ASTRONOMY

Look to the Sky……Why? Astonomy is a Human Adventure – even if you’ve never looked at the sky! The development of astronomy is intertwined with development of civilization Revolutions in astronomy revolutionize the science and technology that shape modern life It’s really, really cool!

Dead Dudes of Astronomy Pythagoras (500 BC) Greek philosopher Believed that circles and spheres were “perfect” heavenly forms: thus the Earth must be a sphere (since the Earth was “obviously” at the center of the Universe). Perfect “10”

Aristotle Greek Philosopher (300 BC) Described evidence for spherical Earth: Lunar eclipse always showed curved shadow of Earth Altitude of North Star changes as we travel north, suggesting Earth’s surface if curved As a ship sails over the horizon, we lose sight of the hull before the sail.

Ptolemy (140 AD) Created the Geocentric Model of the Earth Earth was center of all motion Everything moved around Earth in circular orbits (Model was accepted as official doctrine of Catholic Church until the Renaissance)

Hypatia (355?-415) Natural Philosopher in Alexandria, Egypt Wrote books on Astronomy, Geometry, and Philosophy Developed ideas on conic sections, leading to ideas of hyperbolas, parabolas, and ellipses Hypatia came to symbolize learning and science which early Christians identified with paganism

Copernicus (1473-1543) Polish doctor, lawyer, and amateur astronomer Sought simpler model Solution: Heliocentric – or sun-centered – model, but the model lacked evidence Published ideas on his deathbed

Galileo (1564-1642) DID NOT invent the telescope, just used it first for astronomy! Discovered moons of Jupiter Observed imperfections on Moon’s surface Discovered that the sun rotates by observing sunspots Convicted of heresy, went blind, died under house arrest. Conviction overturned in 1992!!

Einstein (1879-1955) General Theory of Relativity = “shape” of space is influenced by matter and energy in it, and space is curved Special Theory of Relativity = deals with how light behaves in curved space, and establishes that speed of light is a constant (300,000 km/second)

Carl Sagan (1934-1996) We are all “star stuff” Well known for putting scientific concepts into everyday language for the public

Steven Hawking (1942-Present) *Not so dead dude…… Theoretical Physicist worked on the basic laws which govern the universe showed that Einstein's General Theory of Relativity implied space and time would have a beginning in the Big Bang and an end in black holes Lucasian Professor of Mathmatics, Cambridge University, a possition once held by Isaac Newton

EARTH’S COSMIC ADDRESS Earth is the 3rd Planet from the Sun The sun is one of 100 Billion star systems in the Milky Way The Milky Way is one of 40 galaxies in the Local Group, The Local Group is part of the Local SuperCluster, which is part of the Universe

Galaxies A large group of stars, gas and dust held together by gravity. There are three main types of galaxies. Lenticular Elliptical Spiral **There are at least 80 billion galaxies in the Universe!!!

Lenticular Galaxy Spiral without spiral structure:

Elliptical Galaxy Ellipsoidal shape – looks like a cosmic football! Contain little or no interstellar matter

Spiral Galaxy Large flat disc with spiral arms and a bulge:

The Milky Way Spiral Galaxy Our Sun is one of several billion stars in the Milky Way.

Features of a Spiral Galaxy Disc – made up of mainly younger stars that are 1 million to 10 billion years old Bulge – at the core, high density, tend to contain very old (>10 billion years) red stars Halo – surrounds the disc, made up of low density old stars and dark matter

Our Sun is in the Orian Arm of the Milky Way 2/3 of the way from center of the Milky Way

Closest Neighbor Andromeda Galaxy – much like Milky Way 2.2 million light years away and approaching us at 670,000 miles an hour!