ISP 205 Exam 1

Cosmic Address, from small to large

Earth, solar system, Milky Way Galaxy, Local Group, Local Supercluster, universe

The Universe is expanding means that...

The average distance between galaxies is growing with time

If stars existed but galaxies did not...

We would not exist because we are made of material that required recycling in galaxies.

Could we see a galaxy 20 billion light years away?

No, because it would be beyond the bounds of our observable universe

The star Betelgeuse is about 425 light-years away. If it explodes tonight:

We won't know about until 425 years from now

If we represent the solar system on a scale that allows us to walk from the Sun to Pluto in a few minutes, then:

the planets would all be marble size or smaller and the nearest stars would be thousands of miles away.

The total number of stars in the observable universe is roughly equivalent to:

the number of grains of sand on all the beaches on Earth.

The age of our solar system is about

one-third of the age of the universe.

An astronomical unit (AU) is...

Earth's average distance from the Sun

The fact that nearly all galaxies are moving away from us, with more distant ones moving faster, helped us to conclude that:

The universe is expanding

In what sense are we "star stuff"?

Nearly every atom from which we are made was once inside of a star

Why are galaxies important to our existence?

Galaxies recycle material from one generation of stars to the next, and without this recycling we could not exist.

When we look at an object that is 1,000 light-years away we see it _________

as it was 1000 years ago

Suppose we look at two distant galaxies: Galaxy 1 is twice as far away as Galaxy 2. In that case ________

we are seeing Galaxy 1 as it looked at an earlier time in the history of the universe than Galaxy 2

Suppose we make a scale model of our solar system, with the Sun the size of a grapefruit. Which of the following best describes what the planets would look like?

The planets are all much smaller than the Sun. Four planets are within about 20 meters of the Sun, while the rest planets are spread much farther apart

If you could count stars at a rate of about one per second, how long would it take to count all the stars in the Milky Way Galaxy?

Several thousand years

Where is our solar system located within the Milky Way Galaxy?

Roughly halfway between the center and the edge of the visible disk of the galaxy

If we imagine the history of the universe compressed into one year, dinosaurs became extinct _________.

Yesterday morning

How do the speeds at which we are moving with Earth's rotation and orbit compare to the speeds of more familiar objects?

Earth's rotation carries most people around the axis faster than a commercial jet travels, and Earth's orbit carries us around the Sun faster than the Space Shuttle orbits Earth.

Why do the patterns of the stars in our sky look the same from year to year?

Because the stars in the constellations are so far away

In winter, Earth's axis points toward the star Polaris. In spring:

the axis also points toward Polaris

If the Sun rises precisely due east:

it must be the day of either the spring or fall equinox

A week after full moon, the Moon's phase is:

Third Quarter

Some type of lunar or solar eclipse (not necessarily a total eclipse) occurs

at least four times a year

If there is going to be a total lunar eclipse tonight, then you know that:

The moon is full

An angle of 1 arcsecond is ________

less than the thickness of a human hair held at arm's length

How does a 12-month lunar calendar differ from our 12-month solar calendar?

11 fewer days

Compared to an atom as a whole, an atomic nucleus:

is very tiny but has most of the mass.

Radio waves are...

a form of light

A star whose spectrum peaks in the infrared is:

cooler than our Sun

When moving farther away, an object is...

redshifted

why do we say that light is an electromagnetic wave?

The passage of a light wave can cause electrically charged particles to move up and down.