THE SOUTHWORTH PLANETARIUM
70 Falmouth Street Portland,Maine 04103
(207) 780-4249 usm.maine.edu/planet
43.6667° N 70.2667° W
Altitude: 10 feet below sea level
Founded January 1970
2021-2022: XII
"It's a small world, but I wouldn't want to have to paint it."
-Steven Wright
THE DAILY ASTRONOME
Friday, September 17, 2021
Quiz 3: Lunar Eclipses
We've devoted the week to lunar eclipses. An inordinate amount of time to some; woefully insufficient to others. To our mind, such celestial spectacles warrant far more than a passing mention. The gradual passage of the lustrous moon into Earth's crimson shadow isn't something one sees every month, let alone every night. Although we no longer ascribe the moon's gradual darkening to the presence of black dragons, the sight still disquiets as much as it captivates: a reminder that powerful celestial forces are at play in the ethereal realm above us. We are also reminded -as though we could forget- of our fleeting mortality. The moon has glided through the planet's shadow millions of times in the past and will continue to do so millions of times more in the future. We are around long enough to behold one or two dozen of those passages. Is that not reason enough to devote so much time to lunar eclipses?
1. When will the next total lunar eclipse occur?
a. November 19, 2021
b. May 15, 2022
c. November 8, 2022
d. March 14, 2025
2. A lunar eclipse can only occur when the moon is ________.
a. at first quarter
b. full
c. at last quarter
d. new
3. A lunar eclipse can only occur when the moon is at or near a ___________.
a. node
b. cusp
c. L-point
d. declination
4. The __________ scale measures a lunar eclipse's color and brightness.
a. Hubble
b. Richter
c. Fujimora
d. Danjon
5. The November 19, 2021 lunar eclipse is a member of Saros Cycle 126. When will the next Saros 126 lunar eclipse occur?
a. November 22, 2028
b. November 26, 2031
c. November 30, 2039
d. December 6, 2042
6. True or false: A solar eclipse will occur either three weeks before or three weeks after a lunar eclipse.
7. A full moon is considered a micro-moon if it is at or near ___________.
a. perigee
b. apogee
c. ascending node
d. descending node
8. The moon is moving away from Earth at the current rate of 4 cm/year. When will lunar eclipses end?
a. 100 million years
b. 600 million years
c. 1.2 billion years
d. none of the above
9. The longest possible total lunar eclipse lasts ____________.
a. 43 minutes
b. 1 hour, 20 minutes
c. 1 hour, 31 minutes
d. 1 hour, 47 minutes
10. A calendar year will at least _______ eclipses (lunar and solar). The maximum number of eclipses in one calendar year is ______.
a.2; 5
b, 4; 5
c. 2; 6
d. 4; 7
ANSWERS
1. When will the next total lunar eclipse occur?
b. May 15, 2022
So, yes, well, this was a bit of a trick question. The November 19, 2021 lunar eclipse isn't total because not all of the moon will pass Earth's umbra. The May 2022 eclipse is total and, weather permitting, we'll be able to see it all!
2. A lunar eclipse can only occur when the moon is ________.
b. full
Only when the moon is full (or at opposition) will it be able to glide through Earth's shadow.
3. A lunar eclipse can only occur when the moon is at or near a ___________.
a. node
A node is an intersection between two orbits. Only when the full moon is at a node will it be aligned with Earth's shadow. Generally, the full moon will pass above or below the shadow and so no eclipse will occur.
4. The __________ scale measures a lunar eclipse's color and brightness.
d. Danjon
The Danjon scale is divided into five levels:- 0 Very dark eclipse. Moon might even not be visible during totality.
- 1 Brown or grey coloration.
- 2 Rust-colored eclipse. Also deep red. Distinct color differential, with the central moon dark and the outer edge brighter and more colorful.
- 3 Brick red eclipse. Yellowish rim around umbral shadow
- 4 Very bright eclipse. Copper red or orange eclipse. Umbral shadow has a bluish edge
5. The November 19, 2021 lunar eclipse is a member of Saros Cycle 126. When will the next Saros 126 lunar eclipse occur?
c. November 30, 2039
Remember that the Saros cycle enables us to predict future eclipses. Successive eclipses within a given Saros are separated by 18 years and 11.3 days. The following Lunar Saros 126 will occur on December 11, 2057.
6. True or false: A solar eclipse will occur either three weeks before or three weeks after a lunar eclipse.
False.
A solar eclipse either follows or precedes a lunar eclipse by two weeks. not three.
7. A full moon is considered a micro-moon if it is at or near ___________.
b. apogee
Apogee is the most distant point in the moon's orbit. A super moon occurs when the full moon is near perigee (the point of least distance).
8. The moon is moving away from Earth at the current rate of 4 cm/year. When will lunar eclipses end?
d. none of the above
Lunar eclipses will continue as long as the Sun continues to fuse hydrogen into helium...about 5 billion more years. Once the Sun expands into a red giant, its outer atmosphere could extend to Earth, causing the moon's orbit to decay down to the Roche limit. At that point, the planet's tidal forces will tear it apart.
Note: In about 1.1 billion years, Earth will be too hot to sustain life due to the Sun's increased energy output. Lunar eclipses will continue, but nobody will remain on Earth to observe them.
9. The longest possible total lunar eclipse lasts ____________.
d. 1 hour, 47 minutes
The greatest amount of time in which the moon can remain entirely within Earth's umbra. The total lunar eclipse that occurred on July 16,2000 was the longest total eclipse in the 20th century. It lasted 1 hour, 46.4 minutes.
10. A calendar year will at least _______ eclipses (lunar and solar). The maximum number of eclipses in one calendar year is ______.
d. 4; 7
We last experienced seven eclipses (4 solar; 3 lunar) in 1982. We will next experience seven eclipses in 2038.
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