Astro 1500 - Exam 2 review (Fall 2025)

Angular Momentum is...

• always conserved

• never conserved

• Super cool

• not real

Answer explanation

As anything rotating shrinks, angular momentum is conserved, causing it to spin faster and flatten out. This applies to the giant clouds of gas the form solar systems

Tags

NGSS.HS-PS2-2

Parsecs are a unit of ...

• Time

• Distance

• Volume

• How long the Kessel run takes

Answer explanation

A parsec is a unit of distance of approx. 3.3 lightyears. It's found by looking at the parallax of one arcsecond over the earth's whole orbit

Tags

NGSS.HS-ESS1-4

The outermost layer of the sun is ...

• The core

• The radiative zone

• The convective zone

• The corona

Answer explanation

The corona extends millions of miles into space and is the outermost layer of the sun

Tags

NGSS.MS-ESS1-1

Which is hotter, an O type star or an A type star?

• O

• A

• More information needed

Answer explanation

The spectral classes (OBAFGKM) correlate directly to temperature. They were originally designed to line up with hydrogen line strength

A blue shifted star is moving (towards/away) from us.

• Towards

• Away

Answer explanation

This blue/red shift is called the doppler effect, it can tell us many things about a star, such as it's radial velocity, if it has planets, and it's rotation speed.

Tags

NGSS.HS-PS4-1

NGSS.HS-PS4-3

If star 1 and star 2 are the same brightness then ...

• Star 1 is hotter, while star 2 is closer

• Star 1 is larger, while star 2 is hotter

• They are the same in every way

• Any of these options

Answer explanation

Brightness depends on distance and luminosity, which depends on size and temperature. So brightness can be determined / affected by any of these things

The mass of a binary star system can be determined by ...

• Looking at their brightnesses

• Asking them nicely

• Looking at how they orbit each-other and using kepler's laws

• Looking at their helium lines

Answer explanation

Using the doppler effect, we can look at the orbits of 2 stars and find their masses. This is super useful as it allows us to correlate mass with other metrics to find the mass of non-binary stars.

Tags

NGSS.HS-ESS1-4

Background light passes through a cloud of ISM dust, less light makes it through. This is called

• Absorption

• Emission

• Aberration

• A grand ole time

Answer explanation

Dust can absorb light, but is can also emit some light and redden it as well

Tags

NGSS.HS-PS4-4

What is the solar composition? (select the most correct answer)

• 70% Hydrogen, 30% helium

• 72% Hydrogen, 26% helium, 2% metals

• 100% metal

• 90% helium, 5% hydrogen, 5% metals

Answer explanation

The sun is mostly hydrogen and some helium, with a tiny amount of "metals". In astronomy Metal can be anything heavier the H and He, like oxygen, carbon, lithium, silver etc.

Tags

NGSS.HS-ESS1-1

NGSS.HS-ESS1-3

You would expect a given object to have a spectral line at 490 nm, but you see one at 495 nm. What does this tell you about the object.

• It's moving towards you very quickly

• It's moving away from you very quickly

• It's spinning

• The object is blue

Answer explanation

A shift towards the redder end of the spectrum corresponds to a red doppler shift. meaning the object is moving away

Tags

NGSS.HS-PS4-1

NGSS.HS-PS4-3