ASTRONOMY
ASTRONOMY
is the scientific study of extraterrestrial objects and phenomenons.
COSMOLOGY
is the study of the origin, structure & future of the universe.
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THE EARLY ASTRONOMERS
In the year 140, Ptolemy theorized that Earth was the center of the universe, and that the other planets and the sun revolved around the Earth.
In 1543, Copernicus theorized that the sun was the center of the universe and that the Earth revolved around the sun along with the other planets.
Also in 1609, Kepler stated that the planets revolve around the sun in elliptical orbits.
Kepler also theorized his laws of planetary motion that are still used today.
In 1609, Galileo used the telescope to observe objects in space including craters and mountains on the moon and sunspots on the sun.
In 1687, Newton showed that all objects attract each other due to gravity, explaining why one object orbits another.
In 1924, Hubble proved that other galaxies existed beyond the Milky Way, and that the universe is much larger than our own galaxy.
http://www.youtube.com/watch?v=GmwAr54L_pM&feature=related
THE ELECTROMAGNETIC SPECTRUM
The wave length reflects the type of energy, from long wavelength radio waves to very short wavelength gamma waves. Light waves are the only part of the EM spectrum that we can see.
All energy travels in waves.
http://www.youtube.com/watch?v=bjOGNVH3D4Y&feature=related
Different types of telescopes can detect different wavelengths to construct images, from visible light
to radio to x-ray images.
MEASURING DISTANCES IN SPACE
* Light Year - the distance light travels in one year, equal to 6 trillion miles or 9.46 trillion kilometers. We measure distances outside of our solar system in light years.
* Astronomical Unit - the distance from Earth to the sun. We use AU's to measure distances
within our solar system.
Study of the origin, structure
& future of the universe
All objects attract each other due
to gravity Shows
wavelengths of different types
of energy Copernicus,
in 1609 Gamma
waves
Radio waves Distance from
the sun to the Earth longest diameter
of the orbital ellipse 8.3 minutes
Orbiting objects move along elliptical paths
other galaxies exist beyond
our own Ptolemy,
in 140 C.E.
study of extraterrestrial
objects &
phenomenons.
Galileo, in 1609 6 trillion miles -
distance light
travels in 1 year
STARS
Star color indicates the surface temperature. Red has a longer wave length than blue & so is cooler. Stars are classified by their temperature.
Star composition consists of elemental plasma. Because different elements absorb various wavelengths
of light, a star's composition can be determined with a spectrograph.
THE LIFE OF STARS
The type of star depends on its mass during formation.
Average mass stars become main sequence stars .
The higher the mass of a star, the shorter its life because it burns through its fuel quickly. Smaller mass stars have much longer lives.
Stars are created within nebulas, called "star nurseries"
HERTZSPRUNG-RUSSELL DIAGRAM
The "H-R" diagram graphs a star's absolute magnitude against its surface temperature
THE DEATH OF STARS
Supernovae are tremendous explosions of giant stars in which the outer layers are blown away.
Neutron stars form after the supernova of a high mass star and is twice the mass of our sun. All the particles inside the star’s core collapse under gravity and are forced together to form neutrons.
A spinning neutron star is called a pulsar and can be identified using radio telescopes.
Black holes form from the super nova of a super massive star, with gravity so intense that not even light can escape. They
can be identified using x-ray telescopes.
GALAXIES
Spiral galaxies have a central bulge and spiral arms composed of gas, dust and young stars.
Elliptical galaxies are massive groups of older stars with almost no gas or dust.
Irregular galaxies have no specific shape.
http://www.spacetelescope.org/videos/html/mpeg/320px/heic0912a.html
STAR CLUSTERS are groups of stars . . .
Globular clusters are groups of older stars that can form halos around galaxies.
Open clusters are smaller groups of new bright blue stars found outside galaxies along the spiral plane.
NEBULAS are large clouds of gas and dust, usually left over from supernovas, that act as star nurseries.
QUASARS are the most distant star-like objects and the oldest & most powerful energy sources in the
universe. They may be massive black holes in galactic centers.
The BIG BANG was the theorized
explosion that created the universe, and where all energy, matter and space began.
Astronomers calculate the time of the Big Bang by measuring the distances between galaxies and the speeds they are traveling apart.
The Big Bang is estimated to have occurred between 10 and 15 bya.
When the universe was . . .
. . . one trillionth of a trillionth of a
billionth of a second old, it was the size of a grapefruit and 100 boC.
. . . one second old, the universe had cooled to 10 boC. 1,000 times hotter than the sun and too hot for atoms to exist. The universe consisted of plasma of radiant energy, electrons & neutrinos. Then protons and neutrons began to form...
. . . 1.5 minutes old, the universe had cooled to 1 boC. Atomic nuclei began to form but it was still too hot for
atoms.
For the next million years, the universe continued to expand and cool, atoms began to form when the temperature dropped to a few thousand degrees.
Evidence of the Big Bang includes . . .
* Background Radiation - radiation energy left over from the initial explosion permeates the entire universe.
* Red Shift - similar to the Doppler Effect, red shift on the EM spectrum indicates that objects
are moving away.
At the time of the Big Bang there was no matter in the universe, only pure energy.
Within the first second of the Big Bang the 4 Universal Forces appeared . . .
* Gravity - the attraction of 1 body toward another, and the weakest of the forces
* Electromagnetic force - binds atoms into molecules and is why electrons repel each other;
emits a wide range of wavelengths from gamma to radio waves
* Weak Nuclear force - causes the radioactive decay of atomic nuclei
* Strong Nuclear force - binds protons and neutrons together in the atomic nucleus
Our universe has been expanding since its formation by the Big Bang around 14 billion years ago.
It was recently discovered that the rate
of universal expansion is accelerating.
FORMATION OF OUR SOLAR SYSTEM OUR SOLAR SYSTEM formed within a nebula, the remnants of a supernova.
Over billions of years, the spinning eddy created gravity that pulled particles together.
The particles collided forming larger and larger bodies.
Planetesimals became planets.
The centermost region where gravity was greatest
became incredibly dense, creating tremendous
pressure that formed the sun, our very own star.
THE SUN
THE SUN: OUR VERY OWN STAR
Our sun contains 99% of our solar system's mass.
The sun's energy is created by nuclear fusion, mainly of hydrogen
to helium.
THE SUN'S STRUCTURE
Sunspots are the dark areas of the photosphere that are cooler than the surrounding areas.
Sunspot activity follows an 11 year cycle, and is thought to be involved with Earth's climate.
The movement of energy from the sun's interior causes the photosphere to boil and churn.
This circulation plus the rotation of the sun creates the sun's enormous magnetic field.
Solar flares are also caused by the sun's magnetic field. Solar flares are regions of extremely high temperature and
brightness that erupt huge streams of electrically charged particles thousands of kilometers into space.
hold protons together in nucleus sun spots
nuclear fusion a nebula
corona
core
15,000,000C 2 objects attract
hydrogen
to helium photosphere deuterium
radiative zone holds atoms
into molecules solar flares
chromosphere planetesimals
comb. of electricity &
magnetism 11 years convective
zone accelerating 99%
Semimajor axis
Major axis
PLANETARY MOTION
Rotation is the spinning of a body on its axis.
Revolution is the orbit of one body around another.
Orbit is the path one body follows around another.
KEPLER'S 1st LAW OF MOTION
All orbiting bodies move in elliptical paths.
KEPLER'S 2nd LAW OF MOTION
Planets move faster when they are closer to the sun and faster when they are farther away.
KEPLER'S 3rd LAW OF MOTION
A planet’s distance from the sun can be
calculated by knowing its period of revolution.
Inertia
