a star that appears to be double, but it's really an optical illusion caused by Earth's atmosphere
two stars that appear to be close together in our line of sight, but are really light-years apart
a star that appears to be a double, caused by bad collimation of a telescope
a star and with companion gas-giant planet, which reflects as much light as its parent star

2. Which planets feature "shield volcanoes"?

Mercury, Pluto
Venus, Earth, Mars
Jupiter, Uranus
Saturn, Neptune

3. What is "perihelion"?

the closest approach of an object to the Sun
the farthest position of an object away from the Sun
the point at which the Sun's gravity seizes to effect an object
the point at which an object enters the solar atmosphere

4. Why would an astronaut on Mars not be able to use a compass to find the way?

beacuse Mars's large metallic core would send the needle spinning in all directions
because Mars's two moons, Phobos and Deimos, are heavily magnetized and would influence the compass
because Mars's north and south magnetic poles switch eratically
because Mars has no magnetic iron core

5. Where would you find the "Valhalla" ring basin?

Mars
Moon
Callisto
Triton

6. What is the "local group"?

a group of about 30 galaxies, including our own galaxy, located within roughly 4 mil. light-years
a group of about 90 nearby stars, including our Sun, located within roughly 25 light-years
the open star cluster Hyades, which lies only 150 light-years away from the Sun
the globular star cluster M4 in Scorpius, which lies only 7,000 light-years away from the Sun

7. The Messier Object M8, the Lagoon Nebula, is a -

reflection nebula
emission nebula
emission and reflection nebula
planetary nebula

8. Kepler's discoveries regarding the motions of the planets were based on the observations of -

Nicholas Copernicus
Artistarcus
Tycho Brahe
Ptolemy

9. What is an"Airy disk"?

an adjustable polarized filter, allowing for observation of the Moon at various phases
a disk of gas and dust found in some elliptical galaxies, likely due to a merger of an elliptical and a spiral galaxy
the spherical shell of cool and thin matter surrounding the carbon core of a planetary nebula
the circle over which a star's light is spread in a telescope due to diffraction

10. What are the "Van Allen Belts"?

two regions near Earth's north and south poles, where aurorae borealis/australis appear
two regions of magnetically trapped particles, high above Earth's atmosphere
two regions just north and south of the equator, where solar winds are most likely to hit
three regions above Earth's atmosphere where most geosyncronous satelites are placed