Class web page
Transcript Class web page
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:
Red Cross: www.redcross.org
Doctors Without Borders: doctorswithoutborders.org
Save the Children:
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
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:
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
And now, an exercise in observation
Facts” and Interpretation
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
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)
Many points of light “fixed” in relation to each
other but changing location in the sky with time
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)
Fuzzy cloud-like objects (clouds of gas, dust)
Extended objects with tails (“dirty snowballs”)
“Falling Stars” (rocky or metallic objects)
Some things are visible only
PLANETARY SATELLITES: “Moons”
ASTEROIDS: Rocky or metallic planetesimals
GALAXIES: Homes of stars, gas, dust, …
Typical Galaxy: roughly 1011 stars
Observable Universe: roughly 1011
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!
McDonalds has sold over 1011
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
BIG BANG – Universe approx. 13 x 109 years
Galaxies don’t like to live alone…
CLUSTERS of GALAXIES: few to thousands of
gravitationally bound galaxies
SUPERCLUSTERS: Clusters of clusters of
What is the Earth’s place in the Universe?
A video interlude…
“The Cosmic Connection”