Homeworks ASTR FALL 2017
One of the nearest stars is Alpha Centauri, whose distance is 4.2 × 1016 meters. How long does it take light to travel from Alpha Centauri to us? (Hint: the speed of light is 3 x 108 meters/second)
4.4 years
According to the figure, if you were to specify your address in the universe, listing your membership from the smallest to largest physical structures, it would be:
Earth, Solar System, Milky Way, Local Group, Laniakea Supercluster, the universe.
What prevented the Moon from maintaining any atmosphere with which it originally formed?
It is not massive enough.
The radius of Jupiter is still contracting, getting ~10 centimeters smaller per century. This means:
Jupiter's rotation rate is increasing over time
If you have a stuffy nose, a fever, chills, and body aches and a doctor treats you for the flu rather than four separate diseases that account for each of your symptoms, this is an application of...
Occam's razor
Which of the following is NOT a characteristic of the early Solar System, based on current observations?
Temperatures decreased with increasing distance from the Sun.
In the absence of air friction, a 0.001-kg piece of paper and a 0.1-kg notebook are dropped from the same height and allowed to fall to the ground. How do their accelerations compare?
The accelerations are the same.
Because of _____________, we can conclude that gravity works the same way on Mars as it does on Earth.
The cosmological principle
A "light year" is a way to measure distance.
True
Our universe is approximately 13.7 _________ years old.
billion
If the distance between Earth and the Sun were doubled, the gravitational force between these two objects would:
decrease by 4
What sets the temperature of the pocket of gas in a protoplanetary disk?
its distance from the forming star, and, how much kinetic energy was converted to heat, and, how much radiation from the forming star shines on the gas
When the Sun and Moon are separated by 90 degrees in the sky, _________ tides occur on Earth when the strength of the tides are _________ than normal.
neap; lower
In science an idea that cannot be tested is...
not a scientific idea
Tidal forces are caused by...
the difference between the strength of the gravitational pull of the Moon and Sun on either side of Earth.
What is the most important factor in determining whether or not a planet will be rocky like terrestrial planets or gaseous like giant planets?
the planet's distance from the Sun
Which of the following properties of an astronaut changes when he or she is standing on the Moon, relative to when the astronaut is standing on Earth?
weight
