questions from last test Flashcards
What is one source of light pollution?
Cities, street lights, the moon, nothern lights etc
Why can light pollution cause problems for astronomers?
Because their pupils are dilated and they cannot see the stars. affects night vision
What is a fireball?
A very bright meteor
Describe the appearence of aurorae
Light (often green) spiralling downwards
What is aurorae?
Charged particles from solar wind interacting with gas molecules in the atmosphere.
How do scientists use sunspots to determine the suns’s rotation period?
sunspots appear at certain points on the sun. Scientists track where they are to work out the rotational period.
Describe the appearance of sun spots with a H-alpha filter
They have a dork centre with a slightly lighter ring surrounding it.
Why would an astronomer use a H-alpha filter?
shows contrast
What are two pieces of evidence used to show extreme global warming on Venus?
- Very thick/dense atmosphere traps heat
- Lots of Carbon dioxide
Which month of the year do shadow sticks give the shortest shadows at noon in the UK?
June
Which members of the solar system was the first to be discovered by using a photograph?
Pluto
Which members of the solar system was the first to be discovered by using a telescope?
Uranus
where to centaurs orbit the sun?
Jupiter and Neptune
I which part of the sky would an observer expect to observe a planet?
the Zodiacal Band
What does the angle of elevation of polaris above the horizon equal to?
The viewers latitude
What is a globular cluster?
A large group of old stars.
What can help you observe with your naked eyes?
A red torch or a relaxed eye.
What are 2 sources which can help you prepare for an observation?
Weather report, Planisphere
What is an open cluster?
A large group of young stars
meridian
imaginary line that runs from north to south through the zenith
why may an astronomer not be able to observe a certain constellation?
Due to the earths orbit of the sun. it may be in line with the sun or behind the earth making it not visible.
One major space mission:
Apollo, first humans on the moon, The moon is lifeless + contains very very old rock.
Galaxies in our local group:
Milky way, pisces dwarf, Aquarius Dwarf
how do we tell an active galaxy?
strong x-rays and radio emitters
How do astronomers observe neutron stars?
radio telescopes. Recieve radio waves in regualr bursts/pulses
What is a pulsar?
A pulsar is a rotating neutron star that emits a beam of electromagnetic radiation.
What are PHO’s?
thing that come relatively close to earth for example Comets, meteors and asteroids.
Why are PHO’s regarded as hazardous?
because they could hit earth and cause devastation.
What is meant by: alpha, beta, gamme, delta etc?
Order of stars relative brightness
At what distance is apparent magnitude equal to absolute magnitude?
10pc
What is parallax?
looking at a star in june and then the same star in december means the star appears to move slightly, relative to the distant stars behind it, because we’re looking at it from a different angle. this effect is called parallax and can be used to work out the distance to the star with d = 1/ tan theta
the theory that the moon was formed when a large body crashed into earth is backed up by:
similar isotopic abundances (oxygen) and lack of water and KREEP rich rocks.
What is Keplers second law/
An orbiting body will cover similar areas in the same time.
what might an X-ray astronomer observe?
black holes, pulsars.
How were quasars discovered?
They are very strong radio sources furthermore highly reshifted emission line detected very distant galaxies. This fitted an optical observation of faint star like objects.
What is the messier catalogue?
show what nebulae are visible and location of nearby galaxies.
how was CMB radiation discovered?
investigation of radio noise from all parts of the sky at day and night.
What is the cosmological significance of CMB radiation?
evidence of the big bang (cooling universe)
What is the significance of ripples in the CMB?
may show distribution of dark matter/galaxies in the early universe.
How can the Hubble constant be used to estimate the age of the universe?
Convert the Hubble constant to an ‘inverse time’. If the graph was steep then the Universe would be young. The less steep it is the older the Universe: t = d / v
Describe the appearance of an open cluster E.g. the pleiades
fuzzy appearance. quite faint with a few visible stars.
What was the next year after 1976 which solar maximum occurred?
1981
why are there more lunar eclipses that solar eclipses?
Because the earth is bigger and will cast a bigger shadow than the moon (more likely for the earth to block out the sun than the moon)
Describe the naked eye appearance of the milky way
Strip/band across the sky with fuzzy lights/stars
Explain how measurements using long exposure photographs of circumpolar stars can be used to determine the rotation period of the Earth.
Stars appear the circle around polaris (when being photoed using long exposure) and complete the circle after 24hrs. so every hour the complete 15 degrees of the rotation. we can work out the rotation period by seeing when the star makes the full circle.
How do astronomers experimentally test the possible water origin coming from comets?
They land space probes on comets and sample matter to compare it to elements on earth
obaf…
…gkm
Why is the dust tail curved?
because particles spread out
What are the specific purposes of two instruments in the ALSEP?
To study moonquakes
testing for an atmosphere
What is the giant impact hypothesis?
Early in the formation of the solar system a large body of rock, about the size of Mars, crashed into earth and the debris went into orbit and collected together to form the moon: backed up by similar isotopic abundances on the moon and earth.
What is Oscillating?
The universe will undergo a period of expanding then shrinking (Many big bangs and big crunches)
What is dark matter?
Matter that does not give off any detectable radiation but has gravitational effects.
What is dark energy?
Energy proposed to explain why the expansion of the Universe might be accelerating.
Hubble constant
The Hubble Constant is the unit of measurement used to describe the expansion of the universe.
Steady state
The theory that the Universe is expanding, but new matter is constantly being created, so that the overall density of the Universe remains constant.
How do astronomers detect black holes?
x-rays
how do you know the maria are made out of younger rock?
less craters
How are wrinkle ridges different to rille?
wrinkle ridges are longer and wider
what did galileo discover?
Venuses phases + Jupiter moons
Who discovered the inverse square law?
netwon
where is dust + young stars found?
spiral arms
What is a Parsec?
The distance to a star which has a parallax angle of 1 arc second
What are three methods used to find new planets?
transit method- seeing if light levels drop is a planet transits its star
the radial velocity method- use Doppler shifting to see if a planets gravity affects the star
the astrometry method- measuring a stars position very precisely then measuring its wobbles due to a planets gravity
What does the ecliptic show?
The motion of the sun
What can be obtained from studying the spectrum of a star?
size, temperature, chemical composition.
What is the purpose of WMAP (CMB radiation)?
to study ripples/variation in more detail.
Why was WMAP (SCB radiation) observations important?
shows that CMB is leftover radiation from the big bang and allows astronomers to estimate proportion of dark matter/ dark energy.
What are neptunes moons?
Kuiper belt objects
how do we know the earth is not flat?
sattelites/images from space + you see ships disappear over the horizon
When a star is due south of an observer What measure of its position reaches maximum?
elevation
Culmilation
A celestial body to reach the meridain/ highest point
A collection of meteoroids from a dust tail of a comet?
Meteor stream
Why do the biggest telescopes use mirrors?
no chromatic aberration
what does out atmosphere absorb?
UV, IR, X-ray, Gamma rays
What is the latitude of sunspots during solar maximum?
+- 20
Soltice
longest or shortest day of the year
Equinox
length of day and night are equal
What is the SETI project
to search for intelligent life
We know black holes exist becasue of…
orbitting stars
supernova remenent…
dust and gas left after a star explosion
What is the scale which impact hazards are measured?
torino
What is the Cepheid Variables?
Cepheid Variables are very large, luminous, yellow stars. They change in brightness very regularly
What is a Cosmic ray?
Cosmic rays are energetic, subatomic particles that arrive from outside the Earth’s atmosphere. The lowest energy cosmic rays are produced by ordinary stars like the Sun. For example, during a solar flare many particles are ejected from the Sun.
What is Cosmology?
the origin and evolution of the universe
What is Aperture?
a space through which light passes in an optical or photographic instrument
What is Apogee?
the point in the orbit of the moon or a satellite at which it is furthest from the earth.
Accretion
Where dust and gas accumulate into stars or planets
What is Perigee?
the point in the orbit of the moon or a satellite at which it is closest to the earth the earth.
What is perihelion?
the point in the orbit of a planet, asteroid, or comet at which it is closest to the sun.
What two gases absorb large amounts of infra-red radiation?
water vapour, methane, Carbon dioxide
How do astronomers work out the distance to a Cepheid variable star?
determine the time period and use period-luminosity equation to obtain M. rearrange M= m+5-5log(d) to calculate d
What is a primary eclipse?
when the smaller of the binary stars is infront
How can you safely observe the transit of venus??
Look at the sun through solar filters or pinhole projecters
What is the y axis of the hertz-sprung russel diagram?
Luminosity
How was ceres discovered?
piazzi - with a large reflecting telescope while searching the zodiac
How was Pluto discovered?
tombaugh - it was shown in repeated photos
What is greatest elongation?
when a planet appears the furthest from the sun it can be, e.g. the sun is on the east horizon and the planet is on the west horizon.
What are the van allen radiation belts?
Regions of radiation that encircle the earth. One effect is trapping charged particles which can damage satellites.The radiation belts are a result of the Earth’s magnetic field, and contain mostly protons.
What is it called when one object blocks another from view? (passes in front of it.)
Occulation
Inclination
Inclination is a measure of how the plane of an orbit is tilted with respect to the plane of the ecliptic.
ionsphere
the layer of the earth’s atmosphere which contains a high concentration of ions and free electrons and is able to reflect radio waves.
heliosphere
the region surrounding the Sun and the solar system that is filled with the solar magnetic field and the protons and electrons of the solar wind.
Rotation period of earth =
angle of arc
