THE SOUTHWORTH PLANETARIUM
207-780-4249 www.usm.maine.edu/planet
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Altitude: 10 feet below sea level
Founded January 1970
Julian Date: 2459202.16
2020-2021: LXII
THE DAILY ASTRONOMER
Friday, December 17, 2020
Remote Planetarium 135: Final Test I
How much do you remember?
Well, take this test and find out. We started the Remote Planetarium in
late March. Now, in mid-December, the Remote Planetarium is ending.
Before it concludes, we offer a two part Final Test. The questions are
taken directly from past quizzes posted throughout.
Good luck and thank you for participating in the Remote Planetarium on-line
course!
*1. Mintaka, the western most of the three stars forming Orion's belt is
positioned very close to the Celestial Equator. So, Mintaka's declination
would be __________*
a. almost 0 degrees
b. almost 23.5 degrees
c. almost 90 degrees
d. none of the above
*2. . If the moon is 80% illuminated and rises 2.5 hours after sunset, what
is its phase?*
a. waxing crescent
b. waxing gibbous
c. waning gibbous
d. waning crescent
*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. What is an "astronomical unit?"*
a. a unit of measurement equal to Earth's average distance from the Sun
b. a unit of measurement equal to Earth's mass
c. a unit of measurement equal to the Sun's diameter
d. a unit of measurement equal to the moon's average distance from Earth
*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. **How can the Voyager 1 spacecraft continue to travel at a speed of
more than 35,000 miles per hour?*
a. the craft contains an ion propulsion drive
b. the craft's speed is maintained by the radioisotopic
thermoelectric generator
c. it is moving at this speed because it is traveling on its own volition
through the vacuum of outer space
d. it expels gases in one direction which propels it in the opposite
direction
[image: 800px-Cygnus_IAU.svg.png]
Refer to the image above for question # 7
*7. Based ONLY on the information contained within the above image, what
can you conclude about the stars Deneb and Albireo?*
a. Deneb is brighter than Albireo
b. Albireo is closer to us than Deneb
c. Deneb remains above the horizon here longer than Albireo
d. Albireo is west of Deneb
*8.* *Eclipses occur within Saros cycles. The April 8, 2024 eclipse is
part of Saros Cycle 139. When will the next Saros 139 solar eclipse
occur?*
a. April 8, 2034
b. April 11, 2040
c. April 20, 2042
d. May 2, 2060
*9.* * __________ is the largest asteroid in the solar system and was the
first asteroid discovered.*
a. Ceres
b. Vesta
c. Pallas
d. Juno
*10. **The combined mass of all the asteroids in the Main asteroid belt
equals___________*
a. about 3% the moon's mass
b. half the moon's mass
c. twice the moon's mass
d. half Earth's mass
*11.* *What is the difference between a "meteor" and a "meteoroid?"*
a. a meteor is found on the ground; a meteoroid is found in space
b. a meteor is the light produced when a meteoroid infiltrates the
atmosphere
c. a meteorite is found in the air; a meteor is found in space
d. there is no difference between them.
*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. **If a star's temperature doubles, the star's luminosity___________*
a. doubles
b. quadruples
c. increases by eight times its original amount
d. increases by sixteen times its original amount
*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.* *How close is the nearest star system to the Sun?*
a. 4.2 light years
b. 6.7 light years
c. 9.8 light years
d. 12.12 light years
*16. **Wolf 359, Ross 154 and Lalande 21185 are stars named for___________*
a. the name of the astronomers who cataloged those stars
b. the name of the observatories at which those stars were first observed
c. the quadrant of the galaxy in which the stars are located
d. none of the above.
*17.* *What is the "distance modulus?"*
a. the difference between apparent and absolute magnitude
b. the difference between parsec and light year
c. the difference between luminosity and absolute magnitude
d. none of the above
*18. ** Every star begins its life on ________________*
a. the main sequence
b. the asymptotic giant branch
c. in the red dwarf corner
d. at the lower left of the H-R Diagram.
*19. ** Omicron Scorpii's luminosity class is II, meaning that it is a
_____________.*
a. hypergiant
b. subgiant
c. bright giant
d. dwarf
*20.* *The Milky Way Galaxy contains approximately _________ globular
clusters*
a. 50
b. 100
c. 200
d. 1100
*ANSWERS*
*1. * *Mintaka, the western most of the three stars forming Orion's belt is
positioned very close to the Celestial Equator. So, Mintaka's declination
would be __________ *
a. almost 0 degrees
"Declination" is the celestial equivalent to latitude. An object on the
Celestial Equator has a declination of 0 degrees. An object at the north
celestial pole has a declination of 90 degrees. An object at the south
celestial pole has a declination of -90 degrees. In the star chart
below, we can see Mintaka (name not included) just below the celestial
equator. Sirius, the night sky's brightest star, is more than 16 degrees
42 minutes south of the Celestial Equator, so its declination equals -16
degrees 42'
[image: RA-Dec-eq-region-with-coordinates.jpg]
*2. If the moon is 80% illuminated and rises 2.5 hours after sunset, what
is its phase? *
c. waning gibbous
Waning gibbous is the phase that follows the full moon, but precedes the
last quarter moon. Full moon rises around sunset and the last quarter
moon rises around midnight. Waning gibbous is also between 50% - 100%
illumination, not inclusive. So, if the moon is 80% illuminated, it is
gibbous. If it rises after sunset but before midnight, it is waning
gibbous.
*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. What is an "astronomical unit?"*
a. a unit of measurement equal to Earth's average distance from the Sun
[An astronomical unit equals Earth's average distance from the Sun, equal
to approximately 93 million miles.]
*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.* *How can the Voyager 1 spacecraft continue to travel at a speed of
more than 35,000 miles per hour? *
c. it is moving at this speed because it is traveling on its own
volition through the vacuum of outer space
Newton's first law states that "an object remains in a constant state of
motion unless acted upon by an external force." The Voyager 1 craft is
moving on its own volition through the vacuum of outer space. Because
nothing is impeding the Voyager 1 spacecraft it can maintain its motion
indefinitely.
*7. Based ONLY on the information contained within the above image, what
can you conclude about the stars Deneb and Albireo? (Could be more than
one correct answer.)*
a. Deneb is brighter than Albireo
c. Deneb remains above the horizon here longer than Albireo
d. Albireo is west of Deneb
All four of those statements are correct! (At a distance of 380 light
years, Albireo is much closer to us than Deneb, 3200 light years away.)
However, one cannot know their relative distances simply by studying this
image.
- *Deneb is brighter than Albireo*. Yes, Deneb is the constellation's
alpha star. However, based on what we know about the Bayer Nomenclature
System, we cannot be certain that Deneb is the brightest star simply based
on this designation. However, the dot representing Deneb is larger than
the dots marking the other stars within Cygnus. The legend below the image
refers to the magnitudes of the stars. The lower the magnitude (and the
brighter the star), the larger the dot used to represent it. The "Deneb
dot" is larger than the "Albireo dot." Deneb's magnitude is 1.25;
Albireo's magnitude is 3.18.
- *Deneb remains above the horizon here longer than Albireo. *We can
tell that Deneb is north of Albireo because its declination is greater.
Deneb's declination is about 45 degrees. Albireo's declination is about
28 degrees. While both stars will be above our horizon for more than
twelve hours, Deneb remains in the sky for much longer owing to its higher
position.
- *Albireo is west of Deneb *Albireo's right ascension is about 19
hours 30 minutes. Deneb's right ascension is about 20 hours 41 minutes.
As Albireo's right ascension is less than Deneb's, it will be farther to
the west.
8. *Eclipses occur within Saros cycles. The April 8, 2024 eclipse is part
of Saros Cycle 139. When will the next Saros 139 solar eclipse occur? *
c. April 20, 2042
Saros Cycle eclipses occur every 18 years, 11 days and 8 hours apart. We
can use this cycle to help us predict when eclipses will occur within a
given Saros cycle.
The new few solar eclipses in Saros Cycle 139:
*April 30, 2060May 11, 2078May 22, 2096*
Saros Cycles are of finite duration. Saros Cycle 139 started on May 17,
1501 and will end on July 3, 2763
*9. **__**________ is the largest asteroid in the solar system and was the
first asteroid discovered.*
a. Ceres
Giuseppe Piazzi discovered Ceres on January 1, 1801. With a diameter of
939 kilometers, Ceres is the largest asteroid. Of course, it is now known
as a "dwarf planet," as well.
*10. **The combined mass of all the asteroids in the Main asteroid belt
equals___________*
a. about 3% the moon's mass
Some astronomers once wondered if the asteroids were fragments of a planet
that was somehow demolished. This idea is no longer seriously regarded
because we know of no mechanism capable of exploding a planet from the
inside out. Also, the combined mass of all the asteroids is a small
fraction of the moon's mass.
11. * What is the difference between a "meteor" and a "meteoroid?"*
b. a meteor is the light produced when a meteoroid infiltrates the
atmosphere
The three definitions:
- *Meteoroids:* particles in outer space flaked off from comets or
asteroids. These are meteoroids when suspended in outer space.
- *Meteors:* the lights we see when meteoroids infiltrate the upper
atmosphere (between 250,000 - 330,000 feet)
- *Meteorites: *fragments of meteoroids that survived the descent
through the atmosphere and are found on Earth's surface
*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. **If a star's temperature doubles, the star's luminosity___________*
d. increases by sixteen times its original amount
A star's luminosity is proportional to the fourth power of its effective
temperature. If a star's temperature doubles, the luminosity increases
2 x 2 x 2 x 2 = 16 times
*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.* *How close is the nearest star system to the Sun?*
a. 4.2 light years
The nearest star system, Alpha Centauri, consists of three stars. Proxima
Centauri, the closest of these three stars to the Sun, is about 4.2 light
years away. The other two stars, Alpha Centauri A and B are far more
distant, but still part of the same system.
*16*. *Wolf 359, Ross 154 and Lalande 21185 are stars named for___________*
a. the name of the astronomers who cataloged those stars
*17. **What is the "distance modulus?"*
a. the difference between apparent and absolute magnitude
The distance modulus equation * m - M = 5log(d) - 5*
relates apparent magnitude (m), absolute magnitude (M) and the distance(d)
expressed in parsecs. The actual distance modulus is the relation *m -
M. *
*18*. *Every star begins its life on ________________*
a. the main sequence
When a star first becomes active it would be plotted on the H-R Diagram's
main sequence. Once it reaches the next evolutionary stage, it will
migrate off the main sequence toward the right.
*19. **Omicron Scorpii's luminosity class is II, meaning that it is a
_____________.*
c. bright giant
Still highly luminous, but not considered super giants due to their
spectra. Luminosity thousands of times greater than the Sun's.
*20. **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.
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