THE SOUTHWORTH PLANETARIUM
207-780-4249 www.usm.maine.edu/planet
70 Falmouth Street Portland, Maine 04103
43.6667° N 70.2667° W
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
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
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
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
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
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
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.
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
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'
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.
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, 2060
May 11, 2078
May 22, 2096
May 11, 2078
May 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.
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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