Flashcards
Astronomy test 1
Cards in this deck (116)
- 1What are planetsWanderers of the solar system
- 2What is the increasing scale of the objects in the universegalaxies-stars-planets
- 3what are starsour sun is powered by thermonuclear fusion
- 4what is a nebulaeclouds of glowing gas
birthplaces of stars - 5what are supernovaespectacular detonations at the end of lives of some stars
may lead to pulsars, neutron stars and black holes - 6How many stars are in our milky way?approx 200 billion
- 7what are the different galaxy typesspiral
elliptical
irregular - 8What are the exotic galaxies with powerful sources of radiationActive galactic nuclei
- 9what is cosmologycreation and fate of the universe
- 10how fast is the speed of light300,000 km/sec
- 11what is one light yearmeasure of distance that travelled by light in a vacuum in one year
approx 10 to the 16th
written with a c symbol - 12What is an astronomical unitlength of the semi-major axis of Earth's orbit around sun
approx 8 light minutes for suns light to reach earth
Distance from sun to earth - 13what does star colour depend onrange of wavelengths emitted
i.e. the spectrum - 14what is a parseca unit of distance used in astronomy, equal to about 3.26 light years
- 15what is the parallax methodSimply put, they measure a star's apparent movement against the background of more distant stars as Earth revolves around the sun
- 16what is the radius of the milky way50,000 light years
- 17how long does it take for the earth to rotate on its axis23 hours and 56 minutes
- 18How long does it take for the earth to orbit the sun365 1/4 days
- 19What is the tilt of the earth23 1/2º
- 20What is the ecliptic planea plane in space defined by the earth's orbit around the sun
- 21where do the zodiacs originate fromplanets pass through them at different times during the year
- 22what causes the seasonsdue to axis tilt, as earth orbits the sun is in different parts of the world will get more sun then the other
i.e. NH summer in June
SH summer in December - 23what does perihelion meanclosest point to the sun
- 24what does aphelion meanfarthest point away from the sun
- 25How many constellations are there88 constellation
i.e. Cygnus, Orion, Ursa Major, Southern Cross (Crux) - 26What way do stars rotate around the southern celestial poleclockwise
- 27Why are there latin names for constellations in the southern hemisphereconstellation names are due to the modern explorers
- 28Do constellations vary in different religionsyes
Indigenous Australians form constellations by using stars and the dark parts of the milky way - 29How long does it take for the milky way to turn on its axis150 million years
- 30what is the constellation star brightness defined bybrightness
- 31do constellations change during the year? if yes how early do they riseyes they do due to earth's orbit around the sun
constellations rise 4 minutes earlier than previous night - 32What is one solar daytime interval between one noon and the next
- 33What is a sidereal daytime taken for one rotation of the earth on its axis
- 34what is the difference between a sidereal day and a solar daysidereal = 23 hours and 56 mins
solar day = 24 hours - 35does a solar day change during the yearyes due to the earth's orbit being elliptical
- 36What is a sidereal monthtime taken for moon to return to original spot in the sky = 27.3 days
- 37What is a synodic monththe time between successive new moons = 29.5 days
caused by motion of earth around the sun - 38Why can't stars be seen during the daysun's light scatters atmosphere therefore making it too hard for starlight to penetrate atmosphere during the day
- 39In several billion years, how long will it take for the moon to orbit earth60 days
- 40what is the bright thing around the sun during an eclipse and how hot is itcorona
1,000º K - 41what occurs during a lunar eclipsemoon is lost in shadow of earth
may be full/ partial depending if it passes through umbra or penumbra
can last 1.5 hours
path of moon and earth is inclined 5º therefore moon is either below or above shadow - 42what makes a blood moonearth's atmosphere scatters suns light effectively
when viewing blood moon from moon, earth blocks out sun and around rim of earth there is a reddish glow which is reflected onto the moon, hence BLOOD MOON - 43What happens at solar eclipsesmoon is situated between the earth and the sun
moon shadow is small on the earth, so area of total eclipse (umbra) is small - 44where are the biggest telescopes situatedat high altitudes e.g. chile and the himalayas
- 45who invented the refractorGalileo Gallilei
- 46Who invented the reflectorIsaac Newton
Hence newtonian telescope - 47can light be brought to a focus? by what instrument and in what formyes by a telescope
can be achieved by a lens or a curved mirror - 48what does wave nature of light cause and can it be resolved?Diffraction
instead of point on the telescope, get pattern
makes it difficult to resolve - 49why can resolution be worse than diffraction limitpoor optical quality of telescope
turbulent atmosphere
at good sites, seeing imposes a resolution of about 1 arcsec - 50what has caused people to put telescopes in spaceatmosphere is turbulent and dynamic
not properly focusing - 51what is a reflecting telescopefocus is produced by the objective mirror
- 52What is a cassegrainsecond mirror can be flat but is usually curved to defocus
more complicated to use
celestron and Meade telescopes are cassegrains - 53how can turbulence affect the telescope's imagechanges path of light rays from stars in small amounts
increases size of object
imposes resolution limits of 1 arcsecond - 54How can you track starsalt-azimuth or an equatorial mount
- 55What is an alt-azimuth mountsimplest to set up
adjust both axis (earth rotates on these axis)
ok with 2 computer controlled motors - 56What is an equatorial mountone axis parallel with earth's axis
one motor needed
running at constant speed to track star
tilts telescope to earth's latitude - 57why are the dishes used for radio astronomy so big?radio signals are weak
with many dishes approx 100 m apart, the resolutionary power is stronger - 58How are the northern lights formedsolar particle charges funnel towards the Earth's north and south poles
hit earth's atmospheric gases i.e. H, O2, N
particles excite atmosphere
colours come from different gases - 59What is the bright part of the sun defined byphotosphere is one of the suns outer layers that emits most of the light
site of sunspots
thin layer ~500 km thick - 60What are the other layers of the sunchromosphere and the corona
only visible during eclipses - 61how far can the corona of the sun extend to10 million kms
- 62how far can solar wind extend tofurther than the corona
- 63How big is the suns diameter100 x bigger than the earth's
- 64What is Kepler's third lawsemi-major axis of planetary orbit; a
Roughly, a is the average distance between planet and sun
period P of orbit (time taken for one orbit)
law can be used for anything gravity related - 65What do star colours determinesurface temperature of star
- 66How hot is the surface of the photosphere5800K
- 67what is the difference between kelvin and celciussame as celcius but with an offset of 0
0K = -273ºC
i.e. the suns surface temp is about 5500ºC - 68How much energy does the sun put out every second1000 Joules per second
- 69what is the density of the sun1.4 grams per cubic cm
same density as jupiter or 1.4 times the density of water - 70what is a blackbody theoryone for which we can relate the temp and colour exactly thru simple expressions
- 71What is the red and blue colour associated with in terms of star colourRed is cool planet
Blue is hot planet - 72what is Einsteins special theory of relativityE=mc2
E = Energy
M = Mass
C = Speed of light - 73The Sun's surface is made of granules, how big are they and what is their lifespan?1000 km across
10 min lifespan - 74what are sunspotsdark spots in photosphere. central dark core (umbra) surrounded by a less dark border (penumbra)
- 75Why are sunspots darkthey're cooler
- 76How was it discovered that sunspots movethe Chinese 2000 years ago observed that the sun was rotating and sunspots were seen to move
- 77how long is a solar rotation period4 weeks
depends on solar latitude - 78does the sun rotate at quickly at different latitudesequatorial region spins faster than polar regions
- 79where do sunspots appear mostlatitudes +30 and -30
- 80how strong are sunspot magnetic fields10,000 times stronger than suns magnetic field
- 81what causes sunspotsas the equator moves faster than the poles wrapping of magnetic field process causes polarity of the sun's magnetic field to flip every 11 years
loops of tangled magnetic field rise through the surface - 82what is apparent magnitudehow bright does a star appear to be from earth
- 83what is magnitude 1the brightest star in the sky
- 84What is magnitude 6the dimmest star in the sky
- 85how much brightness results in the difference of 5 magnitudes100
- 86apparent magnitude be defined by using different filters, what are the three filters and how much magnitude do they showU filters = 300 - 400nm (UV)
B filter = 400 - 500nm (Blue light)
V filter = 500 - 600nm (visible, green-red) - 87what is apparent magnitudehow bright stars appear on earth
- 88what is luminositytotal radiation emitted by a star in all directions
- 89what is absolute magnitudeapparent magnitude that a star would have if it were at a standard distance of 10 parsecs
- 90What is a binary star systemtwo stars orbit around a centre of mass
- 91what is Wein's Lawmeasure temperature of a blackbody (star) by colour
is more sophisticated when using a spectroscope - 92what is a spectroscopecontains a prism to split light up into component wavelengths
- 93What element is most predominant in starsHydrogen
75% - 94What is the Harvard classification system for starsOh
Be
A
Fine
Guy
Kiss
Me
Now - 95what is the main sequence for starsa diagonal band across Hertzsprung diagram from hot, bluish, bright stars on the top left to cool, dim, reddish stars in the bottom right
stars have sizes about the same as sun - 96What is a red giantboth bright and cool
have sizes about 10-100 times that of sun - 97what is a super giantrare, bigger and brighter than red giants
e.g. betelgeuse - 98what is a white dwarfhot and dim star
similar size to earth - 99What is a star embryo calledprotostars
shockwaves due to supernovas contract regions of nebulas which give birth to stars - 100how hot is a protostar10 million K
sufficient to start fusion which makes a protostar a star which joins main sequence - 101how long is a stars life10 to the 10 years
- 102what is a H2 regionionised Hydrogen gas in nebulae
- 103What is a H1 regionWhen nebulas have 1 proton and electron
- 104what is the future of the sunlive for another 5 billion years
in 5 billion years the sun will be twice as luminous as present
will swell to 100 times its current diameter
earth destroyed by radiation - 105why are larger mass stars so specialHigher core temperatures
fusion rate strong
hot enough to fuse hydrogen
luminosity is strong - 106how do stars transition to red giantshydrogen in star is exhausted
starved of heat source
gravity wins
no balance between thermal pressure outwards and gravity inwards
core heats up
hydrogen shell burning - 107How can you determine if a star is dead on a globular cluster graphhave moved away from turn off point
- 108How does a star become a Red giantdepends on mass
low-medium stars turn into white dwarfs
high mass stars turn into supernovas - 109What is the evolution of a low-medium mass starhelium burning exhausted at core
core composed of oxygen and carbon contracts
contraction leads to heating of core
core is hotter than usual
helium shell burning around core - 110low-medium mass star continuationstar expands in size
red giant forms
radius is size of earth's orbit
have short lives
unstable
layers cool and become opaque
radiation from inside strips outer layers - 111what does a low-medium mass star formplanetary nebula
- 112how many planetary nebulas are there20,000 - 50,000
short lived phenomenon - 113what is the radius and density of a white dwarfradius of earth
10 to the 6th g/cm3 - 114what are the main star fuelshydrogen
helium
carbon
oxygen
neon
silicon - 115what does a star end up withiron core surrounded by shells of fusing material
iron core contracts under gravity - 116What happens during a supernovainner regions of star fall towards core and bounce off
outward shock waves blow star apart
nuclear density core becomes neutron star
(or core can be destroyed)
black hole forms in extreme cases
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- Tertiary Astronomy Flashcards on Astronomy test 1, created by Olivia Gniadek on 20/08/2018.
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