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Chapter 1

Chapter One

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Department
Astronomy
Course
AS101
Professor
Victor Aurora
Semester
Winter

Description
AS101 Chapter 1.1: Solar System to Galaxy to Universe Week One th January 6 Learning objectives • Mass and energy • Astronomical objects • Within the different levels of structure The Cosmos • Mostly vacuum (empty space) • Everything we can possibly see is a tiny fraction • Why does it seem like there are so many objects in space? If it’s mostly empty The Sun is our Star • Massive ball of glowing gas that generates energy through nuclear fusion (mostly hydrogen gas or vapour that is being smooshed together making energy) • About 100x as wide as the Earth • Indirect source of almost all energy on Earth Planets are less massive than stars (Rules of a planet) • 1. Non luminous and spherical (insert photos of planets) o Not glowing but still in a spherical shape • 2. In orbit around a star • 3. “cleared the neighborhood” of other objects • Exoplanets o Over 900 planets confirmed to be orbiting other stars o Thousands of “candidate” exoplanets, observed by the Kepler Space Telescope o Some planets have satellites  An object in orbit around a planet  Natural satellites are also known as “moons” o Asteroid: a small, rocky object orbiting a star  Not spherical hint that it’s not that massive and gravity isn’t pulling it together o Comet: a small, icy object that orbits the sun Galaxies: “cities” of the Cosmos • A large system of dark matter, stars, gas, and dust, all bound together by their combined gravity • Pictured is the spiral M83 (insert photo) • Nat all galaxies are spirals • Nebulae o Clouds of gas and/or “dust” within galaxies o Raw materials for new stars from previous generations • Star clusters o Open clusters: 1000s of stars o Globular clusters: 100000s ……………………………. • Galaxy groups and clusters o A group of galaxies (a few dozen up to thousands) all held together gravitationally) • Many clusters form a supercluster which make the cosmic web (insert photo) Summary • The universe is mostly made of invisible matter and energy • Matter the Universe is structured on many scales • The Universe is mostly empty space • But the Universe is a very big place January 8 th RECAP • We have had an intro to the make-up contents, and overall structure of the Universe o There is a LOT of space out there Learning Objectives • Scales of distance and time using scale models • Scientific Notation • Speed of light as they were in the past Models in Science • In general, a model is something that represents reality • A scientific model: a hypothesis that describes reality and has withstood observational or experimental tests • We can also develop conceptual models to help us think about how nature works • Today we will be looking at some scale models* (miniature or shrunk down versions) Scale Model: The Solar System • How do the sizes of the planets compare to the distances between them> • What if we shrunk the solar system by a factor about 60 billion? • Key Idea: The sizes of the planets are tiny compared to the distances between them The Astronomical Unit • We can specify distances in the Solar System by comparing them to the average Earth-Sun distance • 1 AU: 150 000 000 000km • Astronomical Unit (AU): the average distance from Earth to the Sun (1 AU) o Which is 1.5⁸ x 10km or 1.5₁₁ x 10m o Another ex. Average distance from Venus to the Sun is 0.7 AU o Mars is 1.5 AU from the Sun • A planet is twice as far from the Sun would be 2 AU away Scientific Notation • What I we just specified how many
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