What I got wrong in past papers Flashcards
What does orion’s belt point to?
Sirius
What is meant by the local group?
Galaxies close to us
What is the diagonal band in the Hertzsprung - Russell Diagram known as?
Main sequence
Where are white dwarfs in the Hertzsprung Russell diagram?
Top right
Where are red giants in the Hertzsprung Russell diagram?
Bottom left
How do astronomers observe neutron stars?
Neutron stars emit radio waves in bursts/pulses
They use radio telescopes to observe these
Where is the proposed origin of long period comets?
The Oort Cloud
At what distance is the apparent magnitude of a star equal to its absolute magnitude?
10pc
What is supposedly younger, Terrae or Maria?
Maria
Why are the world’s largest telescopes reflectors rather than refractors?
Mirrors let more light in meaning higher resolution
What’s an astronomical object that an X-ray astronomer might observe?
Sun’s Corona
State two key facts about Quasars:
High redshifts and AGN at the centre
How were Quasars discovered?
Lunar occulation
Strong radio sources
Highly redshifted absorption lines
What information can you obtain from the Messier Catalogue?
Which nebulae/clusters are visible
Location of nebulae
How was CMB radiation discovered?
Radio noise
Radiation measured from all directions
What is the significance of the ‘ripples’ in CMB radiation?
Distribution of matter/galaxies
Evidence for dark matter/energy
Which was the first member of our solar system to be discovered using photographs?
Pluto
Describe the appearance of an open cluster:
Fuzzy, faint, few bright stars visible
Why can lunar eclipses be observed more often than solar eclipses?
Because the Earth is bigger than the moon in relativity to the sun so more of the Earth can see the lunar eclipse
How does solar wind cause aurorae?
charged particles react with atoms in the atmosphere which emits fluorescence light
Why is the dust tail of a comet slightly curved?
dust particles spread out due to independent orbits
What absorbs IR radiation in the atmosphere
Carbon Dioxide
How were the van allen belts discovered?
discovered by geiger counter
Describe the doppler principle:
change in wavelength due to relative motion between source and observer
What are circumpolar stars?
Stars that don’t set
What is averted vision?
Not looking directly at an object; observing slightly to the side
What does the two most right stars of the plough point to?
Polaris
What type of star lies at the centre of a planetary nebula?
White dwarf
What do astronomers use to detect black holes?
Microwaves
What is the approx diameter of the Milky Way?
30kpc
Why is it not possible to map the spiral arms using visible light?
Dust absorbs visible light
Why is it important to monitor the motion of PHOs?
To predict if an impact is likely
What is the significance of white patches on the sun?
Strong x-ray emitters, very high temperature, site of solar flare
Why does h-alpha improve observations of the sun?
Shows the atmosphere
Why would radio communication be a major problem on a space mission to mars?
Large distances - time delays
What is the physical nature of Saturns rings?
Not solid, thin
What is the chemical composition of Saturns rings?
Rock/ice
Frozen gases
How was CMB discovered?
In 1965 by penzias and Wilson using horn antenna
What was the specific purpose of WMAP?
To study ripples or variations in CMB radiation
What is the significance of WMAP’s observations to cosmologists?
Refine models of early universe
Estimate the proportions of dark matter/energy
How do astronomers use the spectrum of a star to classify its spectral type?
Astronomers compare the relative strength of H, He and metals
Relative amounts relate to O,B,A etc
What is the significance of the ecliptic on a star chart?
Shows motion/path of the sun
