THE SOUTHWORTH PLANETARIUM
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Altitude:  10 feet below sea level
Founded January 1970
Julian Date: 2459072.16
2019-2020:  CXC

THE DAILY ASTRONOMER
Monday, August 10, 2020
Remote Planetarium 78:   First 'Semester' Final Test.

How much do you remember?    We started the "Remote Planetarium" on March
30, 2020 and have covered some ground since then.   We have taken questions
from the previous sixteen tests to create this 'Final examination' for our
first 'semester.'     The Remote Planetarium will continue until December
21, 2020.  On that date we'll post the final lesson in this Remote
Planetarium series.   We will then enjoy our end of the year break and then
the regular Daily Astronomer will return in early  January.    Thank you
for participating in the Remote Planetarium on-line astronomy classes.
 We will begin the second semester on August 31st.

While we don't encourage cheating, you can find an archive of the Remote
Planetarium lessons at this link:
https://lists.maine.edu/cgi-bin/wa?A0=DAILY-ASTRONOMER&X=O0318929354D2E60859&Y=edward.gleason%40maine.edu


Good luck!




*1. What is the Sun's declination on the June solstice?*
a. 0 degrees
b.  23.5 degrees
c.  90 degrees
d  -23.5 degrees

*2. Which of the following constellations are part of the Zodiac?  *
a.   Orion the Hunter
b.   Virgo the Maiden
c.   Taurus the Bull
d.   Pegasus the Winged Horse
e.   Leo the Lion
f.   Gemini the Twins
g.   Perseus the Warrior

*3. The moon's albedo is 0.07.  What does this statement mean?*
a. the moon reflects 7% of the sunlight it receives
b. the moon absorbs 7% of the sunlight it receives
c.  the moon's surface gravity is 7% as strong as Earth's
d.  the moon's diameter is 7% that of Earth

*4. On most days how many tides do we experience each day?*
a.  two high tides; two low tides
b. one high tide; one low tide
c  two high tides; one low tide
d. one high tide;  two low tides

*5. If an inferior planet is at its greatest western elongation, where will
it be visible?*
a.  the eastern pre-dawn sky
b.  the western evening sky
c.  the eastern western sky
d.  it won't be visible at all

*6. The "Fundamental Theorem of Astrophysics" states that*
a.  the chemical composition of stars is unknowable
b.  the laws of physics governing Earth are applicable throughout the
Universe
c.  the Big Bang cannot be precisely modeled
d.  other Universes must exist

*7. ** How many constellations has the International Astronomical Union
officially classified?*
a.  44
b. 66
c. 77
d. 88

*8. ** What's the relation between a solar eclipse and a lunar eclipse?*
a.  a solar eclipse will occur two weeks after a lunar eclipse
b.  a lunar eclipse will occur two weeks after a solar eclipse
c.  a solar eclipse will occur either two weeks before or two weeks after a
lunar eclipse
d.  a lunar eclipse will occur the same week as a solar eclipse

*9. **Long period comets originate in_____________*
a.  the Kuiper Belt
b. the Oort Cloud
c.  the ecliptic
d. the Sagittarius Dwarf

*10. The first Trojan asteroids were discovered traveling along the orbit
of ___________.*
a. Jupiter
b. Saturn
c. Uranus
d. Neptune

*11.* *What is an "astronomical unit?"*
a.  the mean separation distance between Earth and the moon
b.  the mean separation distance between Earth and the Sun
c.  the mean separation distance between Earth and Venus
d.  none of the above

*12.* * Kepler''s Third Law of Planetary Motion states that the square of a
planet's period is proportional to ____________________*
a. the square of its mass
b. the square of its average distance from Earth
c.  the cube of its semi major axis   (average distance from the Sun)
d. its momentum

*13*. *Because the Sun's luminosity will increase throughout its life,
Earth will be rendered inhospitable in approximately____________________*_.
a. half a million years
b. half a billion years
c.  1.1 billion years
d.  5 billion years

*14.*  *The Sun now fuses hydrogen into helium.   Eventually the helium in
its core will be fused into carbon.    When the Sun exhausts its core
helium reserves, what will happen?*
a.  the carbon will fuse into oxygen
b.  the carbon will fuse into silicon
c.  the carbon will fuse into neon
d.  nothing. The Sun isn't massive enough to produce the temperatures
necessary to fuse the carbon into heavier elements

*15.*  *What is the main difference between a refractor telescope and a
reflector telescope?*
a. one can see infrared radiation through a refractor, but not through a
reflector
b. a refractor uses lenses; a reflector uses mirrors
c.  a refractor only allows observers to see planets; a reflector only
allows observers to see stars
d. there is no difference between them

*16. **How were astronomers able to identify the closest stars before they
knew the distances to any of them?*
a.  the closest stars were the brightest stars
b. the closest stars exhibited the highest proper motion
c.  the closest stars were circumpolar
d.  the closest stars were closest to the horizon

*17. **A star's space velocity can be divided into __________ velocity and
_________ velocity.*
a.  right ascension; declination
b.  radial; transverse
c.  sigma; omega
d.  precessional; diurnal

*18.* *A star's spectral type reveals information about ______________*
a. its temperature
b. its chemical composition
c. both a and b
d  neither a nor b
e. none of the above
f.  all of the above.

*19.* *The star Antares' absolute magnitude is -5.28 and its spectral type
is M1.5 .  Where would it appear on the H-R Diagram?*
a.  lower left
b. upper left
c. lower right
d. upper right

*20*.  * Star A is on the main sequence. So, too, is Star B.    Star A is
four times more massive than Star B.   Which of the following statements
about these two stars is/are true?*
a.  Star A is more luminous than Star B
b.  Star A will remain on the main sequence longer than Star B
c.  Star A will remain on the main sequence for less time than Star B
d. none of the above.

*21. **Which one of the following statements about globular clusters is not
true?*
a.   they are only found well outside of the galaxy
b.  they can be billions of years ago
c.  their stars formed around the same time
d.  their stars are metal poor

*22.* *The Milky Way Galaxy contains approximately _________ globular
clusters*
a.  50
b. 100
c. 200
d. 1100

*23. **Why aren't all binary stars eclipsing binaries?*
a. because the star system has to be aligned with Earth in such a way so
that the stars block each other during each revolution.
b. all stars are eclipsing binaries from our perspective.  The brightness
difference is so slight for most of these that we don't notice them.
c. in order to be an eclipsing binary star, the system has to have an
additional component star
d. none of the above.

*24.* *One of the lunar eclipses in Saros Cycle 149 will occur on August
17, 2092.    When will the following Saros 149 lunar eclipse happen?*
a.  August 17, 2099
b.  August 23, 2101
c.  August 26, 2105
d. August 29, 2110

*25. **Why are Type Ia Supernovae useful to determine the distances to
remote celestial objects?*
a.  they are always close
b.  Type Ia supernovae are of equal brightness, in theory
c.  they only appear in nearby galaxies
d. none of the above. Type Ia Supernovae are not actually useful for
distance determination.

*26*. *The declination of Bellatrix is about +6 degrees.  Where in the
world would one NOT be able to ever see Bellatrix?*
a. anywhere north of 84 degrees north latitude
b. anywhere south of 84 degrees south latitude
c. at the north pole
d. at the equator

[image: download.jpg]
*27.  The image above shows an idealized light curve for a transiting
planet.  What does the depth of the lower part of the curve reveal?*
a. the planet's period
b. the planet's size
c. the planet's temperature
d.  the planet's chemical composition

*28. **What is a disadvantage of the transit method of exo-planet
detection?*
a.   it can only find planets around G and K type stars
b.  it can only find planets around stars within 300 parsecs of our solar
system
c.  only a small percentage of stars with planets will be aligned in such a
way as to allow us to observe the transit
d.  the transit method can't enable astronomers to find large planets

*29. **How can astronomers determine the chemical constituents of an
exo-planet's atmosphere?*
a.  they can't.   They can make an educated guess about the chemicals based
on the planet's mass.
b.  the chemicals present in the parent star are always present in the
exo-planet's atmosphere
c.  the star's light passes through the atmosphere, the gases of which
absorb light at different wavelengths.   This spectrum is used to identify
the gases present in the atmosphere.
d. none of the above.

*30.* *Which one of the following is NOT a main type of planet orbit within
a binary star system?*
a. S type
b. P type
c. T type
d. W type

*31. **What is defined as a "habitable zone?" of a star?*
a. a region in which temperatures are neither too high nor too low
b  a region from the star's surface to 100 AU (astronomical units)
c. a region in which water could gather as a liquid on a planet's surface
d.  both a and c
e.  all of the above
f.   none of the above

*32.* *Where is the nearest exo-planet?*
a.  4.2 light years away
b.  8.1 light years away
c.  11.2 light years away
d.  20 light years away

*33.* *Proper stellar motion is affected by all but which one of the
following factors?*
a.  distance
b. transverse velocity
c.  radial velocity
d. absolute magnitude

*34. **How noticeably will the constellation Orion change over your
lifetime, assuming you live to be 100?*
a.  not at all
b. the stars will have shifted about two degrees from their original
positions (on my birth year)
c.  the stars will have shifted between 5 - 7 degrees from their original
positions
d. the constellation will be barely recognizable.






*ANSWERS*

*1. What is the Sun's declination on the June solstice?  *
. b.  23.5 degrees
Declination measures a celestial object's angle relative to the Celestial
equator.     On the June solstice, the Sun reaches its highest altitude of
23.5 degrees north of the Celestial Equator and so its declination measures
23.5 degrees.   On the December solstice, the Sun's declination measures
-23.5 degrees.

*2. Which of the following constellations are part of the Zodiac?    *
b.   Virgo the Maiden
c.   Taurus the Bull
e.   Leo the Lion
f.   Gemini the Twins
The list of Zodiac constellations:
Pisces the Fish, Aries the Ram, Taurus the Bull, Gemini the Twins, Cancer
the Crab, Leo the Lion, Virgo the Maiden, Libra the Scales, Scorpius the
Scorpion, Ophiuchus the Serpent Charmer, Sagittarius the Archer,
Capricornus the Seagoat,  Aquarius the Water Bearer

3.  *The moon's albedo is 0.07.  What does this statement mean? *
 a. the moon reflects 7% of the sunlight it receives
[Albedo measures the ratio of light a body reflects to the light it
receives.   A body with an albedo of 1 reflects all incoming light.  A body
with an albedo of 0 absorbs it all.  We should note that the albedo is
averaged over the entire celestial body.    Some regions reflect more light
than others.    Over all the moon reflects only seven percent of the
sunlight it receives.]

*4. On most days how many tides do we experience each day *
a.  two high tides; two low tides
 [A high tide will occur at your location when the moon is along the
meridian and at the antemeridian, the polar opposite point.  Low tides
occur at your location when you are at right angles from the moon.  See
graphic below:

[image: WPbGj.jpg]
5. * If an inferior planet is at its greatest western elongation, where
will it be visible? *
a.  the eastern pre-dawn sky

   - when a planet is at greatest western elongation, it will be visible in
   the eastern predawn sky.
   - when a planet is at greatest eastern elongation, it will be visible in
   the western evening sky.

*6*. *The "Fundamental Theorem of Astrophysics" states that*
 b.  the laws of physics governing Earth are applicable throughout the
Universe
Astrophysics is only possible because remote physical objects are governed
by the same physical principles that govern objects in our local
neighborhood.

*7. **How many constellations has the International Astronomical Union
officially classified?  *
d. 88
The International Astronomical Union developed a formal listing of these
constellations in 1928 based largely on the work of Belgian astronomer
Eugene Joseph Delaporte (1882-1955)

*8. **What's the relation between a solar eclipse and a lunar eclipse?  *
c.  a solar eclipse will occur either two weeks before or two weeks after a
lunar eclipse
Lunar and solar eclipses can only occur when the moon is at or near a node,
the intersection point between the two orbits.  The moon's orbit contains
two nodes separated by 180 degrees.    The full moon and new moon positions
are also separated by 180 degrees.  So, when a solar eclipse occurs, a
lunar eclipse will have occurred either two weeks before or two weeks after
and vice versa.

*9*. *Long period comets originate in_____________*
b. the Oort Cloud
Long period comets, those with orbital periods exceeding 125 years,
originate in the Oort Cloud: a series of shells enclosing the solar
system.

*10*. *The first Trojan asteroids were discovered traveling along the orbit
of ___________.*
a. Jupiter
Astronomer Max Wolff discovered the first Trojan, 566 Achilles, in 1906.
Trojan asteroids are centered around regions 60 degrees ahead and 60
degrees behind Jupiter's orbit.   These asteroids are named for characters
from the Trojan War that pitted the Greeks against the Trojans.     Trojans
have been found along other planet orbits, as well, including Earth, Venus,
Mars and Uranus.

*11. What is an "astronomical unit?"*
b.  the mean separation distance between Earth and the Sun
This value approximately equals 93 million miles.

*12.  **Kepler''s Third Law of Planetary Motion states that the square of a
planet's period is proportional to ____________________*
c.  the cube of its semi major axis   (average distance from the Sun)
This relation is also known as the "harmonic law."
The square of a planet's orbital period (in years) equals the cube of its
semi major axis (mean distance) in Earth years.

*13*. *Because the Sun's luminosity will increase throughout its life,
Earth will be rendered inhospitable in approximately____________________*_.
c.  1.1 billion years
Even though the Sun's core contains enough hydrogen to sustain the hydrogen
burning reactions for the next five billion years, the Sun's luminosity
will have increased enough so that in 1.1 billion years Earth will become
too hot to harbor life.

*14*. *The Sun now fuses hydrogen into helium.   Eventually the helium in
its core will be fused into carbon.    When the Sun exhausts its core
helium reserves, what will happen?*
d.  nothing. The Sun isn't massive enough to produce the temperatures
necessary to fuse the carbon into heavier elements
After the Sun's helium burning phase ends, it will not be able to produce
the temperatures necessary to fuse carbon into silicon.  The core
thermonuclear fusion reactions will end.

*15*. *What is the main difference between a refractor telescope and a
reflector telescope?*
b. a refractor uses lenses; a reflector uses mirrors
Hence the name reflector.    Reflectors are considered by many to have been
an improvement over the refractors.

16. *How were astronomers able to identify the closest stars before they
knew the distances to any of them?*
b. the closest stars exhibited the highest proper motion
Instead, astronomers correctly assumed that the closest stars would exhibit
the highest proper motions!   All stars move very rapidly.  However, those
closest to us would tend to appear to move more quickly through the sky
than more distant stars.    As an analogy, imagine your watching a car
speed down the freeway.  If you're standing close to the freeway, the car
will appear to move very quickly.   If you're far away from the freeway,
the car will seem to move more slowly across your viewfield.

17. *A star's space velocity can be divided into __________ velocity and
_________ velocity.*
b.  radial; transverse
[image: Proper_motion.jpg]
A star's space velocity is a combination of its radial velocity (the motion
along the sight line) and the transverse velocity (the motion across the
sight line.)    The proper motion is primarily affected by the transverse
motion.

*18.* * A star's spectral type reveals information about ______________*
a. its temperature
b. its chemical composition
A star's spectrum reveals a sequence of absorption lines caused by the
presence of atoms within its outer layers.  These lines are akin to a
barcode that identifies different chemicals within the star.   The spectral
type is also related to the star's effective temperature.   The O stars are
the hottest, while the M stars are the coolest.

*19.* *The star Antares' absolute magnitude is -5.28 and its spectral type
is M1.5 .  Where would it appear on the H-R Diagram?*
d. upper right
As seen below, the star Antares appears at the upper right of the H-R
Diagram.    Antares' spectral type is M1.5, meaning that it is "cool" and
therefore at the right of the H-R Diagram.  With an absolute magnitude of
-5.28, the star is also very luminous and so at the upper region of the H-R
Diagram.
[image: 089dd7456475e0e829408b3696cd8cab.jpg]

*20.* *Star A is on the main sequence. So, too, is Star B.    Star A is
four times more massive than Star B.   Which of the following statements
about these two stars is/are true?*
a.  Star A is more luminous than Star B
c.  Star A will remain on the main sequence for less time than Star B
The mass-luminosity relation tells us that the more massive star will be
more luminous.  Also, the more massive stars have shorter life spans.

*21. **Which one of the following statements about globular clusters is not
true?*
a.   they are only found well outside of the galaxy
Globular clusters congregate within the galactic halo, the spherical region
surrounding the nucleus.

*22*. *The Milky Way Galaxy contains approximately _________ globular
clusters*
c. 200
Galactic star clusters greatly outnumber globular clusters.    Of course,
the total number of stars within all the galaxy's globular clusters vastly
outnumber the total number of stars within all the galactic star clusters.

*23. **Why aren't all binary stars eclipsing binaries?*
a. because the star system has to be aligned with Earth in such a way so
that the stars block each other during each revolution.
More than half of the stars in the sky are systems of two or more stars.
 Those stars will be eclipsing binaries only if they are aligned along our
line of sight.

*24.  **One of the lunar eclipses in Saros Cycle 149 will occur on August
17, 2092.    When will the following Saros 149 lunar eclipse happen?  *
  d. August 29, 2110
Eclipses within the same Saros cycle are separated by 18 years 11 days and
8 hours.

*25. **Why are Type Ia supernovae useful to determine the distances to
remote celestial objects?*
b.  Type Ia supernovae are of equal brightness, in theory
Because Type Ia supernovae occur when the white dwarf's mass exceeds 1.44
solar masses, each one should release the same amount of energy and be of
equal brightness.

*26.* *The declination of Bellatrix is about +6 degrees.  Where in the
world would one NOT be able to ever see Bellatrix?*
b. anywhere south of 84 degrees south latitude
The closer a star appears to the celestial equator, the wider its
visibility region.   Bellatrix is visible in all regions north of 84
degrees south latitude.

*27. **The image above shows an idealized light curve for a transiting
planet.  What does the depth of the lower part of the curve reveal?*
b. the planet's size
The larger the planet, the greater the area it blocks and so the deeper the
curve.

*28.* *What is a disadvantage of the transit method of exo-planet
detection?*
c.  only a small percentage of stars with planets will be aligned in such a
way as to allow us to observe the transit
Fewer than one in a hundred planet systems are aligned with Earth so as to
enable us to observe the star's apparent brightness decrease as a result of
the planetary transit.

*29. * *How can astronomers determine the chemical constituents of an
exo-planet's atmosphere?*
c.  the star's light passes through the atmosphere, the gases of which
absorb light at different wavelengths.   This spectrum is used to identify
the gases present in the atmosphere.
Each molecule absorbs light at specific wavelengths.  By examining the
absorption lines, astronomers can identify the gases present in an
exo-planet's atmosphere.

*30*. *Which one of the following is NOT a main types of planet orbit
within a binary star system?*
d. W type
A planet following an S-type orbit revolves around only one of the stars
within a binary system.    A planet following a P-type orbit revolves
around both stars.  A planet following a T-orbit is located at either one
of the L-points within the orbit of the secondary star.

*31*. *What is defined as a "habitable zone?" of a star?*
a. a region in which temperatures are neither too high nor too low
c. a region in which water could gather as a liquid on a planet's surface
d.  both a and c
The habitable zone is the area around a star which might have conditions
conducive to life's development.   A planet would need to be close enough
to its parent star so as to receive ample heat and light, but not so close
that the temperatures render the planet inhospitable.

*32.**Where is the nearest exo-planet?*
a.  4.2 light years away
Astronomers have found two planets around Proxima Cenaturi, the closest
star to the Sun.  Although one of these planets is within the star's
habitable zone, it is also subjected to strong stellar winds that might
render it inhospitable to life.

*33*. *Proper stellar motion is affected by all but which one of the
following factors?*
d. absolute magnitude
The closer the star, the greater the proper motion.   The proper motion is
a combination of the radial velocity and transverse velocity.

*34*. *How noticeably will the constellation Orion change over your
lifetime, assuming you live to be 100?*
a.  not at all
It is sobering to realize that a constellation will appear exactly the same
on your 100th birthday as it did when you were a newborn.  The stars are
moving quite quickly.  However, they are so far away, the proper stellar
motions are negligible over a human lifetime.


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