astronomy general science spring ‘07. history of the universe earth = 1 of 9 planets sun= 1 of 100...
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AstronomyAstronomy
General Science Spring ‘07
History of the UniverseHistory of the Universe
Earth = 1 of 9 planetsSun= 1 of 100 billion stars in the Milky
Way, 1 of infinite numbers in our universe
Ancient AstronomyAncient Astronomy
Golden Age= 600 BC-150 AD in GreeceBeliefs relied on philosophy (ideas) and
observations.
Geocentric ViewGeocentric View
At first, we thought the Earth was the center of the universe
Geo=Earth -centric=center
Heliocentric viewHeliocentric view
Eventually, we realized the SUN was the center of our galaxy.
This was called the HELIOcentric view.
Modern AstronomyModern Astronomy
Ideas based more on observation
Nicholas Copernicus (1473-1543, Poland)– Earth rotates– Said Earth is a planet
(only 5 known at this point: Mercury, Venus, Mars, Jupiter, Saturn)
Johannes Kepler (1571-1630)Johannes Kepler (1571-1630)
Laws of Planetary Motion– The path of each planet
is an ellipse– Each planet travels at
its own speed– Astronomical Unit
(AU) = 150 million kilometers
Galileo Galilei (1564-1642)Galileo Galilei (1564-1642)
Around at the same time as Kepler
Favored the heliocentric viewpoint
Created the telescope (which later made him go blind
after looking at the sun through it) Discovered the four
moons of Jupiter
Sir Isaac Newton (1643-1727, Sir Isaac Newton (1643-1727, England)England)
Law of Gravity! Proved Kepler’s idea
that planets orbit in an ellipse.
Trip through our UniverseTrip through our Universe
Light year= how far light
travels in one year Speed of light= 186,000
miles per second!
Billions and billions of stars
Carl Sagan 11/9/34-10/20/96
ConstellationsConstellations
Star groups that form patterns as seen from Earth
Big dipper (ursa major)Little dipper (ursa minor)Orion
NovasNovas
When a star suddenly increases in brightness (100x) in a few hrs/days, then dims back to original state.
Gases from one binary star strike the other causing nuclear explosions which we see as light.
NovasNovas
NebulaeNebulae
We see light from stars, but most give off other types of radiation– X-Rays, Infared (heat), UV light, radio waves
All types can be seen by different types of telescopes.
NebulaeNebulae
A huge massive cloud glowing between stars.
Where new stars form
GalaxiesGalaxies
Contain stars and are major features of our universe.
There are billions of galaxies each with billions of stars of their own.
Three Types of GalaxiesThree Types of Galaxies
Spiral– Shaped like pinwheels– Andromeda– Milky Way
Three Types of GalaxiesThree Types of Galaxies
Elliptical– Vary in shape from
spherical to flat discs– Contain little dust/gas
Three types of GalaxiesThree types of Galaxies
Irregular– No ordinary shape– Least common
The Milky WayThe Milky Way
100,000 light years across!
15,000 light years thick!
It would take, traveling at the speed of light, 100,000 years to cross!
Earth and its MoonEarth and its Moon
Magnetic field- invisible lines of force that connect poles
Earth has a magnetic core
Made from iron and nickel
Earth= MagnetEarth= Magnet
Van Allen Belts– Doughnut shaped
fields that trap particles from solar wind (e- and p+), produce auroras
– Can see the aurora borealis in Canada and Alaska
Neil Armstrong + Buzz AldrinNeil Armstrong + Buzz Aldrin
First men to land on the moon
July 20,1969 Neil Armstrong first to
step on the moon
First Step on MoonFirst Step on Moon
The Moon’s MeasurementsThe Moon’s Measurements
3476 km in diameter Gravity 1/6 that of Earth 384,403 km from Earth 4.6 billion years old No H2O, no atmosphere 100oC @ noon, -175oC at
night
The Moon’s FeaturesThe Moon’s Features
Galileo was the first to observe the moon
Saw mountains and low areas.
Saw craters formed by asteroids
The Moon’s movementThe Moon’s movement
Moon revolves around EarthPerigee- closest to Earth (350,000 km)Apogee- furthest (400,00 km)27.5 days to rotate on axis27.5 days to revolve around the Earth
– Why we only see one side of the moon.
The Moon’s OriginThe Moon’s Origin
Several TheoriesAsteroid “captured” by Earth’s gravityFormed from the same nebulae as the
planetsAsteroid (size of Mars) struck Earth, ejected
chunk of Earth outward (widely accepted theory)
Nothing 100% certain
Earth, Moon and Sun Earth, Moon and Sun
The reflection of the sun on the moon results in changing appearance of moon as seen from Earth.
The Moon appears to change shapeThe Moon doesn’t shine, it reflects light.
Phases of the MoonPhases of the Moon