Astro 1500 Exam 1 Review

The sun is 8 light-minutes away from us. If the sun were to suddenly go dark, how long would it take for us to notice?

• We would immediately notice

• 15 seconds

• 8 minutes

• 1-2 years

Answer explanation

The sun is 8 light minutes away, so it would take 8 minutes for the light (or lack of light) to reach us.

Why can't we make out stars from other galaxies without using advanced machinery like telescopes?

• They are redshifted out of the visible range

• They're a bit shy

• We can actually see individual stars from other galaxies

• They are too far away, making them either too dim, or too close together to see

Answer explanation

Our eyes do not have the light gathering or angular resolution of a good telescope

The ISS orbits because...

• It floats on top of the clouds

• It's moving sideways quickly enough that it 'misses' the ground

• Thrusters onboard constantly boost it upwards

• It is completely outside of the earth's gravitational influence

Answer explanation

All an orbit is, is throwing something sideways with enough velocity that when it would hit the ground, it has moved enough that the ground bends away from it (because earth is a sphere).

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The luminosity of a star depends on (among other things) ...

• It's temperature

• How far away it is from us

• How many planets it has

• Whether it's moving towards or away from us

Answer explanation

Luminosity depends on only the temperature and radius of the star. Both properties intrinsic to the star.

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A star's brightness depends on (among other things) ...

• It's metallicity (how much metal is in the star)

• How far away it is from us

• How many planets it has

• Whether it's moving towards or away from us

Answer explanation

Brightness, unlike luminosity depends on how far away the star is from us

In general, red stars are ____ than blue stars.

• Hotter

• Colder

• Closer

• Farther

Answer explanation

Color can be an allegory for temperature. Blue stars are hotter than red stars.

Jupiter orbits at a distance of roughly 5 AU from the sun, how long is a year on Jupiter (in earth years)?

• 1 earth year

• 3 earth years

• 5 earth years

• 11 earth years

Answer explanation

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The most common type of telescope used in astronomy looks at ...

• Photons / Light

• Gravity Waves

• Neutrinos

• Dust Particles

Answer explanation

Most telescopes look at the electromagnetic spectrum

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Neutrinos interact with ...

• Magnetic fields

• Electric Fields

• Other neutrinos

• Almost nothing

Answer explanation

This is why we would use neutrino telescopes (even though they are hard to make), because they pass through and are unaffected by almost everything

Say you have two stars, Star A is twice the radius of Star B, but Star B is twice the temperature of Star A. How much more luminous is Star B than Star A?

• 1/2 (meaning Star A is actually more)

• 1 (meaning they are the same)

• 2 (Star B is twice as luminous)

• 4 (Star B is four times as luminous)

Answer explanation

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