Intro to Modern Cosmos

let c the speed of light in a reference frame S and c' the speed of light in another frame S' moving relatively to S with the speed 0.5c. According to Galilean's transformation, the speed of light c' should be

1.5c

Why is the use of Hubble's Law to measure distances to galaxies so important to astronomers?

Most galaxies are so far away, the only way to get distances to them is to use Hubble's Law

a train is moving with a constant speed relative to the ground that means

a person on the train and a person on the ground are twi different inertial frames

According to Galileo and Newton, which of the following frame of references cannot be considered as inertial frame of references?

a satellite orbiting the earth

Factoring in everything we currently know about the history of the universe, our best estimate for the age of the universe is

about 14 billion years

What type of main sequence star is most likely to become a black hole?

an O-type star

which of the following statements about the violent events on the sun called flares is false?

astronomers think that flares are connected with sudden changes in the magnetic field of the sun

Albert is moving away fro me at the half speed of light (0.8). he sends a beam of light back towards me that he measures to be moving at speed c relative to him, what speed does the light approach me as measured in my frame?

c

coronal mass ejections from the sun have many serious effects on or near the earth. which of the following is not one of these effects?

causing huge cyclones around the equator of the earth

The ten million tons of particles that escape the Sun each year in the in the form of the solar wind get out mainly through regions called

coronal holes

according to Galilean transformation, the speed of light measured by two different observers (the observer on the train and the observer on the ground) is:

different if the train is moving relative to the ground

One of the main projects being carried out by the Hubble Space Telescope is to measure the distances of galaxies located in groups dozens of millions of lightyears away. What method do astronomers use with the Hubble to find such distances?

finding Cepheid variables (variable stars) and measuring their periods

which of the following is not part of some active regions on the sun?

granulation

To predict whether a star will ultimately become a black hole, what is the key property of the star we should look at?

mass

You are out on the beach, enjoying the warm sunshine with friends. As you glance up at the Sun (only briefly we hope), the part of the Sun that you can see directly is called its:

photosphere

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

the age of the universe

The region around a black hole where everything is trapped, and nothing can get out to interact with the rest of the universe, is called

the event horizon

According to Galilean transformation, the speed of the ball is same for the observer on the train and the observer on the ground if

the train is not moving relative to the ground

Sunspots are darker than the regions of the Sun around them because

they are cooler than the material around them (although still very hot compared to Earth temperatures)

according to Galilean relativity, which of the following quantity is not relative

time

How do astronomers know what the outer layers of the Sun are made of?

we take an absorption line spectrum of the Sun, and the absorption lines tell us what elements are present in the outer layers

Which of the following can a black hole not "eat" (swallow)?

you can't fool me, black holes can eat anything

In a distant galaxy, whose light is just arriving from 10 billion light years away, our spectroscope should reveal that the most common element is

hydrogen

Which of the following statements about the implications of Hubble's Law is FALSE?

if you were observing the universe from a distant galaxy, you would NOT see all the galaxies (except those in your own group) moving away from YOU

As astronomers have learned more about the structure of the Sun, they have found that it

it is made entirely of hot gas

Deep inside a black hole (and hidden from our view) is the compressed center, where all the "stuff" of the star goes. Astronomer call this central point

singularity

Once a black hole forms, the size of its event horizon is determined only by

the mass inside the event horizon

In the far future, a starship becomes trapped inside the event horizon of a black hole. Although the crew discovers that their ship cannot out, they at least want to send a message to other ships in the area to stay away from the danger zone. If they send out a message in the form of a radio wave, what will be its fate?

the message will never emerge from the event horizon

Before you can use Hubble's Law to get the distance to a galaxy, what observation must you make of that galaxy?

you must take a spectrum of the galaxy and measure the red shift