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48 Cards in this Set
- Front
- Back
- 3rd side (hint)
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E.1.1 Outline the structure of the solar system
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the eight planets orbiting the sun are collectively known as the solar system
each planet is kept in elliptical orbit by the gravitational attraction between the sun and the planet |
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what are dwarf planets?
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smaller planets such as pluto and platenoids
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Mercury
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distance km:
distance to sun |
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Venus
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distance in km
distance to sun |
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Earth
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distance in km: 12756
distance to sun: 149.6 |
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Mars
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distance in km: 6787
distance to sun: |
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what is an asteriod
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a small rocky body that drifts around the solar system.
there are many the sub between mars and jupiter - this is called the asteriod belt |
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what is a meteroid
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it's an asteriod on collision course with another planet
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what are shooting stars
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small meteroids (meteors) vaporized due to friction in the atmosphere
bigger ones lands on the planet and are called meteroities |
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E.1.2 distinguish between a stellar cluster and a constellation
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constellations are a group of stars that form a recognizeable pattern
stellar cluster are stars that are close to each other |
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What is a light year
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the distance travelled by light in one year (9.5 x 10^15 m)
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define astromonical unit
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distance from the sun to the earth is one astronomical unit = 1.5 x 10^11 m.
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define the parsec
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a star of a parallaxel angle of exactly one seconf of arc must be 3.08 x 10^16 m
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What is the Milky Way
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is the band of light we see in the sky at night,. this is some of the million of stars that make up our galaxy
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What is the main energy of stars
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it's fusion of hydrogen into helium
the reaction is a nucleaur reaction |
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Why is the sun stable
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because there is an equilibrium between the outward pressure and the unward gravitational force
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define luminosity
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the total power radiated by a star
the SI unit is Watt |
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define apparent brightness of a star
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this is the power recieved by an observer on earth
the SI unit it Watt m^-2 |
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if two stars are the same distance from the earth, which one would be brighter?
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the one with the greater luminosity
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the brightness is inversely proportional to the distance
brightness b = L/4pi^2 |
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How is the spectrum of a star
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it's not a perfect contineous spectrum as particular wavelength are missing
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Oh be a fine girl, kiss me
O 50,000-28,000 blue B 28,00-9900 blue-white A 9900-7400 white F 7400 - 6000 yellow white G 6000 - 4900 yello K 4900 - 3500 orange M 3500 - 2000 orange-red |
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Define spectral class
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different stars give out different spectra of light and are classified in classes
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define apparent magnitude and absolute magnitude
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apparent: how bright a star appears by an observer on earth
absolute: how bright a star would appear if we were 10 pc from earth |
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State Stefan-Botlzman law and Wien's law
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Wien's: wavelengthmaxT= constant
we can analyse light from a star and calculate its surface temp |
Stefan: this links the power radiated by a black body per unit area to the temperature of the black body
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Define Red giant stars
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these stars a large and red in color
the red color = they're cool fusion taking place of some elements other than hydrogen |
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What is a White darf stars
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small and white in color
white = hot no fusion takes place |
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What are Cepheid variables
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unstable stars
quite rare regular variation in brightness and luminosity |
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Binary stars
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two or more stars that orbit around eah other
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types of binary stars
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visual binary
spectroscopic eclipsing |
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Visual binary stars
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one that can be distinguished to be two different by telescope
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Spectroscopic binary stars
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they can be identified by analysis of the spectrum of the light of the stars
they show a shift in frequency |
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Eclipsing binary star
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identified by analysing the brightness of the star
over time the brightness shows a periodic variation because one star get in front of the other |
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blue-shift and red-shift
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when are star is moving toward the earth its spectrum will be blue-shifted
when it's moving away, its spectrum will be red-shifted |
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Define parallex
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the effect of near objects seeming to move when compared to far objects
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can be use to measure the distance to some stars in the universe
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what is the difference between magnitude 1 star and magnitude 6 star
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the smaller the magnitude the brighter the star
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magnitude 1 star is 100 times brighter than magnitude 6 star
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what is the magnitude scale
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it's used to compare the brightness of stars
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apparent magnitude scale: the brightness of a star depends on its luminosity and its distance away from earth
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state the relation between absolute magnitude, M, apparent magnitude, m and distance away, d
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m - M = 5log (d/10)
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what is spectroscopic parallax
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- doesn't involve parallex
- it's used to determine the luminosity of a star from its spectrum |
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what are the assumptions made using spectroscopic parallax
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- the spectra from distant stars are the same as the spectra of nearby stars
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once luminosity is determined, the distance can be calculated,
b = L/4pid^2 |
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state the uncernities involved^
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- dust between star and observer can affect the light recieved
- it would absorb some light and make the apparent birghtness less than it is |
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the usefulness of a cepheid variable star
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when observing another galaxy, all the stars are approx the same distance away so we need a star of known luminosity which we can use to compae with the other stars.
his is the cepheid variable star |
it's outer layer undergo a periodic compression and contraction and this produces a periodic variation in its luminosity
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Newton's model of the universe
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- it's infinite
- it's uniform - static |
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Olber's paradox
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1) (If there was an infinite number of stars, why is the sky dark?) There is a finite number of stars and each star has a finite lifetime.
2) The universe has a finite age and stars that are beyond the event horizon have not yet had time for their light to reach Earth. 3) The radiation received is redshifted and so contains less energy. |
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explain the universe expanding
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if a galaxy is moving away from the earth, it should be red-shifted. almost all galazy shows red-shift, which means the universe is expanding
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the big bang
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the universe expanding suggests that all galaxy was at the same place at some point in the past.
the expansions was an expansion of space itself and not galaxies expanding into a void |
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What is an open universe
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open universe
- continues expanding infinitevely - force of gravity not strong enough to stop expansion - this would happen if the density of the universe was low |
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Closed universe
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- the expansion would stop and collapse into itself
- would happen if the density was high - force of gravity enough to bring it to an end |
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Flat universe
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- would happen if the density was just
- force of gravity slows down expansion but takes infinite time to come to a stop - possibility of closed and open universe |
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Define critical density
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the density that would cause a flat universe
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5.6 x 10^26 kg m^-3
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