ASTRONOMY 101 EXAM QUESTIONS WITH VERIFIED SOLUTIONS LATEST UPDATE 2026
The arrows in this diagram are meant to show how gravitational equilibrium works in the Sun. What
do the different colors and different arrow lengths represent? - Answers Green arrows represent
gravity; red arrows represent pressure; longer arrows represent a stronger push or pull.
What layer of the Sun are we seeing in this photo? - Answers photosphere
The dark spots in this photo (such as the one indicated by the arrow) represent what we call ___ -
Answers sunspots
Which photo pair shows Earth correctly scaled in comparison to the Sun? - Answers The smallest
speck of the earth
This photograph shows a small portion of the Sun's photosphere. What is going on in the bright
regions (such as the bright region indicated by the arrow)? - Answers Hot gas is rising up from the
solar interior.
his X-ray image shows a loop of hot gas above the surface of the Sun. If we took a visible light photo
that looked in the Sun's photosphere just under the two points where the loop of gas comes down
(arrows), what would we find? - Answers Sunspots
Look again at the loop of hot gas in this X-ray image. Suppose we took another photo looking at the
same place one hour later. What would we see? - Answers The loop would look about the same it
does in the photo (there's like a big red sort of circular loop)
What layer of the Sun are we seeing in this photograph, and in what wavelength band was it
photographed? - Answers Corona, photographed in X-rays
What do the yellow regions represent in this photograph? - Answers Regions where very hot gas is
emitting a lot of X-rays
What do we mean when we say that the Sun is in gravitational equilibrium? - Answers There is a
balance within the Sun between the outward force of gas pressure and the inward force of gravity.
Which of the following best describes why the Sun emits most of its energy in the form of visible
light? - Answers Like all objects, the Sun emits thermal radiation with a spectrum that depends on its
temperature, and the Sun's surface temperature is just right for emitting mostly visible light.
The Sun's average surface (photosphere) temperature is about _ - Answers 5,800 K
What keeps the Sun's outer layers from continuing to fall inward in a gravitational collapse? -
Answers outward pressure due to super-heated gas
Which of the following is the best answer to the question, "Why does the Sun shine?" - Answers As
the Sun was forming, gravitational contraction increased the Sun's temperature until the core became
hot enough for nuclear fusion, which ever since has generated the heat that makes the Sun shine.
What would happen to the core of the sun if its temperature rose slightly? - Answers The rate at
which fusion occurs would increase, leading to an expansion of the core, which would in turn cause
the temperature to drop back down.
Why do sunspots appear dark in pictures of the Sun? - Answers They actually are fairly bright, but
appear dark against the even brighter background of the surrounding photosphere.
Recent claims that global warming is due to changes in solar irradiance related to sunspot activity are
- Answers unlikely since global temperatures have continued to rise even though solar irradiance has
not.
Sunspots are cooler than the surrounding gas in the photosphere because - Answers strong magnetic
fields slow convection and prevent hot plasma from entering the region.
Consider the four stars shown following. Rank the stars based on their surface temperature from
highest to lowest. - Answers Highest temp: a blue white drawf star, sun, orange main sequence star,
and red supergiant star
All stars are born with the same basic composition, yet stars can look quite different from one
another. Which two factors primarily determine the characteristics of a star? - Answers its mass and
its stage of life
According to the inverse square law of light, how will the apparent brightness of an object change if
its distance to us triples? - Answers Its apparent brightness will decrease by a factor of 9.
A star's luminosity depends primarily on its - Answers radius and surface temperature
Which of the following stars are brightest at ultraviolet wavelengths? - Answers O and B stars
If star A is closer to us than star B, then Star A's parallax angle is __ - Answers larger than that of Star
B
The apparent brightness of a star depends only on its luminosity. - Answers False
The arrows in this diagram are meant to show how gravitational equilibrium works in the Sun. What
do the different colors and different arrow lengths represent? - Answers Green arrows represent
gravity; red arrows represent pressure; longer arrows represent a stronger push or pull.
What layer of the Sun are we seeing in this photo? - Answers photosphere
The dark spots in this photo (such as the one indicated by the arrow) represent what we call ___ -
Answers sunspots
Which photo pair shows Earth correctly scaled in comparison to the Sun? - Answers The smallest
speck of the earth
This photograph shows a small portion of the Sun's photosphere. What is going on in the bright
regions (such as the bright region indicated by the arrow)? - Answers Hot gas is rising up from the
solar interior.
his X-ray image shows a loop of hot gas above the surface of the Sun. If we took a visible light photo
that looked in the Sun's photosphere just under the two points where the loop of gas comes down
(arrows), what would we find? - Answers Sunspots
Look again at the loop of hot gas in this X-ray image. Suppose we took another photo looking at the
same place one hour later. What would we see? - Answers The loop would look about the same it
does in the photo (there's like a big red sort of circular loop)
What layer of the Sun are we seeing in this photograph, and in what wavelength band was it
photographed? - Answers Corona, photographed in X-rays
What do the yellow regions represent in this photograph? - Answers Regions where very hot gas is
emitting a lot of X-rays
What do we mean when we say that the Sun is in gravitational equilibrium? - Answers There is a
balance within the Sun between the outward force of gas pressure and the inward force of gravity.
Which of the following best describes why the Sun emits most of its energy in the form of visible
light? - Answers Like all objects, the Sun emits thermal radiation with a spectrum that depends on its
temperature, and the Sun's surface temperature is just right for emitting mostly visible light.
The Sun's average surface (photosphere) temperature is about _ - Answers 5,800 K
What keeps the Sun's outer layers from continuing to fall inward in a gravitational collapse? -
Answers outward pressure due to super-heated gas
Which of the following is the best answer to the question, "Why does the Sun shine?" - Answers As
the Sun was forming, gravitational contraction increased the Sun's temperature until the core became
hot enough for nuclear fusion, which ever since has generated the heat that makes the Sun shine.
What would happen to the core of the sun if its temperature rose slightly? - Answers The rate at
which fusion occurs would increase, leading to an expansion of the core, which would in turn cause
the temperature to drop back down.
Why do sunspots appear dark in pictures of the Sun? - Answers They actually are fairly bright, but
appear dark against the even brighter background of the surrounding photosphere.
Recent claims that global warming is due to changes in solar irradiance related to sunspot activity are
- Answers unlikely since global temperatures have continued to rise even though solar irradiance has
not.
Sunspots are cooler than the surrounding gas in the photosphere because - Answers strong magnetic
fields slow convection and prevent hot plasma from entering the region.
Consider the four stars shown following. Rank the stars based on their surface temperature from
highest to lowest. - Answers Highest temp: a blue white drawf star, sun, orange main sequence star,
and red supergiant star
All stars are born with the same basic composition, yet stars can look quite different from one
another. Which two factors primarily determine the characteristics of a star? - Answers its mass and
its stage of life
According to the inverse square law of light, how will the apparent brightness of an object change if
its distance to us triples? - Answers Its apparent brightness will decrease by a factor of 9.
A star's luminosity depends primarily on its - Answers radius and surface temperature
Which of the following stars are brightest at ultraviolet wavelengths? - Answers O and B stars
If star A is closer to us than star B, then Star A's parallax angle is __ - Answers larger than that of Star
B
The apparent brightness of a star depends only on its luminosity. - Answers False
