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.