56 terms


Which of these are not associated with the active Sun?
The outward pressure of hot gas in the Sun...
is balanced by the inward gravitational pressure.
A loop of gas following the magnetic field lines between sunspots' poles is
How long does the sunspot cycle last, on average?
about 11 years
The most striking example of solar variability was the
Maunder Minimum
come in pairs, representing the north and south magnetic fields.
Sunspots are dark splotches on the Sun. Which statement is true?
-They are associated with areas of very low magnetic fields.
-They are hotter than the surrounding areas of the Sun.
-They are extremely cold objects, as cold as Pluto.
-They are extremely hot, but cooler than the surrounding areas of the Sun.
-They are solid bodies floating on the surface of the Sun.
They are extremely hot, but cooler than the surrounding areas of the sun.
What natural barrier tries to prevent two protons from combining?
electromagnetic repulsion
The critical temperature to initiate the proton-proton cycle in the cores of stars is:
10 million K
In the proton-proton cycle, the helium atom and neutrino have less mass than the original hydrogen. What happens to the "lost" mass?
It is converted to energy.
In the proton-proton cycle, the positron is
an anti-electron
Which is the net result of the proton-proton chain?
4 protons = 1 helium 4 + 2 neutrinos + gamma rays
Consider the four stars shown following. Rank the stars based on their surface temperature from highest to lowest.
red supergiant star
orange main-sequence star
blue white dwarf star
highest: blue white dwarf star
orange main-sequence star
lowest: red supergiant star
Listed following is a set of statements describing individual stars or characteristics of stars. Match these to the appropriate object category.
A)red giant or supergiant
B)main sequence stars
C)white dwarfs
1. The majority of stars in our galaxy
2. very cool but very luminous
3. not much larger in radius than Earth
4. very hot but very dim
5. the Sun, for example
6. found in the upper right of the H-R diagram
7. a very hot and very luminous star
A) 2, 6
B) 1, 5, 7
C) 3, 4
Compared to a main-sequence star with a short lifetime, a main-sequence star with a long lifetime is
less luminous, cooler, smaller, and less massive than a main-sequence star with a short life time
Compared to a high-luminosity main-sequence star, stars in the upper right of the H-R diagram are
cooler and larger in radius
Compared to a low-luminosity main-sequence star, stars in the lower left of the H-R diagram are
hotter and smaller in radius
Star A appears brighter than star B, as seen from Earth. Therefore, star A must be closer to Earth than star B. T or F
Red giants are very bright because they are extremely hot. T or F
Astronomers can distinguish between main-sequence and giant stars purely by spectroscopic means. T or F
Cool stars can be very luminous if they are very
The mass of a star may be determined
by studying its orbit around a binary companion
What physical property of a star does the spectral type measure?
What can be said with certainty about a red star and a blue star?
blue star is hotter than red star
The stars with masses comparable to our Sun's, but sizes like the Earth are
white dwarfs
On the H-R diagram, the bright blue stars that dominate the naked-eye sky lie
top left
On the H-R diagram, the Sun lies
about the middle of the main sequence
On the H-R diagram, white dwarfs lie Sirius B and Procyon B lie
lower left
On the H-R diagram, red supergiants like Betelguese lie
top right
Binary stars separated enough to be resolved in a telescope are called
visual binaries
The Doppler shift is used to find
spectroscopic binaries
Two stars have the same absolute magnitude, but one lies twice as far from Earth as the other. It will appear half as bright. T or F
The vast majority of stars near us would fall to the bottom right on the H-R diagram. T or F
Most naked-eye stars would fall to the top left on the H-R diagram. T or F
Main sequence stars are fusing hydrogen into helium in their cores. T or F
The mass of a newly formed star will determine its position on the main sequence. T or F
Jupiter's Great Red Spot formed within the last twenty to thirty years. T or F
What is special about Miranda?
It isn't completely differentiated.
Io is the most volcanically active place in the Solar System. T or F
Why does the same side of the Moon always face Earth?
Tidal forces from Earth slowed the Moon's rotation on it's axis.
Which of the following statements is true?
a. The sun appears to rise before it actually reaches the horizon.
b. The Sun appears to set before it actually reaches the horizon.
c. It is completely dark for six months at the North Pole during the winter.
d. All of the above.
e. None of the above.
All wavelengths of electromagnetic radiation travel through vacuum at the same speed. T or F
When compared with lower frequency waves of light, higher frequency waves of light have
shorter wavelengths
Earth's atmosphere is transparent to all wavelengths of EM radiation. T or F
You are emitting all wavelengths of EM radiation right now. T or F
Nathan is four feet away from a light bulb. Jacob is eight feet away from the same bulb. How much brighter is the bulb to Nathan than it is to Jacob?
four times as bright
Most of the stars we see in the sky are
very luminous
The Sun is made of
hydrogen, helium and small amounts of heavier elements
Emission lines are
used to indentify the type of gas giving off the light
On Earth, extended periods of low solar activity correspond to
a cooler climate
We can see the photosphere because
it is the first layer of the Sun in which emitted photons have a chance to leave the Sun
The blackbody radiation from a star can be used to
measure the temperature of the surface of the star
A day on Uranus at the equator (sunrise to sunrise) is the same throughout the year. T or F
All wavelengths of light travel at the same speed in vacuum. T or F
All wavelengths of light carry the same energy. T or F
Nuclear fusion in the Sun converts four protons into a helium nucleus, neutrinos, and leftover particles which are transformed into energy. T or F