrial planets: small in mass and size, close to sun, made of metal and rock, few moons no rings ⁃ Jovian planets: large mass and size, far from sun, made of H, He and Hydrogen compounds, rings and many moons ⁃ uranus rotates nearly on its side compared to its orbit and its rings and major moons share this sideways orientation ⁃ sun: thousand times as massive as everything else in the solar system combined, source of virtually al the light in our solar system ⁃ mercury: composed of rock and metal, no moons, 58.6 day rotation period means it rotates 3 times for every 2 of its 87.9 day orbits of the sun, daytime reaches 425c night reaches -150c ⁃ venus: composed of rocks and metals, no moons, rotates on its axis very slowly in the opposite direction of earth, venus & earth are similar in size and composition, ⁃ earth: composed of metal and rock, one moon, only planet in our solar system with oxygen, moon is larger than earth but not the largest moon ⁃ mars: composed of rock and metal, 2 moons, larger than mercury and the moon but half the earths size ⁃ jupiter: composed of hydrogen and helium, 67 moons, mass is 300 times that of earth, volume is 1000 times that of earth, like the sun (make up0 and has no solid surface, galilean moons ⁃ saturn: composed of hydrogen and helium, at least 62 moons, saturn orbits twice as far from the sun as jupiter, 2nd largest planet, no solid surface, known for rings, ⁃ uranus: composed of hydrogen, helium, and hydrogen compounds, has at least 27 moons, lies twice as far from the sun as saturn, smaller than jupiter or saturn but larger than dart, lacks solid surface, tipped on its side compared to other planets ⁃ neptune: composed of hydrogen, helium and hydrogen compounds, at least 13 moons, slightly smaller than uranus in size but high in density ⁃ inner 4 terrestrial outer 4 jovian ⁃ asteroids are rocky bodies that orbit the sun, comets also orbit the sun but are made up of ice mixed with rock ⁃ uranus rotates nearly on its side and venus rotates "backwards" ⁃ 1995 Galileo spacecraft dropped a probe into Jupiter ⁃ probes: spirit & opportunity rover landed on mars in 2004, curiosity rover in August 2012 ⁃ sample return missions: only sample return mission has been to the moon For Thursday September 19th 2013 Thenightsky,constellations,andseasons • Correctly use the terms such as constellation, celestial pole, celestial sphere, celestial equator, zodiac, and ecliptic • Describe the motion of the Earth, Sun, Moon, and stars relative to one another over time periods ranging from a day to a year • Explain why we can see different fractions of the celestial sphere from different locations on Earth and how this affects the placement of research telescopes • Describe the cause of the seasons and predict what seasons would be like on a planet with a different axial tilt than Earth's Sections2.1,2.2Figures2.3,2.4,2.9,2.10,2.12,2.14,2.15,2.20 ⁃ A constellation is a region of the sky with well defined borders; the familiar patterns of the stars help locate the constellations ⁃ Greeks imagined that stars and constellations lie on a great celestial sphere that surround earth ⁃ earth is actually in the centre of the celestial sphere ⁃ it allows us to make the sky as seen from earth ⁃ four special points and circles on the celestial sphere ⁃ north celestial pole is the point right over the earths north pole ⁃ south celestial pole is the point right over the earths south pole ⁃ celestial
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