Astronomy & Cosmology Final

Why do astronomers use radio and infrared telescopes to study the structure of the milky way?

Dust in the milky way blocks most of the visible light, but radio and infrared wavelengths can pass through the dust and reveal stars and spiral structure.

After the GUT era, the universe went through a fast expansion. What causes the tiny anisotropies that showed up afterward?

Quantum fluctuations stretched by rapid expansion

In which era did the formations of elements like hydrogen and helium occur?

The era of nucleosynthesis 

What is evidence that the early universe had a period of inflation?

The CMB has an almost perfectly uniform temperature with tiny fluctuations indicating that regions once far apart were stretched with a much smaller connected patch.

What galaxy category necessarily three distinct parts? (bulge, disk, halo)

Spiral Galaxy

A distant galaxies spectrum lines show that one of its absorption lines has shifted from 400nm to 460nm. What is the explanation for this?

The galaxy is moving away from us

What does the blue white color of an irregular galaxy tell us?

It has active star formation

What is the oldest light we can observe in the universe?

The cosmic microwave background

In what ways do the theories of the general relativity and quantum mechanics become difficult to reconcile?

They have trouble resolving what happened in the Planck era and they break down in regime of high energy and small distance

Hubbles law implies…

In the past the universe was much hotter and denser and has been cooling and expanding ever since

Why is the cosmic microwave background radiation observed today in the microwave part of the electromagnectic spectrum?

The expansion of the universe stretched the original thermal radiation to longer wavelengths 

What astronomical object is considered a standard candle and can be used to measure distances to very far off galaxies because of its extremely high and consistent peak luminosity?

Type 1a supernovae

What percent of mass and energy contents of the universe is not made from dark matter/energy?

5%

What type pf galaxy is most common within large galaxy clusters?

Elliptical galaxies tend to have large galaxy clusters

What is the primary evidence for the existence of dark matter in galaxies?

The faster than expected rotation speed of stars far from galactic centers

According to hubbles law, what does it mean if galaxy B is moving away twice as fast as galaxy A?

Galaxy B is twice as far as A

Rotation curves in other galaxies are measured by?

Using the doppler shift

Which of the following most resembles the overall shape of our Galaxy?

a flattened disk, like a pizza, a bit thicker in the middle

 Our Milky Way Galaxy is what type of galaxy?

Spiral

Which kind of main-sequence star is most likely to be part of the halo population of the Milky Way?

an M star

Stars in our Milky Way farther out than the Sun's orbit are still orbiting our Galaxy with high speeds. What do we learn from that?

there is likely a great deal of invisible dark matter surrounding our Galaxy whose gravitational pull causes the fast motion

Where would you look for the youngest stars in the Milky Way Galaxy?

in the spiral arms in the disk of the Galaxy

If a galaxy contains a great deal of dark matter, what will that do the galaxy’s mass-to-light ratio?

Increase it a great deal

Quasars are 

very powerful and compact sources of energy at the centers of distant galaxies

Edwin Hubble showed that the farther a galaxy is from us, the

the faster its moving away from us

According to Hubble's Law, if Galaxy B is moving away from us three times as fast as Galaxy A, then Galaxy B is

is three times farther way from us than Galaxy A

Why is using Hubble’s Law to measure distances to galaxies so important in astronomy?

most galaxies are so far away that  the only way to get distances to them is to use Hubble’s Law

Why are giant elliptical galaxies often found near the centers of galaxy clusters?

giant elliptical galaxies form by merging or swallowing other galaxies and those are plentiful near the center of galaxy clusters

What elements were formed in the early Universe in the first few minutes after the Big Bang

hydrogen, helium, and a tiny bit of lithium

Which of the following describes the evolution of the temperature in the Universe after the Big Bang?

it started out hot and has been cooling down ever since

A hydrogen nucleus has just one proton. What is the name of the atomic nucleus containing one proton and one neutron? It is an isotope of hydrogen.

deuterium

Where in space did the expansion of the universe begin?

everywhere all at once

Why is the Cosmic Microwave Background (CMB) the earliest time we can see the Universe with light?

before the CMB the universe was opague to light

If you could see the light filling the Universe at the time the Cosmic Microwave Background was formed, what would you see?

Red Light

Which best describes the Cosmic Microwave Background?

It is quite uniform across the sky, but with very small fluctuations

What does it mean to say that the Universe underwent a period of inflation at early times?

the universe expanded at an extremely rapid rate

Dark matter is inferred to exist because

we observe its gravitational effects on visible matter

The rotation curves of spiral galaxies like the Milky Way show

stars and gas in the outer parts of the galaxy are rotating faster than expected based on the visible matter

Which of the following best describes how galaxies are distributed in the Universe?

most galaxies are in sheets and filaments of the cosmic web and very few galaxies are in cosmic voids

Approximately what fraction of the critical density of the Universe is dark matter?

27%

The reciprocal of the Hubble constant (1/H) is a rough measure of

the age of the universe

Evidence for the accelerating expansion of the Universe comes from observations of

white dwarf (Type Ia) supernovae

According to our textbook, roughly what percent of the mass and energy contents of the universe is made up of dark matter plus dark energy?

95%

Some scientists speculate that the properties (laws) of the universe must be the way they are because if they were significantly different, we would not be here to think about them. This idea is called

anthropic principle

Which of the following describes how dark matter and dark energy affect the expansion of the Universe over time?

dark matter slows down the expansion of the Universe, dark energy speeds it up

Think for a moment about an atom of iron in your breakfast spoon (or in the hemoglobin in your blood!). In which of the following places has this atom of iron probably NOT been during the course of its existence?

the sun

What is the Fermi paradox?

If intelligent life were common in the Milky Way, why is there no sign of it in the Solar System?

A habitable planet is one that

is one potentially capable of having life

For the complex biochemical reactions of life (as we know it) to happen, a solvent is required.  What is that solvent for life on Earth?

water

The Drake Equation allows astronomers to estimate

the number of civilizations out among the stars with which we might communicate

What galaxy contains mostly older stars?

Elliptical

What is the difference between elliptical and spiral galaxies?

Elliptical galaxies have less gas and dust than spiral galaxies.

Dark Matter slows down expansion while Dark energy…

speeds up expansion

Age of the universe

Universe formed about 14 billion years ago

Evidence for the Big Bang?

The universe is expanding, the cosmic microwave background and the prediction of abundance of hydrogen and helium