THE UNIVERSE Flashcards
chicken itzà
their pyramids were made to align with significant astronomical events
stone henge
- it was created with the purpose of evidencing astronomical events
- the design of this structure is said to be the axial alignment and serve as a caledonia
pyramids of gyza
it was built so the corners of the pyramids align with the cardinal directions. there are similarities between the position of the pyramids and the stars of onions belt
ancient greece
philosophers were able to define astronomy by making an observational science become more theoretical
shapes of stars and planets
perfect shape
plato
- there are two worlds
- tangible and intangible (platos cave)
- the immaterial world represents the perfect aspects
- the objects and ideas in out material word are shadows of the forms
geocentric model
- the earth is the center
- was developed through observation
heliocentric
- the sun is the center of the solar system
johannesburg kepler
- discovered that the earth and planets travel around the sun in elliptical orbits
- the planet to sun distance is constantly changing
- as the planet goes around the orbit, planets move proportionally faster in their orbits when they are closer to the sun
telescopes
- they are an instrument that help us learn about out universe
- the bigger the telescope is, the better, since it can collect more light and create sharper images
aperture
the larger the diameter, the more light it will collect
resolution
the ability to separate 2 objects emitting radiation
refractor telescope
- they were the first telescopes ever created
- they have a curved lense at one end that focuses the light down a long tube towards a second lense, called the eye piece which magnifies the image
reflecting telescope
- they were first developed by newton
- they use mirrors to collect and focus light towards the eyepiece
- mirrors are lighter than lenses and also easier to shape into a smooth surface
infra red telescope
- picks up infra red radiation
- can be located out of space or on high mountain tops
- detects nebulae, gas and dust
x ray telescopes
- pick up on x ray radiation
- can only be located out of space since the atmosphere reflects x ray radiation
- it detects shock waves of explored stars
gamma telescopes
- picks up on gamma rays
- can only be located outside of earth since the atmosphere blocks most gamma radiation
- it detects exploding stars and black holes
radio telescopes
-picks up on radio waves
- it consists of a radio receiver, and antena system and an amplifier
- it is located on land on a really high altitude
- it detects galaxies
james webb telescope
- infra red telescope
- biggest and most expensive telescope created
- consists of a golden mirror, and a sun shield to keep it cool
cosmological constant
- einstein thought that everything was always contracting, so the universe that was made out of matter would collapse
- he proposed a cosmological constant repulsed the gravitational force
- this theory was not proved
big bang
- used to explain why the universe is expanding
- it is caused by the repercussions of the explosion
- gravity is not slowing down the expansion
E=mc^2
- space and time are interchangeable
- mass-energy tell space-time how to curve
- space-time tell mass-energy how to move
gravity
deformation in space-time
theory of relativity
set of theories developed by einstein to describe the laws of physics that govern the behavior of objects in motion
classical relativity
there is no absolute motion or rest
special relativity
- the laws of relativity do not change for objects in motion
- speed of light is always constant
time dilatation
-it states that the speed of light is constant and unchanging for all observers, so time passes more slowly for objects that are moving close to the speed of light, relative to objects at rest
- m/s= 1m/1s == m/s = 3m/3s
length contraction
- it states that object appear to be shorter in the direction of their motion, when viewed by an observer moving relative to them
- the effect of length contraction is related to time dialtation and and it is a direct results of the consistency of the speed of light
- objects move faster, is relative velocity to the speed of light increases, causing the object to to appear shorter in the direction of this motion
general relativity
-gravity is not a force, but rather a result of curvature of spacetime caused by the presence of massive objects
- massive objects cause space time to curve,and this curvature in turn added to the motion of other objects
steady state model
it states that the universe has always existed in a state of balance, with matter being continuously created to maintain for same average density
big bang model
- it is the current accepted theory regarding the origin of the universe
- the universe began as a singularity, an infinitely small and dense point around 13.8Bya
- after the bang of the universe, it rapidly expanded and cooled, leading to the formation of hydrogen and helium and the eventual formation of the stars
- the discovery of cosmic background radiation is one of the biggest evidences
- the radiation is the remains of the initial explosion and is the reason the universe expanding (Penzias and Wilson OBE AND WMAP)
- the abundance of light elements such as hydrogen and helium are thought to have been produced shortly after the explosion, reason why they are so common in the universe
olbers paradox
- the night sky is dark, contradicting that if the universe is filled with invite stars emitting light
- red shifting: one solution to the paradox states that the stars have redshifted, meaning that an object is moving away from us appears to be shifted towards longer red wavelengths, making the invisible
10^8
the purest number un science, it is the number of atoms in the visible universe
galaxy
- is a huge collection of gas dust and billions of stars and their solar system
- it is held together by gravity
- galaxies can come in different shapes which are determined by their speed
stars
- luminous balls made up of a hot glowing gas (hydrogen and helium
- they are held together by their own gravity
nuclear fussion
- occurs in the core of the star to light it up
- in the core there is a higher temperature and pressure, where hydrogen atoms are combined to form helium, releasing energy in the form of light
- the death of a star will happen when there is no more helium to convert
formation of stars
- clouds of gas and dust called nebulae
- a dense region of nebulae collapses under its own gravity
- it heats up and becoming denser, reaching temperatures high enough to ignite nuclear fusion in its core which releases enough energy for a star to be born
russel diagram
used to classify stars based on their luminosity and temperature in relativity to the sun
red dwarfs
- small, doll stars, that are smaller than out own sun
- they are the most common type of star in the galaxy
white dwarfs
- small, dense and extremely hot stars that are remnants of low mass stars
- emit uv radiation
red giants
- evolved stars that have used up hydrogen fiel in their cores are now fusing into helium and heavier elements
- much larger and brighter than sequence stars
hyper giants
- they are the largest and most luminous stars in the universe
- be aside of their mass they tend to live shorter as more energy, gravity, and nuclear fusion are needed
supernova
- powerful and luminous explosion that occurs when a star runs out of nuclear fuel
- the explosion is one of the most energetic events in out universe
- these explosions are the source of heavier elements
- because of the massive energy and high mass, it is likely for them to form black holes
solar system
consists of stars, sun, and everything bound to it by gravity
kuiper belt
lies past neptunes orbit, and is a sparsely occupied ring of icy bodies
oort cloud
- giant spherical shell surrounding the rest of the solar system
- it has never been observed directly, but its presence has been predicted through mathematical models
formation of solar system
- 4.5Bya from a dense cloud of interstellar gas and dust
- this cloud collapse due to the shockwave of a supernova, forming a solar nebula
- at the center, gravity pulled more and more material in, building enough pressure to form the star
- matter started clumping together, forming plants and moons
- the order was determined by the order of formation, making the outer regions younger
- they are also organized by te amount of water they contained
gravitational lenses
- natures magnifying glass
- galaxy clustered are the biggest magnifiers known because of their huge gravity
- it works when a light beam is bent because of an object with massive gravity, making the object appear bigger
LIGO
- designed to detect gravitational waves (ripples in the fabric of space time)
- it has two lasers in an L shape that are in a vacuum to reduce interferences
- the laser beams are reflected back and forth by mirrors at the end of the arms, and when they recombine they interfere with eachother, revealing changes in the arm lengths caused by gravitational waves
