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115 Cards in this Set
- Front
- Back
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How many planets in solar system |
8 |
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How many stars in our galaxy and what is our galaxy called |
200 billion, milky way |
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how many light years does it take to travel width of our galaxy |
100,000 light years |
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What is the furthest manmade object called?How far is it? |
voyager 1, it is 150AU close to the edge of solar system |
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what does CCU stand for and what is its scaling factor? |
captain cook unit, 1 AU = 1 CCU = 500m |
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what is AU? |
the distance between earth and sun, something we use to measure large distances. it is 149 million km |
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what is the AU to CCU scaling factor? |
1CCU/1AU |
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how do you using the scaling factor to better understand the size of something? |
you multiply the original size by scaling factor |
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where is AU measuring helpful? |
between planets |
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What is measuring in light years used for? |
distances between stars |
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What is the closest star to our sun and how far away is it |
proxima centauri, 4.2 light years |
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what is one light year |
the distance light travels in one year, 9.5x10^12km |
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What is a parsec? |
it is a measurement of distance,1pc = 3.26 light years |
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what is the classical age of universe |
15 billion years |
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How long ago did the first humans emerge |
130,000 |
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when did life on earth begin |
3.5 billion years ago |
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How old is the sun/solar system |
sun is around 4.5 billion years old |
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when will the sun die |
in around 7 million years |
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when were the first star maps as cave paintings dated to? |
15-17000 years ago |
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What is a celestial sphere |
what early astronomers pictured the universe as. the earth in the centre with a celestial sphere covered in stars that move around it around the pole lines |
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celestial poles |
fixed axis in which the earth rotates |
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how many degrees is the ecliptic plane rotated leading to seasons/ equinoxes |
23.5 degrees, the seasons occur when sun rays hit the earth at different angles throughout the year |
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what planets did the ancients know about? |
mercury, venus, mars, jupiter and saturn (Make very messy jelly sauce) they stay 8 degrees of ecliptic plane |
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what is the ecliptic plane |
plane of the sun and earth orbit |
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constellation definition |
group of stars seen from earth that resemble outline of animal object or mythological creature |
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what is equinox |
two times in year when night and day are same length |
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what is a tropical year |
sun returns to the same place in the sky as seen from earth (also called a solar year) 265.242 days. we use it so seasons dont get messed up |
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what is a sidereal year |
time it takes for earth to complete one orbit around the sun based on measurements of the stars 265.256 |
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what is procession |
the axis in which the earth rotates is slowly chnaging direction, caused by gravitational pull from moon and sun, hence the pole star is not fixed. a complete rotation takes 25800 years |
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How do planets move |
west to east, sometimes go through retrograde which is when the earth overtakes them as they have different paths around sun |
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naked eye observations of the ancients: |
diurnal rotation, 5 planets, tropical/sidereal year, lunar phases, procession of equinoxes, eclipses of sun and moon |
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what is celestial equator |
projection of earths equator up onto celestial sphere |
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what is solstice |
longest and shortest periods of daytime |
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ancient definition of planets |
stars which are not fixed to celestial sphere |
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astrological zodiac |
12 constellations within 8 degrees of ecliptic |
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What is the ancient importance of astronomy(3) |
1. time keeping and calendars 2. agriculture 3. religion |
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What is astronomy |
science dedicated to the study of everything outside earths atsmosphere |
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cosmology |
study of universe as a whole |
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astrology |
unfounded superstition |
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how old is astrology and where did it start |
3000BC, mesapotania |
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who was claudius ptolemy |
150AD codified astrology from omen to horiscopes based largely off information from mesapotamia and ancient greeks |
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who said that astrology was absurd |
carneades |
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what is some skeptisim of astrology |
the constellations arent fixed, new planets have been discovered, procession of equinoxes arent taken into account |
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what is matariki |
maori new year |
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helical rising |
when star rises just before dawn around the same direction as rising sun |
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What did the sumerians develop |
60 counting system, 360 degrees, 360 day year, 30 day months, extra month added when needed |
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what did the babylonians develop |
in 500BC they changed to a 354 day lunar calendar, some months 30 days others were 29, had to add 7 extra months over 19 years, introduced 7 day week, made predictions of patterns of eclipses etc but didnt know why they occur |
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what did the egyptians develop |
decimal counting system, diurnal motion of stars for 24 hour day, solar calendar 360+5 days, astronomical observations were used to align pyrimids |
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what could ancient maori naked eye astronomers see |
jupiters moons |
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what did polynesians use astronomy for |
navigation, stars gave latitude. |
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who is thales of miletus |
624-547BC, father of physics made observations of stars |
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who is Parmenides of Elea |
520-450BC, credited the earthw as round and that the moon was illuminated by the sun |
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how did Anaxagoras of Clazomenae describe the shape of the earth |
said it was drum shaped (cylindrical) |
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what 4 peices of evidence did aristotle use to try prove the earth was a large round sphere |
1. on hill can see slight curve 2. eclipses 3. long journeys you can see stars emerge over horizon 4. elephants found in india and morocco |
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Who recorded the first measurement of earths radius |
Etrasthenes (276-195BC) using angle of sun between syen and Alexandria. he calculated the radius of the earth was 6366km (modern values are 6378) |
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How does christopher columbus relate to erosthenes? |
he believed the measurement was wrong and much smaller as the stade was not a good measuring unit, this messed up a few of his voyages |
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what is a geocentric universe and who did it emerge from |
the idea that the earth lay still at centre of solar system and that everything else moved around it in celestial sphere. idea came about from pythagorous plato and aristotle (who did consider the earth may be in motion but concluded otherwise) |
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what is triganometric parralax |
introduced by aristotle, it is the apparent movement of close object against background of very distant object when the observer moves. . the closer an object the larger the parrallax |
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what is the parrallax for the closest stars |
less than 1 arc second 3x10-4 degrees |
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how long did the geocentric universe remain fixed |
2000 years |
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how far can parrallax measure |
100 ly from earth and 300 ly from sattelites |
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How to measure distance of stars |
need to use parrallax taking a picture of a star 6 months apart (2AU in distance) and compare againts background of much furtehr stars |
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What is the parrallax equation |
D= 3.26ly/p (p = arc seconds) |
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What is a parsec |
short for parrallex second, one parsec is the distance to a star such that its parralax is measured to be one second of arc p=1'' which is 3.26 lightyears |
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what caused issues with the celestial sphere |
the planets: they vary in brightness, they wonder around the celestial sphere not fixed like stars, they undergo retrograde motion |
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what model of the solar system did astronomers create to try to incorporate the retrograde motion of planets |
wheels within wheels: planets travel around a small circle (epicycle) and the centre of this circle moved around a larger circle (the deferent) that encased the earth. this couldnt reproduce observations however, especially with mars. next came claudius ptolemy in 150AD who created the equant to geocentric model, it did well for predictions and lasted 13 centuries however 80 different circles were used |
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What is the heliocentric universe |
a model of the solar system in which the sun lay at the centre, originally from Aristarchos of Samos 300BC |
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what happened to the model of the solar system during the renaissance |
nicolas copernicus (1473-1542) used mathematics and observations to conclude the sun was at centre of solar system. Didnt go down well with church. his model explains both retrograde and varying brightness of planets. this model didnt work any better than ptolemaic model at making predictions |
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who was Tycho Brache and johannes Kepler |
unconvinced of the heliocentric solar system, wanted to test copernican model. Brache was very good at collecting expiremental data and johannes was good at maths |
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what are keplers laws |
1.each planet moves in an eliptical path with the sun at focus 2. a line joining the sun and planet sweeps out equal areas in equal times 3. the square of the planets orbital period is proportional to the cube of its semi-major axis |
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What does the solar system ACTUALLY look like |
the sun lies at the focus of an eliptical orbit, not in the centre of a circle |
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When was the telescope first unveiled |
1608 |
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Who was Gallileo Gallilei and what did he do |
Florentine scientist was leading telescopic design between 1609 and 1611. he was first to see: mountains and valleys on moon, planets are disks stars are points, discovered moons of jupiter 1610, phases of venus, possibly saw rings of saturn |
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who was isaac newton |
from he precessors work he created the 3 laws of motion and discovered universal gravity |
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How was universal gravity discovered |
isaac newton showed that the gravitational force on a planet varied with raidus of the planets orbit, created law of universal gravity. small deviations from purely eliptical paths of planets were caused by gravitational attraction amongst the planets themsleves |
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How can telescopes help us see stars |
they make them brighter by their light gathering capability measured by their diameter the resolution of a telescope helps make out details (large telescopes have better resolving power) |
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What are two colours of light that stars emit |
blue (shortest wavelength, best resolving power) & green (the middle of visible light spectrum) |
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what is the limiting factor in telescope resolution |
diffraction - bending of light. proportional to wavelength divided by the diameter of the telescope mirror |
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Radio telescopes |
scan the sky for radio waves rather than light, much longer than visible light so need to be big to get good resolution |
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what is the diffraction limited resolution of the keck telescope |
1 hundredth of an arc second |
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How was the AU measured |
using radar, we measured the distance from venus when it was closest to earth and when it was furthest giving 2AU |
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What did captain cook do |
observed the transit of venus |
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atmospheric turbulence meaning |
causes diffraction of light entering our atmosphere so stars are fuzzy, only around 1-2 seconds of arc wide seeing disc |
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What is Hipparcos |
a telescope launched into space in 1989 that can make measurements accurate to 0.001 arc-seconds that allows measurable distances out to 3260 ly (30kpc) 3% of the diameter of our galaxy |
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who is hipparchus of Rhodes(190-120BC) |
devised a scale for apparent brightness of stars using naked eye(5000): 1st magnitude are the brightest stars an 6th magnitude are the faintest, scaling factor being 2.512 for each magnitude, the 1st magnitude are 100 times brighter than 6th |
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what is the modern view on stars magnitudes |
since we can measure them now, some stars lay outside of the 6 magnitudes so the brightest ones can go into the negatives |
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what is the apparent brightest star in the sky using naked eye and what is its magnitude |
sirius - m=-1.5 |
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apparent brightness vs luminosity |
luminosity is an intrinsic property of star, it doesnt depend on the location or motion of star however more luminous means higher apparent brightness dependent on distance |
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What does the brightness of a star measured from earth (measured by its apparent magnitude m) depend on |
its luminosity (absolute brightness and its distance from the earth |
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what is the absolute magnitude |
the apparent magnitude a star would have if it were moved 10 parsecs away from earth to better understand a stars brightness in contrast to other stars |
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why are some stars more luminous |
because they are different sizes and temperatures. |
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are blue or red stars hotter |
blue |
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what is 0 Kelvin in celcius |
-273 |
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what is the colour procession as an object gets hotter |
dull red, red, orange, yellow, white, blue/white |
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How are stars temperatures measured |
pointing a telescope that only allows light to enter over a range of specific wavelengths |
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how hot is the surface of our sun |
6000K |
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What is luminosity |
intrinsic property of star. it is the total power (measured in watts) over all wavelengths radiated by a star that does not depend on distance from observer. migger surface area radiates more |
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what kind of light rays do astronomers tend to use |
ultraviolet (angular resolution more like 0.1 seconds of arc) |
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how do you measure radius of far away stars |
luminosity^(1/2)/temp^2 |
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what is the suns luminosity |
1 |
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What happened to Giordano Bruno |
stated that the world was infinate and that the sun was one of many stars, he was burned at the stake |
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What did Renes descartes believe |
pushed that universe was filled with matter not a vacuum |
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what did Christian hyugen do |
compared brightness of our sun to sirius |
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what did Freidrich Willhelm bessel do |
used parrallax to determine distance to far away star proving how big the universe is |
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what did Freidrich angelo succhi discover |
using spectroscopic techniques realised the chemical makeup was the same in our sun as distant stars, proving its a star |
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What did Joseph von Fraunhofer measure |
the wavelengths of dark lines between visible light through a prescision prism |
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what are the dark lines seen when looking through a spectrometer at a gas |
absorption lines when the specific gas was cool |
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what are the bright lines seen when looking through a spectrometer at a gas |
emission lines for a specific gas when it was hot |
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how do you get absorption lines |
shine light on gas , the elctrons interact with light at certain wavelengths |
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how do you get emmission lines |
heat up gas, excited electrons give off light at certain wavelengths |
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what is spectroscopy |
the identification of chemistry and properties of matter |
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what is the gas like at the centre of the sun |
hot and dense |
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what are absorption lines useful for |
measuring the absorption lines of stars to get their surface temperatures |
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what are the strength of absorption lines of stars dependent of |
the temperature of the gasses |
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What is the classification based off surface temperature of stars |
O,B,AF,G,K,M with O being hottest at 30,000K and each following letter being cooler |
