Midterm TopHat Study Guide
What is (4.2 x 10^-2) / (8.4 x 10^-5)
0.5 x 10^3 500
Suppose the Sun were somehow replaced by a star with twice as much mass. What would happen to the gravitational force between Earth and the Sun? (Submit the multiplier: 0.25 for 1/4th the force, 0.5 for half the force, 1 for same force, 2 for twice the force, 4 for four times the force. etc.)
2
What is (6x10^2) x (4x10^5)
2.4 x 10^8 24 x 10^7 240 million
Our Sun is about 27,000 ly away from the galactic center and orbiting around it. Estimate, how long does it take for Sun to complete one full circle around the center of our galaxy?
230 million years
What is the acceleration of gravity (g-factor) on Mars' surface? (Give your answer in m/s^2, submit just the number w/o typing the unit)
3.7
What is 3x10^8
300 million
What is the mass of our Sun? (Guess)
300,000 x the mass of Earth
Suppose a human body (of typical mass) could run on fusion power and could convert 0.5 % of its mass into energy. How much energy would be available through fusion?
3×10^16 J
If we would squeeze the life of the universe into one year, at what date and time did humans learn to write using letters?
Dec. 31, 11:59 pm
Which is the most abundant element in the universe
Hydrogen
Which of the following is Kepler's 3rd law?
T2 = p3 The square of a planet's orbital period is proportional to the cube of the length of the semi-major axis of its orbit Planets with larger orbits orbit the Sun at slower average speeds than planets with smaller orbits.
Why is the AU still a useful unit?
The AU provides a good comparison to see how close things are based on the distance we know, the distance between Earth and the Sun
Which of the following statements about the Sun's photosphere is NOT TRUE?
The photosphere is significantly hotter than all the layers of the Sun beneath it (further inward)
Your weight on Earth is simply the gravitational force between you and Earth. Would your weight be more, less, or the same on Mars? (Note that Mars is both, smaller and less massive)
not enough information
The Sun is an enormous ball of gas. Left to itself, a ball of so many atoms should collapse under its own tremendous gravity. Why is our Sun not collapsing?
nuclear fusion in the core keeps the temperature and the pressure inside the Sun at a high enough level so that gravity is balanced
During what lunar phase do solar eclipses occur?
new moon
"Will summer always be summer?" (Will Earth always be farthest away from Sun in Northern-Hemisphere summer?)
no
Hypothetically, if we could capture and store all the energy our Sun releases in 1 second, for how long could we power the U.S. (total energy consumption of U.S., incl. homes, businesses, industry, traffic, ...)
1 million years
List at least three disadvantages of the unit AU.
1. It is only based off of the distance between the Earth and Sun so it is not as useful as calculating other distances. 2. The number is a rough estimate because we cannot calculate the exact distance, and the Sun is losing mass making the number change over time. 3. It is a bit outdated because it was created in the early days of astronomy when it was the most important thing to measure.
On the Equator, you would travel 40,000 km, the circumference of Earth, in 24 hours. What is this speed in miles per hour? (Enter the number without unit)
1036
According to Table 1.1, how much more Carbon is there in the universe compared to Magnesium? (If there is more Magnesium than Carbon, this would be a number smaller than 1. For example, if there is twice as much Magnesium than Iron, submit 0.5).
11
Calculate the minimum velocity a spaceship would still need to have to be able to escape from our solar system when it is already 9.5 AU away from the Sun. Give your answer in km/s.
13
8 light minutes are
150 million km 1 AU
How many AUs are one light year? (Round reasonably)
63,000
Suppose Earth were moved to one-third of its current distance from the Sun. What would happen to the gravitational force between Earth and the Sun? (Submit the multiplier: 0.25 for 1/4th the force, 0.5 for half the force, 1 for same force, 2 for twice the force, 4 for four times the force. etc.)
9
How does Earth move across the "sky" on the Moon? (Standing on the Moon, how would you see Earth moving?)
Earth would stand still (always at the same position in the "sky") but rotate.
The Earth is currently closest to the Sun in which month of the year?
January
Which of the following is the correct ordering from largest to smallest?
Local Supercluster, Local Group, Milky Way, Solar System
What other planet is known to have different seasons?
Mars, Saturn, Uranus, and Neptune
Why don't we see a lunar and a solar eclipse every month?
Moon's orbit is tilted, so Sun, Earth, and Moon only align twice each year.
How does the number of stars in the observable universe compare to the number of grains of sand on earths beaches?
On astronomical scales, the numbers are about the same
If Zenith and the North Celestial Pole are at the same position, where are you?
On the North Pole
Which of these galaxies is closest to Milky Way?
The Sagittarius dwarf galaxy
How does the Sun influence the tides that we experience on Earth?
The Sun also raises tides on Earth, but its effect is smaller than that of the Moon
How can it be that two protons fuse together in the first place? They are positively charged particles and repel each other.
They only repel each other at large distances. When they are close together they attract each other. That's right, they do almost always repel each other. They have to be slammed into each other at high speeds. The high pressure in the core is stronger than the repulsive force.
How far away from our Sun is the next closest star?
a few light years more than 20 Trillion miles
What does a force acting on an object do to that object's motion? (Ignore relativistic effects)
a force changes an object's momentum
At the end of the p-p chain of nuclear fusion in the Sun, hydrogen nuclei have been converted into
a helium nucleus
According to the formula E=mc2
a little bit of mass can be converted into a substantial amount of energy
According to the formula E=mc^2
a little bit of mass can be converted into a substantial amount of energy
The power needed to operate your body is about 100 watts. For how long could this body then operate on fusion power? (Use the result from the previous question)
about 10 million years
A friend of yours tells you about a report they have read in a tabloid newspaper. It is claimed that on the dark side of the Moon, which is never in sunlight, there is a secret base of aliens who cannot stand light, and who send UFO's to Earth under the cover of darkness. Ignoring the UFO claim for a moment, what is the scientific error in this story?
all sides of the Moon are illuminated by sunlight in the course of a month; there is no dark side
What is the speed of Earth orbiting Sun?
approx. 67,000 mph 2pi1AU/365 days
If you could see the new moon, at what time of day (roughly) would it rise?
at sunrise
Solar wind particles can be captured by the Earth's magnetosphere. When these particles spiral down along the magnetic field into the atmosphere, they are responsible for:
aurorae
The hotter region directly above the Sun's visible surface is called the
chromosphere
Which part of the Sun has the greatest density?
core
Will the marker come back if you throw it upwards with a ridiculously high speed?
depends on the speed will be gone forever
If distance from the Sun is not the reason, what is the reason for seasons?
different amount of light due to axis tilt
What is the difference between energy and power?
energy = power x time
If the "fuel" for nuclear fusion is nuclei of hydrogen, and the Earth's oceans are filled with hydrogen atoms in water all being jostled together, why isn't there a lot of fusion happening in our oceans?
for hydrogen nuclei to fuse, they must get very close to each other, which the nuclei in the oceans cannot do
During what lunar phase do lunar eclipses occur?
full moon
When a ball is dropped, some of the ball's energy changes from
gravitational potential energy to kinetic energy.
At the center of the Sun, fusion converts hydrogen into
helium, energy, and neutrinos
The most common element in the Sun is
hydrogen
As astronomers have learned more about the structure of the Sun, they have found that it
is made entirely of hot gas
Earth is closer to the Sun in summer and farther from the Sun in winter.
it depends on whether we are in the Northern or Southern hemisphere
Which of the following statements about the Sun's photosphere are true? (must check all that apply for credit)
it is not a solid later it is the layer where the Sun becomes opaque
A friend of yours who takes her astronomy class very seriously challenges you to a contest to find the thinnest crescent moon you can find just after new moon? What time of day is best for looking for this very thin crescent?
just as the sun is setting, or just after
Which of these facts about Sun are correct? (Check all that apply)
mainly made up of H (70%) and He (28%) radius: 7 x 10^5 km mass: 2 x 10^30kg rotation rate: 25-30 days surface temp.: 5800K luminosity: 3.8 x 10^26 watts
A very rich, very shady international banker (with residences all over the globe, including Bayonne, New Jersey) mysteriously disappears. Someone later mails a wide-angle photo of their body to a London newspaper, taken on June 22, showing the Sun exactly overhead at noon. What can the police deduce from this photograph about where on Earth the body is located?
on the Tropic of Cancer (23deg N)
Which of these layers of the Sun is the coolest?
photosphere
You are out on the beach, enjoying the warm sunshine with friends. As you glance up at the Sun (only very(!) briefly), the part of the Sun that you can see directly is called its:
photosphere
You are out on the beach, enjoying the warm sunshine with friends. If you would you glance up at the Sun (not that you ever want to do that!), the part of the Sun that you would see directly is called its:
photosphere
The material inside the Sun's core is in the form of a
plasma
Which of the following is NOT one of the fundamental particles that we find inside atoms?
positrons
A writer of mystery novels wants to portray something gruesome happening just as the full moon is at its highest point in the sky. What time of day will the gruesome event occur?
roughly midnight
When two light elements collide to undergo nuclear fusion
some of the energy in their mass is released
In the formula E=mc2, the letter c stands for
speed of light
When the Sun and Moon are lined up and pull together, the tides they raise are called:
spring tides
In what location on Earth could you not use her solar-powered calculator at any time at all during the course of a day in June?
the South Pole
Which of the following are important parts of the reasons it is hotter in summer in North America than in winter? (must chose all correct answers for credit)
the Sun's rays hit Earth more directly in the summer and spread out less in summer the Sun rises North of East resulting in a longer time the Sun spends above the horizon
Why does the Moon show phases in the course of a month?
the angle the Moon makes with the Sun changes and we see differing amounts of reflected sunlight
If you could somehow return to the Earth in many millions of years, which of the following will noticeably be different?
the length of the month
Why do we only see one side of the moon?
the moon rotates and revolves at the same rate
A college friend of yours who has been postponing taking any science courses hears you talking about the generation of nuclear energy in the Sun and makes the following observation: "The whole idea of the atomic nucleus is pretty ridiculous. If an oxygen nucleus consists of eight protons and eight neutrons, the charge on that nucleus is positive. Since even I learned in high school that like charges repel, such a nucleus would find all its positive protons repelling and quickly fall apart." How would you answer his argument?
the nuclear force, which is attractive over short distances like the nucleus, and stronger than electricity, holds the nucleus together
For scientists, an element (like gold) is defined by
the number of protons in its nucleus
The Sun's photosphere is (check all that apply)
the part of the Sun from which the light comes that we see when we look at the Sun with our eyes the coldest region of the Sun
The period of the moon's rotation on its axis is
the same as its revolution around the Earth
What would you have to change about the Earth to stop our planet from having significantly different seasons?
the tilt of the axis
If you put your hand in boiling water at 100C (373K, 212F) your skin will burn immediately. Why does it not when you take the cake out of the oven at 200C (473K, 392F)?
there is more energy in water, it's much denser
Space Station astronauts are weightless because
they are in constant free fall
We always see the same side of the moon.
true
What element will never be found in the Sun?
water
Does our Sun rotate?
yes
Given that the ISS is only 400km above ground, would launching space craft from ISS make much sense?
yes
Does our Sun cause/influence tides on Earth?
yes, they overlap with the tides from the Moon
