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Yesterday an earthquake hit Haiti. Initial estimates are that “hundreds of thousands” have died. More are homeless. Consider making a contribution to assist in the recovery. Here are a few agencies that will need help: Oxfam: www.oxfamamerica.org Red Cross: www.redcross.org Doctors Without Borders: doctorswithoutborders.org UNICEF: unicefusa.org/haitiquake Save the Children: savethechildren.org If you intend to enroll in this class, but are not yet enrolled (e.g., on waitlist): 1) Send email to Dr. Dash ([email protected]) indicating your intention to enroll in the class. Include your name and IU email address. 2) Continue to attend class and participate as if you are already enrolled. Stellar Birth: Adrift 1,500 light-years away in one of the most recognizable constellations, the glowing Orion Nebula and the dark Horsehead Nebula. The former is a great example of a stellar nursery. Stellar death: In 1987, the brightest supernova in recent history occurred in the Large Magellanic Cloud, a companion galaxy to the Milky Way. At the center of the picture is an object central to the remains of the violent stellar explosion. Homework #1 will be posted next week. There will be an announcement posted and an email broadcast concerning this homework when it is posted. Class web page: www.astro.indiana.edu/~classweb/a100s26782 Homework assignments, announcements, reading assignments, etc. Consult this site on a regular basis. Long, long, ago, On a hillside far, far, away… Science begins with observation: And now, an exercise in observation “Observed Facts” and Interpretation and analytic thinking… Science begins with observations… You will be shown a sequence of images of successive full Moons (20 cycles, repeated) assembled into a video format. Working with people near you, address the following: Describe how the Moon’s appearance changes from one full moon to the next. What do we see in the sky? (with the unaided “naked” eye) STARS Many points of light “fixed” in relation to each other but changing location in the sky with time SUN Location changes on yearly cycle (typical star) MOON Moves relative to stars and regularly changes position and appearance over a period of a month (satellite of a planet) PLANETS: Five points of light that slowly wander with respect to sta MILKY WAY Cloud-like band through sky (our galaxy) NEBULAE Fuzzy cloud-like objects (clouds of gas, dust) COMETS Extended objects with tails (“dirty snowballs”) METEORS “Falling Stars” (rocky or metallic objects) Some things are visible only with telescopes PLANETARY SATELLITES: “Moons” ASTEROIDS: Rocky or metallic planetesimals GALAXIES: Homes of stars, gas, dust, … “home” Typical Galaxy: roughly 1011 stars Observable Universe: roughly 1011 galaxies How much is 1011? If you counted one number per second, worked an eight hour day, it would take 10,000 years to count to 1011! OR… McDonalds has sold over 1011 hamburgers! Local Group – Few dozen “nearby” galaxies Outside of Local Group, essentially all galaxies moving away from Milky Way with velocity proportional to distance! Direct prediction of uniformly expanding universe BIG BANG – Universe approx. 13 x 109 years old Galaxies don’t like to live alone… CLUSTERS of GALAXIES: few to thousands of gravitationally bound galaxies SUPERCLUSTERS: Clusters of clusters of galaxies What is the Earth’s place in the Universe? A video interlude… “The Cosmic Connection”
