an optical double-star
an emission nebula
a dark dust cloud
a supernova remnant

2. What do the Messier objects M32, M49, M58 and M105 have in common?

they are all globular clusters
they were all discovered by Messier on the same night
they are all of magnitude 7.5
they are all elliptical galaxies

3. A cloud of heated hydrogen gas would emit the following:

a continuous spectrum
emission lines
absorption lines
all of the above

4. What are the common applications of a gamma ray telescope?

observation of neutron stars and active galactic nuclei
observation of interstellar medium and hot stars
measurement of planetary magnetic fields
measurement of the large-scale structure of the universe

5. Define the "Tunguska event":

the last "flip" of Earth's magnetic poles, evidence of which is found in core samples of the Tunguska Inlet, Nunavut, Canada
a supernova, bright enough to be observed at daytime for four days, observed in 1873 by Polish astronomer Wassily Tunguska
a vast explosion due to a meteoric impact, which took place in Tunguska, Siberia, in 1908
a sudden, dramatic increase in the intensity of radio emissions of a neutron star, such as Tunguska A in the constellation Tucana

6. What is the observable apparent magnitude limit of Hubble space telescope?

magnitude 18
magnitude 23
magnitude 30
magnitude 42

7. Where do young O and B stars form in the galactic disk?

in the dust lanes
near the galactic bulge
just inside the galactic halo
anywhere on the galactic disk

8. What is a positron?

the positive charge of an atomic nucleus
the result of a proton-proton chain
an atom consisting of a proton and a neutron
a positively charged electron

9. What is the surface temperature of Mercury?

60K - 400K
100K - 700K
290K - 500K
400K - 850K

10. Fill the blanks: The blue colour of the outer jovian planets is due to high percentages of __ and low percentages of __ in their atmospheres.

hydrogen, helium
nitrogen, methane
ammonia, carbon
methane, ammonia