Astro 1500 Final Exam Review Part 1 (exams 1 and 2)

If I am two light-nanoseconds away from you, how old do I appear to you compared to my actual age?

• One light nano-second younger

• 2 light nano-seconds older

• Same as my actual age

• 2 light nano-seconds younger

Answer explanation

By the time my light reaches your eyes, I have already aged two light nanoseconds, therefore I appear two light nanoseconds younger. (As an aside, a light nanosecond is pretty close to a foot in length)

The hypothesized planet nine would orbit around 500 AU from the sun, using Kepler's 3rd law, what would be it's period in years?

• 63 years

• 11,180 years

• 1,450 years

• 101,600 years

Answer explanation

P^2 = a^3, so we have a semi major axis of 500 AU, which is a. Here, (a^3)^0.5 = P = 11180 years, a very long time.

Tags

NGSS.HS-ESS1-4

What did the Copernican revolution represent in terms of how humans think about the Universe?

• We learned to use intuition and divine revelation to answer questions

• We realized that gravity is both responsible for things falling to Earth and keeping planets in orbit.

• We found ways to observe the Universe and as such, astronomy was born

• We learned to use empirical evidence to answer questions

Answer explanation

Copernicus used actual data to justify his claims, not just trying to logic it out like the greeks and others did

Tags

CCSS.RI.8.1

CCSS.RI.8.8

CCSS.RL.11-12.1

CCSS.RL.8.1

CCSS.RL.9-10.1

You observe two stars. Star #1 looks blue, and Star #2 looks red. Which one has a lower temperature?

• Star 1

• Star 2

• We cannot know with this information

Answer explanation

Very hot stars will glow blue, so red is a lower temperature. This is due to wien's law again, a lower wavelength corresponds to a higher temperature, as is seen in the previous question.

Tags

NGSS.HS-PS4-3

Let’s say that you build your own radio interferometer consisting of two dishes. You keep the dishes the same size, but move them farther apart. In doing so, which of the following is true about resolving power and light gathering power?

• 
  The light gathering power remains the same, while the resolving power becomes better.

• 
  Both the resolving power and the light gathering power become better.

• The resolving power remains the same, while the light gathering power becomes better.

• Both the resolving power and the light gathering power stays the same.

Answer explanation

The distance is what affects the resolving power.

Tags

NGSS.HS-PS4-3

True or False: This is a picture of the milky way.

• True

• False

Answer explanation

False, we are in the milky way and cannot take a photo like this of it, this is a photo of another galaxy we think is similar to ours

Tags

NGSS.HS-ESS1-2

Order the types of light from most to least energetic

• Gamma, X-ray, visible, UV, Radio, IR, Microwaves

• Microwaves, Radio, UV, Visible, X-Ray, IR, Gamma

• Radio, Microwaves, IR, Visible, UV, X-ray. Gamma

• Gamma, X-ray, UV, Visible, IR, Microwaves, Radio

Answer explanation

Gamma rays are the most energetic, the order follows: Gamma, X-ray, UV, Visible, IR, Microwaves, Radio

Tags

NGSS.HS-PS4-1

What happens to an electron in an atom that produces an emission line?

• It goes to a lower energy orbit

• It goes to a higher energy orbit

• Nothing

• It leaves the atom

Answer explanation

When an electron jumps from a higher to a lower energy level, it emits some energy in the form of a photon (ie an emission line)

Tags

NGSS.HS-PS4-3

NGSS.HS-PS1-2

Everything else remaining the same, if you triple a star's temperature, the luminosity increases by __ times.

• 3

• 9

• 27

• 81

Answer explanation

All else remaining the same, the only thing that matters is the temperature, so T^4 --> (3)^4 = 81 times more luminous.

A wavelength of 0.001 m corresponds to a temperature of what? (Hint: Use Wien's law)

• 1. 1.2 K

• 2.9 K

• 12 K

• 29 K

Answer explanation

λ = 2.9*10^3/T, thus T = 2.9*10^3/lambda and T = 2.9*10^3/0.001 = 2.9. (Show on board)

Tags

CCSS.8.EE.C.7B