space

galaxy

galaxy

gases, dust, billions of stars held together by gravity

nebula vs galaxy

nebula is where stars are born vs galaxy is a large collection of stars

shapes of galaxies

spiral, elliptical, irregular

galaxy characteristics

all spinning and contain large numbers of stars

differ in size mass, brightness, colour, speed of spin

more spin means flatter galaxy

globular clusters

stars held together by gravity in spherical shape

open clusters

have less stars than globular clusters

nebula

large cloud of gas and dust

protostar

earliest stage of a star’s life

a star is born

• all stars start as nebulas

• gravity can pull some of gas and dust in a nebula together

• contracting cloud then called a protostar

• a star is born when the gas and dust from a nebula become so hot that nuclear fusion starts

• when a star has “turned on: it is known as a main sequence star

• when a main sequence star begins to run out of hydrogen fuel, it turns into a red giant or red super giant

star birth order

nebula, protostar, main sequence star, red giant/red super giant

death of medium mass star

• after becoming a red giant, the outer parts grow bigger and drift into space, forming a cloud of gas called a planetary nebula

• bluewhite hot core of sun that is left cools and becomes a white dwarf

• white dwarf eventually runs out of fuel and dies as a black dwarf

death of a high mass star

• dying red super giant star can suddenly explode

• after explosion, some materials from star are left behind

• they may form a neutron star

• the most massive stars become black holes when they die

• after a large mass star explodes, a large amount of mass may remain

• the gravity of the mass is s strong that gas is pulled inwards, pulling more gas into a smaller and smaller space

• eventually gravity becomes so strong that nothing can escape, not even light

supernova

sudden explosion of dying red super giant star

neutron star

remains of high mass stars

past beliefs to now

• for centuries people believed there was only earth and sky

• 26 centuries ago, anaximander figured out that there’s space on all sides

• other ancient greeks concluded that the earth was a sphere, with celestial objects orbiting it

• copernicus figured out that the earth orbited the sun

• then figured out our solar system was one of a hundred billion in our galaxy

• then that our galaxy is one of a hundred billion galaxies

gravitational singularity

one dimensional point which contains a huge mass in an infinitely small space, a point of infinity, laws of physics as we know do not operate at this point

doppler effect

• apparent change in the frequency of a wave caused by relative motion between the source of the wave and the observer

• the thing that is emitting waves moves

• in front, it bunches up, behind the thing, it spreads out

• when it’s moving towards a stationary object, these bunched up waves are observed at a high frequency, moving away - waves observed at a low frequency

blue/red shifts

• blue shift - star moving towards earth, wavelengths of light have been compressed, spectral lines shifted towards blue end, higher frequency

• red shift - star moving away from earth, wavelengths of light become longer, spectral lines shifting towards red end, lower frequency

elemental fingerprints

• each element gives off unique spectral signature/fingerprint

• can analyze light coming from different objects in space and determine their composition by comparing fingerprints

• different elements emit different wavelengths of light

emission spectrum

• spectrum consisting of several narrow, bright, bands of light

spectroscopy

technique of splitting light (electromagnetic radiation) into its wavelengths (a spectrum) in the same way as a prism splits light into a colour of rainbows

electromagnetic radiation

energy that is carried or radiated in the form of rays (microwaves, radio waves)

spectrum

band of rainbow colours created when white light passes through the prism

each colour of spectrum represents different wavelength of light

edwin hubble

• american astronomer

• discovered all galaxies were moving away form each other

  • galaxies further away from our galaxy (milky way) were moving away from each other faster than galaxies that are closer to ours

  • galaxies twice as far away were moving twice as fast as closer galaxies

  • suggested that all galaxies must have had a common point of origin

  • discovered this through spectroscopy

  • spectral lines were all shifted towards the red part of the spectrum -indicates that galaxy is moving away from observer on earth

    • occurs because light’s wavelengths are getting longer

    • called cosmological red shift - red has longest wave length

    • main evidence for big bang theory

big bang theory evidence

• cosmological red shift

• cosmic background radiation is evident

  • leftover radiation from initial explosive expansion of the universe, echo of big bang

  • predicted by astronomers

• mapping of background radiation (satellite COBE in 1989)

• mapping of microwave radiation (by spacecraft WMAP in 2001)

• expansion implies that universe was smaller in the past

big bang theory (summary)

• universe began with gigantic expansion13.8~ billion years ago

  • not explosion - they fly outward into empty space that there was prior to the explosion

  • with the big bang, there was no space for it to expand into

• nothing existed before this - no space, no time

• out of nothingness came the universe and it started to expand

• universe was too hot right after the explosion for subatomic particles to form

  • subatomic particles present (protons, electrons, quarks, etc) but they were moving so fast due to the heat they didn’t form atoms

• as universe cooled, particles slowed down and combined with each other to for hydrogen atoms (380 000 years after the Big Bang)

• so hot that first hydrogen atoms gave off radiation that can still be measured today (CMB - cosmic background radiation)

• as universe continued to cool down, the hydrogen atoms could condense and form stars

• condensation/cooling allowed for all other bodies in the universe to form

big bang + right after

• at the moment of the big bang, the entire universe existed as an infinitely small, dense, and hot point - singularity

  • contained everything we see in universe today

  • not explosion, but rapid expansion (cosmic inflation)

• moments after big bang, period of rapid exponential expansion of the universe

  • lasted fraction of second - universe expanded faster than speed of light

  • after this period it began to expand at a more gradual pace at which it’s still moving today

timeline

• big bang

• inflation

• after 380 000 years, electrons cool enough to combine with protons, universe transparent to light

• dark ages - clouds of dark hydrogen gas cool and coalesce

• first stars - gas clouds collapse, fusion of stars begins

• galaxy formation - gravity causes galaxies to form, merge, and drift

  • dark energy accelerates expansion of universe at slower rate than inflation

• dark ages - hot - billions of degrees

  • dense - crammed together tightly, bursting at seams

  • fast - infinitely small to size of softball in less than a billion of a second

  • dark - crammed so tightly light couldn’t get out

  • plasma - hot soup of charged particles

what did the big bang create

space, time, energy, matter

matter/energy relationship

• shortly after big bang, matter and energy were indistinguishable, but less than a second later, they separated into two separate things

• prior to einstein, astronomers understood universe according to newton’s laws of motion (1686)

• e=mc² shows energy and mass are interchangeable - different forms of same thing, (matter can be converted into energy and vice versa)

  • mass is concentrated energy and has lots of energy in it

  • energy was turned into matter after big bang

  • mass increases with speed

  • near speed of light, mass is so high it reaches ∞, would require infinite energy to move it, capping how fast object can move

  • light moves at the speed because photons(quantum particles that make up light) have a mass of 0

how did energy change over time

• transferred by forces - push/pull

• after big bang, energy split into 4 fundamental forces of nature within a fraction of a second

• these laws govern the universe today (gravity, weak nuclear force, strong nuclear force, electromagnetism

gravity

first force to emerge, force of attraction between all matter - pull only, weakest force, infinite distances

strong nuclear force

second force to emerge, holds nucleus together, basically attractive, can repel (mostly pull can push), strongest forces, short distances

electromagnetism

third force to emerge, push (repulsion of like charges) and pull (attraction of opp charges), acts between matter carrying an electrical charge, infinite distances, second most powerful

weak nuclear force

fourth force to emerge, stronger than gravity, extremely small distances, cause tiny particles of matter to change identity, causing radioactive decay, push

matter

anything that has mass and volume

building blocks - what give matter form

1. electrons/quarks

2. protons/neutrons

3. atomic nuclei

4. plasma

5. atoms

electrons and quarks

moments after origin of universe, quarks have partial charges - up quarks and down quarks

protons and neutrons

• quarks combined into groups of large particles - neutrons

• 2 up quarks and 1 down quark created proton, opposite created neutron

atomic nuclei

protons and neutrons then bound together - by strong nuclear force

plasma

for next 380 000 years, universe consisted of mostly uniform plasma of charged particles - positive atomic nuclei, negatively charged electrons

atoms

• universe cooled enough to form first atoms

• electromagnetic force caused positively charged electrons to become attracted to negatively charged electrons

• electrons began to swirl around nuclei and first neutral atoms came into existence

• first atom was hydrogen, second was helium

  • light atoms were first, hydrogen and helium first and second most abundant

  • 73% of mass of visible universe is hydrogen, 25 is helium, everything else was created after big bang within stars and represents 2%

solar system basic info

• sun is centre, heliocentric

• solar system full of planets, moons, asteroids, and comets

  • all revolve around the sun at the centre

• when a star forms from a nebula, gravity pulls most of the material into the new star, some may also clump together to form objects in a solar system

• ormed 4.5+ billion years ago

planet

celestial body that orbits one or more stars, may spin on axis as it orbits the sun

planet requirements

celestial body must orbit one or more stars, be large enough that its own gravity holds it in a spherical shape, and be the only body occupying the orbital path

planet order

sun, mercury, venus, earth, mars, jupiter, saturn, uranus, neptune

inner rocky planets and outer, gaseous/jovian planets

• after the sun formed, material closest to the sun developed into inner/terrestrial planets

  • small, solid cores, rocky crusts

  • mercury, venus, earth, mars

• material further from the sun developed into the outer/Jovian planets

  • large gaseous bands, cold temperatures

  • jupiter, saturn, uranus, neptune

astronomical units

how distance between planets in the solar system is measured

1 au - sun to earth

mars - 1.5 au, jupiter - 5.27 au, neptune - 30.06 au

rotation

• motion of earth as it spins on its axis from west to east

• spins on axis at 1670km/hr (one full rotation takes almost a day)

revolution

• motion of earth as it orbits usn

• orbits sun at 30km/sec - one full revolution takes almost a year

sun

• contains more than 99% of mass in solar system

• composed of mainly hydrogen gas

• nuclear reactions in the sun’s core causes hydrogen to form helium

• energy is radiated to earth, keeping it warm enough to support life

solar wind

• sometimes gases from sun erupt outwards like bursting soap bubble

• resulting solar wind is full of high energy particles that would kill any life on earth they struck

• our magnetic field deflects this solar wind

  • see the deflection when we see the northern lights

asteroid

• small leftover remains from the formation of the solar system

  • 1000s of asteroids orbit in asteroid belt between mars and jupiter

comet

composed of ice, rock, and gas (dirty snowballs)

• leaves trail of gas and dust when in contact with sunlight

• rocky travelers - following orbits far outside planets in the oort cloud

other solar system bodies

• bodies smaller than planets in our solar system

• moons found around all planets except mercury and venus

oort cloud

at farthest reach of the sun’s gravitational pull, almost 25% of way to next nearest star, proxima centauri

trans-neptunian o bjects

• beyond neptune

• compoesd of fragments of material left over from formation of the solar system

• these objects orbit the sun in a larger area known as the kuiper belt

• pluto is a dwarf planet

plutoid

dwarf planets past neptune

dwarf planets

orbit sun, have enough gravity to pull itself into spherical shape

pluto

• demoted at the 26th general assembly of international astronomical union in prague (2006)

• only argument for keeping it was “tradition” - no scientific justification for calling pluto a planet

• pluto in kuiper belt, where nearly all are chunks of ice and rock like pluto, we just discovered pluto first

• pluto isn’t even biggest , eries - 25% bigger by mass than pluto

• haumea, makemake, ceres

• up to 100 big things in kuiper belt

• downgrade because so many big planets - planet would stop being useful as a term

• new criteria : orbit sun, have enough gravity to pull itself into spherical shape, clear everything out of mass

  • only 0.07 times mass of everything in orbit vs earth is 1.7mil times

kuiper belt

asteroid belt past neptune, has trillions of things in it

geocentric model of celestial motion

earth considered centre of universe, everything revolved (moon, mercury, venus, sun, mars, jupiter, saturn) earth, based on ptolemy (greek astronomer)’s work

our understanding

• humans aware of relationships between earth, sun, moon for 1000s of years, but only recently begun to better understand the true nature of the relationships

• ancient civilizations used the seasons, months, positions of stars and other astronomical information in many parts of their lives

• used to believe geocentric

• polish astronomer copernicus was first to suggest heliocentric model

  • created contreversy → galileo, italian physicist and astronomer was put on trial for suggesting earth was not centre of universe

• with time, heliocentric model was accepted

• with kepler (german mathematician and astronomer)s work, accurate predictions of planets’ orbits became possible, further strengthening the validity of this model

moon’s formation - giant impact theory

• orgin of moon believed to have resulted during earth’s early formation

• planetary body the size of mars slammed into a young earth

• impact is thought to have been so large, parts of both planets broke off and scattered into space

• impact sped up earth’s rotation and tilted orbital plane 23 deg

• earth reformed as large molten body

• fragments ended up orbiting earth and eventually built up to form the moon

moon surface

• no atmosphere on moon to protect from bombardment from debris from space

• results in moon’s surface being covered by many large circular craters, ancient lava flows, high mountains

moon phases

• moon produces no light -

• moonlight is sun’s light reflected from the moon’s surface

• moonlight takes one second to travel to earth

• sunlight takes eight minutes

• as moon is orbiting earth, sun lights it from different angles

• these different angles are called phases

• moon takes 29.5 days to revolve earth

• rotates at the same rate it revolves, so we always see the same side of the moon

• new moon, waxing crescent, first quarter, waxing gibbous, full, waning crescent, last quarter, waning gibbous,

full moon phase

when the Sun is lighting up the entire portion of the Moon visible from Earth

new moon phase

when the Sun is lighting up the side of the Moon not visible from Earthwhen the sunlit portion of the Moon increases in size from night to night and it is said to be waning when the sunlit part of the Moon is decreasing

waxing

when the sunlit portion of the Moon increases in size from night to night

waning

when the sunlit part of the Moon is decreasing

lunar gravity

• as moon orbits earth, lunar gravity attracts the water in the ocean causing high and low tides

• lunar gravity causes tides

• effect of centrifugal force on ocean, result of earth orbiting around centre of grav between it and universe

earth’s rotation + tilt

• day and night caused by earths spin on its axis from west to east

  • takes 23hrs 56 minutes, 4sec

• axis is tilted 23.5° from flat plane of earths orbit

• 

• axis tilt means suns light strikes earth at different angles during earths annual orbit around the sun (seasons)

• tilt towards the sun in northern hemisphere - summer in northern hemisphere

• tilt away from Sun in northern hemisphere - winter in northern hemisphere

• equator - imaginary line around middle of earth, hit by suns rays directly all year

• June 21 - longest day of year (20-22 - summer solstice)

• Dec 21 - shortest day of the year (20-22 - winter solstice

• sept 22-23 - autumnal equinox

• march 20-21 - vernal equinox

• in far northern latitudes, axis tilt is extreme so Sun does not set below horizon in summer; does not rise in winter

eclipse

total or partial overshadowing of one celestial body by another

lunar eclipse

• when earth lies directly between moon and sun during a full moon phase and earths shadow is cast on the moon, causing moon to be briefly blacked out, may become red like smog/sunset illuimated with light scattered by earths atmosphere

solar eclipse

• when moon is between sun and earth and moon blocks the suns light and the shadow of the moon falls across portions of the earth

• (Moons orbit tilts about 5° from the plane of earths orbit so solar eclipses don’t occur once a month)

• during a solar eclipse, people living where the umbra touches earth witness a total solar eclipse

• people living where the penumbra occurs witness a partial eclipse

constellations

• distinctive patterns in night sky formed by groups of stars

• Polaris - North Star, tells direction

meteoroids

pieces of rock, broken off from asteroids or planets; floating through space

meteors

meteoroids that burn up as they pass through earths atmosphere

meteorites

meteoroids that are too large to entirely burn up in earths atmosphere and so reach earths surface

asteroids

• rocks that are orbiting sun

• 480 miles to less than a mile in diameter