Astronomy mid-term 1

True or False: if students on a planet circling a star in the Andromeda Galaxy were to use a powerful telescope to observe our solar system, they could study the human impact on Earth.

False

Why can't we see a galaxy 15 billion light-years away?(Assume the universe is 14 billion years old.)

Because looking 15 billion light-years away means looking to a time before the universe existed.

Let's reduce the size of the solar system by a factor of 10 billion; the Sun is now the size of a large grapefruit (14 centimeter diameter).How big is Earth on this scale?

a ball point

On our 1-to-10-billion scale, it's just a few minutes' walk to Pluto.How far would you have to walk to reach Alpha Centauri, the nearest star system to our solar system?

1 mile

Suppose you tried to count the more than 100 billion stars in our galaxy, at a rate of one per second.How long would it take you?

a few thousand years

Suppose that 1 out of 1 million stars had a planet around it...How many other planets with life would there be within the Milky Way?

One-hundred thousand other planets with life

Where did the heavier elements like carbon, nitrogen, oxygen, and iron come from?

These elements are manufactured by stars as they undergo nuclear fusion

In space, how is direction typically specified?

Direction can be given the same as on Earth: North, South, East, West

Why are collisions between star systems extremely rare?

The relative distance between stars is so much larger than the size of stars.

The brightest stars in a constellation

may actually be quite far away from each other.

Would we be able to see with our naked eyes another galaxy that lies in the same direction of our Milky Way center?

No, the clouds within the Milky Way obscure our view beyond our galaxy in this direction

The angular size of your finger at arm's length is about 1°. How many arcseconds is this?

60 ×60 = 3600 arcseconds

True or False: The Earth and the Moon are both extend approximately half a degree in our sky. This means that they are both the same physical size.

False

What is the arrow pointing to in the photo below?

North Celestial Pole

Now knowing how stars appear to move in our sky, how would galaxies move in our sky?

They are also on the celestial sphere and would move in the same pattern as stars

The North Star (Polaris) is 50°above your horizon, due north. Where are you?

You are on the equator.

True or False: Earth is closer to the Sun in summer and farther from the Sun in winter.

False

Which of the locations identified with an "x" for each of the situations (A - E) would experience the coolest temperature over the course of one day?

D Tilt 90 degrees

It's 9 a.m. You look up in the sky and see a moon with half its face bright and half dark. What phase is it?

third quarter

How long would each day and night last if you lived on the Moon?

2 weeks

Uranus is faintly visible to the naked eye but it was not recognized as a planet in ancient times. If the planet was brighter and recognized as a planet, what might be different about the current calendar organization?

Week would have 8 days instead of 7

In ancient Greece, knowledge was likely passed down via

books and scrolls

Which of the following is NOT a fundamental difference between the geocentric and Sun-centered models of the solar system?

The geocentric model is useless for predicting planetary positions in the sky, while even the earliest Sun-centered models worked almost perfectly.

Suppose a comet has an orbit that brings it quite close to the Sun at its perihelion and beyond Mars at its aphelion, but with an average distance (semimajor axis) of 1 AU. How long would it take the comet to make one complete orbit around the Sun?

The same time Earth takes to complete an orbit or 1 year

An asteroid orbits the Sun at an average distance a = 4 AU. How long does it take to orbit the Sun?

8 years

Darwin's theory of evolution by natural selection meets all the criteria of a scientific theory. This means:

After more than 100 years of testing, Darwin's theory stands stronger than ever, having successfully met every scientific challenge to its validity

For each of the following is there a net force on the object described? Y/N

1.A car coming to a stop: Y
2.A bus speeding up: Y
3.An elevator moving at constant speed: N
4.A bicycle going around a curve: Y
5.A moon orbiting Jupiter: Y

The gravitational force on the Moon is weaker than on the Earth. This means that on the Moon:

My weight is less, my mass is the same.

How does the force the Earth exerts on you compare with the force you exert on the Earth?

Earth and you exert equal and opposite forces on each other.

A compact car and a large truck have a head-on collision. Are the following true or false?
1.The force of the car on the truck is equal and opposite to the force of the truck on the car.
2. The momentum transferred from the truck to the car is equal and opposite to the momentum transferred from the car to the truck.
3. The change of velocity of the car is the same as the change of velocity of the truck.

1. true
2. true
3. false

If the distance between two masses is doubled, the gravitational force between the masses

decreases by a factor of 4

Consider two objects being dropped from one meter above the surface of the moon: a hammer and a feather. Are the following true or false?
1. The force due to gravity on the hammer and feather are equal.
2. The acceleration of the hammer and feather are equal.
3. The mass of the hammer and feather are equal.

1. False
2. True
3. False

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

very near the center of the galaxy