Astronomy

Galaxy

clsusters of a few million to 400 billion stars

• ex: Milky Way galaxy

• small galaxies may orbit larger ones

• three shapes

  • spiral galaxies: flattened disks with spiral or barred spiral arms

  • elliptical galaxies: spherical in shape with no spiral arms

  • irregular galaxies: no distinct shape

Universe

enormous collection of matter

solar system

planets, moons, etc circling a star

Planets

Mercury: terrestrial

Venus: terrestrial

Earth: terrestrial

Mars: terrestrial

Jupiter: gas

Saturn: gas

Uranus: ice

Neptune: ice

Wave

a repeating disturbance that transfers energy through matter or space

• ex: ocean waves, sound waves, seismic waves, light waves

frequency (waves)

number of waves per unit of time

Parts of a Wave

Crest: highest point on a wave

through: lowest point on a wave

amplitude: distance between where the wave begins and where it ends

wavelength: the distance between two waves

Newton’s findings regarding light

• 1666

• studies light traveling through a prism & saw a spectrum of colors: ROYGBIV

Hugenns’ findings regarding light

• 1670s

• determined light travels in waves; shorter wavelengths are refracted (bent) more than longer wavelenghts

• this discovery led to the creation of spectroscopy

spectroscopy

• the study of the properties of light

• radiation (light) released or reflected by distant objects allows scientists to study the universe

electromagnetic spectrum

• the continuum of radiation released by celestial objects

Electromagnetic waves

• travel at the speed of light-300,000 km/s

• transfer energy

• travel through space

types of electromagnetic radiation

• Gamma (CT scans)

• X-Rays

• UV light = sunburns

• infrared = heat

• microwaves & radio ______

Speed of light

• speed of light (c) - relationship between frequency and wavelength

• 3 × 10^8 meters/sec (186,000 miles per sec!)

c = f(λ)

• speed of light (m/s) = frequency (Hz) x wavelength (m)

• this equation can be used to find wavelength or frequency of different types of light when we know the speed of light

• traveling at the speed of light you could circle the Earth 7 times in less than a second

What is energy measured in? What are the two formulas to solve it?

Electron Volts (eV)

1. E=hf

2. E=hc/λ (Iambda)

h = Planck’s Constant = 6.626 × 10³4 Joules (J)/second

f = frequency

c = speed of light

λ = wavelength

The Big Bang Theory

• Theory that the universe began as a singularity and has been expanding ever since

  • occured about 14 (13.7) billion years ago

• singularity - zone of infinite density

what does this mean?

• all matter squished into a tiny amount of space

Expansion of the Universe

Universe has two opposing forces:

1. Momentum of outward exxpansion

2. gravity pushing inward to slow expansion

What would the possible outcomes of the universe be if a certain force became too strong?

• depends on which opposing force is stronger

• three possible possibilities:

1. Open

• expansion will never stop

2. closed

• expansion stops and begins to contract

3. flat

• expansion slows to a halt, but does not contract

Contents of the Universe

• universe expansion is accelerating (dark energy)

• composition

  • dark energy (75%) (unknown)

  • dark matter (21%) (unknown subatomic particles)

  • luminous matter (4%)

What is Hubble’s Law?

42 miles/second : 3 million light-years

Einstein’s Theory of Relativity & Quantum Physics

• math based theory that proves objects are moving away from a “singularity” (and relative to each other)

Cosmic background radiation

• weak radiation left over from the early, hot stages of the Big Bang expansion

Cosmic Background Radiation

• Discovered in 1965 

   (background noise in radio antenna)

• Shorter wavelengths of light (when hot) that became longer (when cooled) 

• The “leftovers” of the Big Bang

What is the relationship between wavelength and frequency?

Bigger wavelength = less frequency

smaller wavelength = more frequency

Doppler Effect

an apparent change in the frequency of waves when the observer or the source of the waves is moving relative to each other.

Measuring Doppler Shift

• When an object in space is moving, its spectral lines will be shifted towards one end of the spectrum. 

• We can use this shift to determine how fast a star is moving.

Describe Blueshift and Redshift

When objects are moving away from us, they show a red shift. When objects are moving towards us, they show a blue shift.

Interstellar Cloud/Nebula

clump of dust clouds mostly containing hydrogen and helium

Collapsing of Cloud (Contraction)

1. gravity (perhaps a nearby supernova explosion?) draws the matter together causing the cloud to collapse

2. collapsed cloud spins faster pushing dense material to the center (will become SUN)

3. When temps reach 15 billion degrees C, nuclear fusion begins →the Sun is born!

4. When spin slows the cloud will become a flat rotating disk