Welcome to A100 Instructor: Caty Pilachowski Assoc. Instructor: Nathalie Haurberg Today’s APODAPOD  Read Preview – Cosmic Landscape  1 st Homework due Sept. 12 Solar System The Sun Today

Where will we start? –The night sky –Learning to see with an astronomical eye –Size and scale Where are we going? The origin and evolution of planets and the Solar System The Earth’s environment Planets around other stars

A100 - Solar System  On the back of note card…  draw a dot in the center of the paper - label it as the Sun  draw and label the Earth’s orbit around the Sun, as if you were looking down on the Solar System from above  add and label the orbits of as many other planets and Solar System components as you can

The Sun The planets and moons Dwarf planets (asteroids & plutoids) Cometary bodies Meteoroids Dust Plasma (hot gas) What’s in the Solar System?

The Sun Radius: 700,000 km Diameter: 1,400,000 km (about 100 x the diameter of Earth) Mass: 300,000 x mass of Earth

Earth Radius: 6400 km Distance from Sun: 150,000,000 km 1 AU, 8 light minutes Moon ¼ Earth’s radius distance ~400,000 km Of course, the PLANETS

Units of Distance  kilometers  for radii of the planets, the Sun, etc.  astronomical units  for distances between solar system bodies  definition: the average distance between the Earth and Sun (~150,000,000 km = 1.5 x 10 8 km)  light years  for distances between stars and galaxies  definition: the distance light travels in one year (~10,000,000,000,000 km = km = 63,000 AU)

What about poor Pluto? What is a planet? What must be considered to decide if Pluto is a planet?

What defines a planet?  Round (enough mass for strong gravity)  Dominant body (tosses smaller bodies out of the Solar System)  Orbits the Sun NOT TO SCALE!!!

Pluto’s Basic Data Diameter:0.18 Earth diameters Mass0.002 Earth masses In SS plane?NO! …orbit tilts 17º Circular Orbit?NO! …e=0.25 Other planets < 7º Other planets e < 0.2

Guidance from the Discovery of Ceres 1801 Planet suspected between Mars and Jupiter Campaign organized to search the sky Ceres - the first (and largest) asteroid to be found A planet…. or not? Image from Hubble

Ceres: Not! Too small Many more asteroids found shortly thereafter Tens of thousands known today PallasJuno Hubble images

So What Is Pluto? One of many dwarf planets (plutoids) that orbit the Sun outside the orbit of Neptune

The Outer Solar System Our Solar System is surrounded by a halo of ice bodies – plutoids and cometary bodies

What about that plasma? The Solar Wind: Energy is released in the form of light, sub-atomic particles, and magnetic fields The particles are protons, electrons, and helium nuclei moving out from the Sun at a speed of about 500 km/sec

The Solar Wind The solar wind flows from the Sun and envelopes the Earth and other planets The charged particles distort the Earth’s magnetic field and produce geo-magnetic storms that disrupt the Earth’s environment

The Outer Limits Now in the distant solar system, NASA spacecraft continue to characterize the outer solar system environment and search for the heliopause boundary, the outer limits of the Sun's magnetic field and outward flow of the solar wind

Outer limits of SS Oort Cloud The Environment of the Solar System  The Sun entered an interstellar cloud of mixed plasma and gas about years ago  The directions of motion of the Sun and the cloud suggest that our Solar System will be in this cloud for the next million years  The surrounding interstellar cloud will shrink the heliosphere to a smaller radius  The clouds are so thin that we see right through them

The “Local Bubble” On a larger scale, the Sun is surrounded by a large bubble of low density gas, on the edge of one the Galaxy’s spiral arms

Our Sector of the Galaxy The Sun lies along one of our Galaxy’s spiral arms, known as the Orion Arm

View of the Milky Way Galaxy Our Milky Way galaxy contains two hundred billion stars The Sun is about 26,000 light years from the center

Our Milky Way Galaxy is part of a small cluster of about 3 dozen galaxies

Virgo Supercluster Our Local Group of galaxies is part of a larger Supercluster of galaxy groups

Galaxies and clusters of galaxies collect into vast streams, sheets, and walls of galaxies

Put these objects in the correct order from the nearest to the farthest from Earth a)The Sun, the Milky Way, Alpha Centauri, Saturn, the Andromeda Galaxy b)The Sun, Alpha Centauri, Saturn, the Andromeda Galaxy, the Milky Way c)The Sun, Saturn, Alpha Centauri, the Milky Way, the Andromeda Galaxy d)Saturn, the Sun, Alpha Centauri, the Milky Way, the Andromeda Galaxy

Overview Organization and course goals

Who’s in the class? Freshmen? Sophomores? Juniors? Seniors? Other? School…? Major…?

Science and the Distribution Requirement  Science and technology drive much of modern life  Jobs!  Informed voters make better decisions

Why are you taking this class?

I need to take a science class and astronomy sounded easy/fun I've always been interested in astronomy I had space in my schedule for another course and thought I'd try astronomy I want to be a science teacher I'm thinking of minoring/majoring in astronomy My friend is taking the class, so I'm taking it with her/him. This is supposed to be an easy course, and I need to bring up my GPA This course was recommended by a friend I want to amaze my friends and family with my knowledge of the night sky.

Course Organization  Syllabus/OncourseOncourse  Text + Web  Lecture Notes  Written Homework  Quizzes  Observing Activities  Exams & Final Office Hours Caty P.: Thursday, 11-noon SW by appointment Nathalie Haurberg: Mon. 2:30-3:30, SW313 + Thurs. 5:30-6:30 Starbucks on Indiana Ave

GRADES  Quizzes (20%, best 8 of 10)  Homework (20%, best 8 of 10)  Observing Activities (10%, four required)  3 Exams (10% + 10% + 10%)  Final Exam (20%)

Course Goals  Science as discovery  Use real astronomical data  Learn about the process of science View of Saturn’s Rings from the Cassini Spacecraft

One question I’ve always had about astronomy is…

Kirkwood Observatory Open TONIGHT Great time to see Jupiter 9:30-11:30, weather permitting Call hotline ( ) to confirm open West end of Dunn’s Woods

ASSIGNMENTS this week  Read “Cosmic Landscape”  Quiz on essential facts and scientific notation on Monday  Rooftop Sky Viewing Sept. 10  1 st HW due Sept. 12 Dates to Remember