Penelope: All because of her?
One could argue that Penelope, and not her more famous cousin Helen, caused the Trojan War. While one might think this assertion requires a taffy stretch of logic, let's quickly consider the circumstances which precipitated that great conflict. First, we know all the gods and goddesses except Eris, the goddess of discord, gathered to celebrate the marriage of Peleus and Thetis. The divinities wisely excluded Eris because, well, she was the goddess of discord. She avenged this slight by tossing an apple into the wedding party. It was gold coated and bore the label, "for the fairest." Hera, Athena and Aphrodite -the three most powerful goddesses- all sought to claim it. Initially, they asked Zeus to decide which of them would receive the coveted apple. He wisely deferred the judgement to Paris, a Trojan price. Each goddess offered Paris a bribe to influence his decision. He selected Aphrodite to receive the apple as she offered him the world's most beautiful woman, Helen, then married to Spartan king Menelaus. Paris then conspired with Aphrodite to kidnap Helen and bring her back to Troy. This abduction prompted the Greeks to gather an immense armada (the thousand ships) that sailed to Troy to regain her. Yet, one must wonder about that mobilization. Why did so many of them bother to sacrifice life, limb, comfort and leisure just to preserve a single marriage? We can ascribe their actions to the brilliantly cunning Odysseus of Odyssey fame. Years earlier nearly every Greek man had gathered at King Tyndaraeus' palace in the hope of marrying his step daughter Helen. (Zeus had sired Helen on the King's wife Leda, whom he seduced in the form of a swan. Tyndareus raised her as though she were his own.) Tyndareus withheld his decision for he feared that it would induce the legions of disappointed suitors to commit violence against the chosen man. He confided his anxiety to Odysseus who had been among the throng laying siege to the palace. Tyndareus was wise for having done so since Odysseus was the only one present who didn't seek Helen. He much preferred her cousin Penelope, daughter of the King's brother Icarius. Odysseus told Tyndareus that he could offer a solution to the problem if Tyndareus would persuade his brother to choose Odysseus as Penelope's husband. Tyndareus readily agreed. Odysseus instructed him to make all those present swear a solemn oath to protect the sanctity of Helen's marriage no matter who he chose to be her husband. The King did exactly as Odysseus suggested. Every suitor took the vow readily, for he hoped he would be the chosen one. So, after Tyndareus selected Menealaus, all the other suitors were oath-bound to not only offer no violence, but to also defend the marriage against any interference. The suitors were therefore compelled by oath to launch an assault on Troy following Helen's abduction. If Odysseus had not longed for Penelope, he might not have devised such a scheme. The rejected suitors would not have then been oath-bound to attack Troy and the Trojan War would not have even occurred. Of course, one could also assign blame to: Odysseus for conceiving of the accursed idea; Aphrodite for not offering the most beautiful unmarried woman; Paris for not thinking with his brain; Zeus for not adjudicating the matter himself; or Eris for starting the whole chain of unfortunate events.
Ironically, when the Greek forces mobilized for the assault Odysseus did not want to join them. He was loath to leave his wife Penelope and their newborn son Telemachus. When fellow Greek Palamedes traveled to Ithaca to collect Odysseus, the latter pretended to be mad. He spoke loudly and incoherently while plowing salt into his soil. Suspecting chicanery, Palamedes placed Telemachus within the plow's path. Though still babbling, Odysseus diverted the plow away from his son thereby revealing his attempted deception. Miserably, Odysseus then consented to participate. He was gone for twenty years; ten during the Trojan War and another ten during his long voyage back to Ithaca. During that prolonged absence, Penelope remained steadfastly faithful. After the war ended, many of the surviving Greek warriors returned home and sought Penelope's hand in marriage. (Helen had been reunited with Menaleus.) Penelope refused them all, insisting that Odysseus still lived despite the delay in his return. Eventually so much time elapsed that all the men assumed Odysseus had to have perished during his return voyage. Many of the Greeks then not only renewed their efforts, but remained at Odysseus' estate eating his food and essentially living on his wealth. Penelope assured them she would choose a suitor as soon as she completed a funeral shroud for her father-in-law Laertes. She worked on it assiduously each day, but then secretly undid the work at night so that she would never complete it. This ruse worked for three years until her treacherous servant Melantho revealed the trick to all the suitors. Penelope then stood before them, confessed the deception and said she would marry whoever could string Odysseus' bow and fire an arrow through the gaps of twelve ax heads bound together. All the suitors tried and failed miserably. None of them could even so much as string the bow. Then, a strange old beggar emerged from the crowd and asked for a chance to pass her test. Penelope was amused while granting his request, but unamused when he managed to string the bow and send it flying cleanly through the ax heads. The old man then removed his disguise and they all saw the beggar was Odysseus, himself. Telemachus, then a young man, ran forth to join his father. They then slew as many suitors as they could. Only those who were sufficiently swift escaped with their lives. After the fight, Odysseus explained to his wife that he had arrived incognito in order to observe her behaviour and determine if she had remained faithful. Only when he was convinced of her fidelity did he come forward to accept the arrow challenge and then reveal his true identity. However, Penelope was suspicious, for she hadn't seen her husband for twenty years and believed that the man before her could have been an impostor. She, being as cunning as Odysseus, then ordered her servants to fetch their bed and bring it to her. Odysseus was incensed. "One of our bedposts is a live olive tree," he said harshly. "How can the bed be moved?!" Penelope then realized that the man was indeed her husband and welcomed him gladly.
Although Helen was more widely celebrated than her cousin, Penelope is considered the more admirable of the two by virtue of her fidelity. (It is a matter of debate whether Helen was truly abducted or went away with Paris of her own accord.) Even today the name "Penelope" is sometimes used in reference to a wife who remains faithful to a long absent husband. We know of no equivalent name to denote a husband faithful to an absent wife simply because mythology provides us with no namesake character.
THE SOUTHWORTH PLANETARIUM
70 Falmouth Street Portland, Maine 04103
43.6667° N 70.2667° W
Altitude: 10 feet below sea level
Founded January 1970
Julian Date: 245966.16
2019-2020: CXXXIV
Good morning and happy Monday!
Yes, during today's excursion into the wild black yonder we're going to continue our discussion about lunar eclipses. Let's quickly review some of what we've already learned about them.
Lunar eclipses occur when the full moon moves through Earth's shadow. We recognize three lunar eclipse types:
- Total lunar eclipses occur when the moon moves entirely into the umbra, the inner part of Earth's shadow.
- Partial lunar eclipses occur when the moon moves partially through the umbra
- Penumbral lunar eclipses occur when the moon only moves through the penumbra, the outer part of Earth's shadow.
A lunar eclipse is always associated with a solar eclipse that occurs either two weeks before or two weeks after.
As is true with every solar eclipse, each lunar eclipse is part of a Saros cycle. Lunar eclipses within a given Saros recur every 18 years and 11 days.
We now continue with the lunar eclipse chart reading.
If the image below is too small, I have attached a larger image on our web-site:
We'll continue working down through the chart featured above.
To the upper left and right of the central moon passage diagram one finds information pertaining to the Sun and moon, respectively. "Geocentric coordinates" refers to the coordinates of the Sun and moon relative to an observer at Earth's center. Yes, Monsieur Verne, there probably aren't any. However, these coordinates enable astronomers to determine the coordinates suitable for any given location, called "topocentric." These coordinates are valid only at the moment of greatest eclipse, when the moon's center is at a minimum distance from the center of Earth's shadow.
- RA: the right ascension of the body. This value measures the angular distance from the vernal equinox measured in hours, minutes and seconds
- DEC: the declination of the body. This value measures the angular distance from the celestial equator. Note that the Sun is almost 20 degrees north of the celestial equator, close to its maximum angle of 23.5 degrees. We should expect the Sun's declination to be so high in late May
Why aren't the RA and Dec values for the Sun and moon the same at greatest eclipse? Because those coordinates refer to the center points of both bodies. These values would only be equal if the moon's center intersected precisely with the umbra shadow's center.
- SD: Semi diameter. Half of the body's angular diameter. We remember that the moon and Sun occupy approximately one half a degree (30 arc minutes) from our perspective.
- HP: Horizontal Parallax the apparent difference between a body's apparent and actual position on the horizon. This parallax is maximum on the horizon and at minimum at the zenith (the point directly overhead.)
MOON PASSAGE DIAGRAM
We can use this diagram and our knowledge about Saros cycle numbering to determine the date of the next lunar eclipse and its duration relative to this event. Eclipses occur when the moon is at or near a node, the intersection between both Earth's orbit and the moons. We divide these nodes into two types: descending and ascending.
When the moon crosses the descending node, it is moving south of Earth's orbital plane. When the moon crosses the ascending node, it is moving north of it.
- Odd numbered Lunar Saros eclipses occur at the descending node
- Even numbered Lunar Saros eclipses occur at the ascending node
The 16 May 2022 lunar eclipse is part of Saros number 131. These eclipses occur at the descending node. This information is quite helpful because each successive lunar eclipse in the Saros 131 series will be slightly "higher" than the one preceding it. The very first 131 Saros eclipse was a penumbral eclipse that occurred on May 10, 1427. During this event, the moon passed slightly into the southern most part of Earth's penumbra. The moon moved slightly higher into the penumbra during the next 131 eclipse (May 21, 1455). The moon passage diagram shows the moon's upper limb intersecting the central line traversing Earth's umbra. We know that since the Saros 131 eclipses occur the descending node, the next 131 eclipse should be "higher." As, indeed, it is:
26 May 2040 lunar eclipse (Saros 131)
The next 131 lunar eclipse brings the moon closer to the central part of Earth's umbra.
As an exercise, let's approximate when the following 131 lunar eclipse will happen and also determine if the moon will move closer to the shadow center during that eclipse.
The eclipse date will be 6 June 2058
We see that the moon is even closer to the shadow center than the previous eclipse, as we should expect. The following Saros 131 lunar eclipse happens on June 17, 2076 and the next on June 28, 2094. The 2094 eclipse will be the longest duration eclipse of the 131 cycle. Totality will last 102 minutes. Subsequent Saros 131 lunar eclipses will then shift the moon away from the center, each one progressively higher than the previous event. During the final Saros 131 lunar eclipse on July 7, 2707, the moon will slide along the upper penumbral rim.
Note: Even numbered Saros cycle lunar eclipse begin at the ascending node. During the first eclipse of an even numbered Saros, the moon will move along the upper penumbral limb. During the last eclipse, it will slide along the lower penumbral limb.
At the lower left of the diagram we see the eclipse durations.
- The entire eclipse lasts 5 hours, 18 minutes and 40 seconds: the time period separating the moon's first and last contact with the penumbra.
- The umbral eclipse lasts 3 hours, 27 minutes and 14 seconds. During this phase, the moon is either partially or wholly within the umbra.
- The total eclipse lasts 1 hour, 24 minutes and 53 seconds. This is the time when the moon is completely within the umbra, the phase known as totality.
Finally, we have the world visibility map.
Where in the world will the eclipse be visible, not visible or partially visible.
- Observers within the darkest region (e.g. Australia, most of Asia and Alaska) won't observe any of the eclipse simply because the moon won't be above the horizon in those areas
- Observers within the white region (e.g. eastern US, South America) will be able to see all of the eclipse.
How much the other observers see depends on their locations. We'll move along the map from right to left If you're an observer within the band between:
- P1 and U1: the penumbral eclipse will be in progress when the moon sets. You won't see much of anything
- U1 and U2: the umbral eclipse will be in progress when the moon sets. You will start to see the dark shadow moving across the moon. The closer you are to the U2 line, the larger the shadow will appear when it sets
- U2 and U3: the eclipse will be total when the moon sets.
- U3 and U4: totality will have ended by the time the moon sets. You will see the moon moving out of the umbra as it sets
- U4 and P4: the moon will have completely left the umbra by the time it sets. You will miss part of the penumbral eclipse: i.e. you won't miss anything at all.
- P1 and U1: the moon will be moving into the penumbra when it rises. You won't miss anything at all
- U1 and U2: the moon will be moving into the umbra when it rises.
- U2 and U3: the moon will be entirely in the umbra when it rises. Totality will be in progress
- U3 and U4: the moon will have started leaving the umbra when it rises. You will have missed totality.
- U4 and P4: the moon will have left the umbra entirely by the time it rises. You will have missed it, I'm afraid
Tomorrow, we infiltrate the realm of comets and asteroids.
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