Astronomy

Starting Big Galaxy – collection of billions of solar systems. Potentially billions of stars in the universe. Order of Size Universe – galaxy – solar system – star -- planet – moon – comet/meteor/asteroid. Powers of 10

Galaxies Galaxies are described by their shape. Spiral – has “arms” that come off of them Elliptical – smooth edges Irregular – does not fit the definitions of the others.

Our Galaxy Milky Way (spiral) – dense center of stars. About 100 lt yrs across Overall size with arms is around 500 lt yrs Light year is the distance light travels in one year. Next closest galaxy is Andromeda 2.2 million lt yrs away

Formation of the Universe Big Bang Theory a. Most scientifically accepted b. About 14.5 billion years ago c. Point of concentrated mass and energy d. Stars are expanding outward like the surface of a balloon. Oscillation Theory a. Series of big bangs and collapses. Steady State Theory a. It is the same now as it always has been

Stars Birth - protostar occurs in a nebulae (a cloud of gases) cloud becomes denser and pulls more gases in due to gravity. Colliding particles create heat, ignition happens and stars are formed.

Life - depends on mass a) small – burns slower, cooler a. red dwarf b. brown dwarf b) medium – burns more quickly, higher temps a. Main Sequence star (our sun) c) large – burns quickly at high temps a. blue super giants

Death – also depends on mass small to medium a. H is gone and star shrinks b. Collapse causes temp to increase and the star to shrink c. Becomes a white dwarf d. Will die quietly just puff out Large H is gone, cools, collapses High heat causes an explosion(nova) Rapidly vibrating neutron star (pulsar) a sugar cube size of a neutron star has as much mass as all of humanity. Very Large Same as above except: Collapse causes super gravity allowing nothing to escape including light c. Black hole

Classifying Stars Star – a body of gas that produces light - Characterized primarily by size(mass) and temperature. - Sub categories come from color and magnitude of brightness. - They produce light from nuclear fusion. - Two hydrogen atoms combine to form a helium atom. H + H  He

Our Solar System Order: Sun Mercury, Venus, Earth, Mars, asteroid belt, Jupiter, Saturn, Uranus, Neptune, Pluto?

Planets All planets: - rotate on an axis - revolve around the sun - have atmosphere - have a core - have an elliptical orbit - named planet from Greek for wanderer

Inner Planets Mercury Venus Earth Mars - Made of rock, called terrestrial - Smaller in size - Closer to each other - Years are shorter, revolution takes less time - Have fewer moons - Have magma inside

Outer Planets Jupiter Saturn Uranus Neptune - made of gases, called gas giants - large - far apart from one another - have rings – made of ice and rock - longer years - were possibly going to be stars but not enough gas to begin fusion PLUTO??????

Earth The apparent motion of the stars and sun is caused by the rotation of Earth. It takes 24 hours for Earth to rotate one time on its axis Earth spins counter clockwise from west to east. So the sun and stars appear to rise in the east and set in the west.

More Earth The earth rotates at 15 degrees per hour. The earth revolves around the sun. It takes 1 year to for one revolution. The path that the earth takes is an orbit and the earth’s orbit is elliptical.

Seasons The Earth is tilted at 23.5 degrees. The combination of the tilt and revolution produce seasons. The earth is actually closest to the sun in January when it is winter and furthest away in June. The seasons depend on whether or not we are tilted toward the sun, not how close we are. June 21st North pole gets 24 hours of daylight. South pole get 0. This is reversed in December

The Moon The moon is a ball of rock The Earth’s only natural satellite. It takes one month to revolve around the earth The moon reflects the light from the sun New Moon – moon is between the earth and the sun, we can’t see it. Full moon the earth is between the moon and the sun we see it completely lit.

Eclipses    Lunar eclipse – when the Earth’s shadow is projected onto the moon Solar eclipse – when the moon passes between the sun and the earth.

Tides The rise and fall of the ocean levels twice a day. Caused by the gravitational pull of the moon

Asteroids, Comets, and Meteoroids Asteroids – rock fragments that orbit the sun Comet – loose mass of rock, dust and gas have a tail produced by the sun’s energy burning the gases Meteoroids – A rock that travels through space not in orbit (shooting star)