1878: Earth Orbital Diagram

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Earth Orbital Diagram
You shouldn't look directly at a partial eclipse because of the damage that can be caused by improperly aligning the solar-lunar orbital plane with the orbital bones around your eye.
Title text: You shouldn't look directly at a partial eclipse because of the damage that can be caused by improperly aligning the solar-lunar orbital plane with the orbital bones around your eye.


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This comic is the third consecutive comic published in the week before the solar eclipse occurring on Monday, August 21, 2017 which is a total solar eclipse and visible in totality within a band across the contiguous United States from west to east. The other comics are 1876: Eclipse Searches and 1877: Eclipse Science.

The comic claims that the reason that eclipses don't happen every month is simple to understand by looking at an orbital diagram. Ironically, the cartoon has so many parts and labels which make it far more difficult to understand than is implied. While the graph itself is based astronomical definitions all the labels are nonsense in this context.

All these labels are complicated words, some are somewhat related to orbital mechanics ("equinox", "perihelion") while some are just latin sounding nouns. Moreover, many of the labels provided are kludged, obfuscated, or simply made up. Compare/contrast with the standard Kepler Orbit diagram. Most easily recognizable are the "Dimples of Venus," referring to axis-intersection points in the diagram on Earth.

The reason why eclipses do not occur every month is because the Moon and Earth do not orbit on a single plane; the moon's orbit has an angle, or inclination of about 5.145 degrees relative to the ecliptic plane and therefore only rarely passes directly between the Earth and the Sun. This fact is evident from this diagram and is correctly labelled with a symbol that looks like the Greek letter "phi" with two bars; the remaining labels do not contribute to this explanation and exist only to distract or misinform the reader.

The title text refers to 'orbit' being also the anatomical term for the eyesocket.

Word used in the comics Meaning of word used Actual astronomical term Meaning of actual term
Astral plane A plane of existence in various esoteric theories. Also used in fictional fantasy context.
Declension Inflection of nouns in a language. Inclination The "tilt" of an orbit
Hypothecate A legal verb that means something similar to "make a mortgage"
Perihelix Portmanteau of helix and perihelion Perihelion Lowest point in a solar orbit
Prolapse A medical condition
Sagittal plane Anatomical plane, dividing the body in left and right. Orbital plane The plane in which heavy object and orbiting object (in this case earth and sun) lie.
Sagittal plane A vertical plane that divides the human body into left and right sides Ecliptic plane Plane in of the Earth's orbit
Solar plexus Network of nerves located in the abdomen. Sun Star in our solar system.


Ambox notice.png This transcript is incomplete. Please help editing it! Thanks.
[An orbital map of the Earth is shown. The Sun is in the center, the Earth is at the right bottom, and the Moon is left below the Earth.]
Why isn't there an eclipse every month?
This is a common question! The answer is made clear b a quick look at the Earth's orbital diagram:
[Label Sun:]
Solar plexus
[Label on the Earth's plane:]
Sagittal plane
[Labels Earth's orbit (beginning at the Earth counter clockwise):]
Perihelix, Declension, Obsequity, Hypothecate, Enceliopsip, Equinox (Solstice in British English)
[Two angles in the plane are labeled as:]
Determinant of the date of Easter, Arctangent
[The plane of the Moon is pictured in a small angel to the Earth's plane and named Astral Plane. The angel is presented between to lines (Greek Nu or Gamma and a double Greek Chi) and named by a fictional character similar to a Greek Phi but with two vertical lines.]
[The labels at the Moons path are:]
Tropopause, Prolapse, Errata.
[An arrow points to the Earth at the zero meridian on the equator. The label reads:]
Dimples of Venus

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I guess first off, we should note the "solstice" is *not* the Bristish equivalent of "equinox" -- they are actually opposites. The equinoxes occur in April and September, when the day & night are equal length, and the solstices occur in June and December, when the length of daylight and nightime, respectively, are at their longest. JamesCurran (talk) 15:30, 18 August 2017 (UTC)

Technically, the opposite of solstice is the other solstice. Solstice and equinoxes are orthogonal. -- Hkmaly (talk) 00:01, 20 August 2017 (UTC)

Being picky but the Equinox/Solstice section refers to equinoxes marking the start of either spring or autumn, but actually both equinoxes mark the beginning of both spring and autumn in opposite hemispheres. ExternalMonolog (talk) 22:08, 22 August 2017 (UTC)

"Determinant of the date of Easter" refers to the fact that in the Catholic Church (and possibly other Christian denomiations) the date of Easter is the first Sunday after the first full moon of Spring, which means it is an astronomical calculation, but completely unrelated to the indicated angle. JamesCurran (talk) 16:28, 18 August 2017 (UTC)

Well, everyone celebrates Easter on the same day, right? So it's the first Sunday after the first full moon for everybody. Berets (talk) 23:20, 18 August 2017 (UTC)
No, not all denominations agree on the date of Easter; a particular example being the Orthodox church, which usually has Easter a week after the Catholic church, but sometimes as much as five weeks later. The difference is caused by the two denominations using different idealized calendars, both lunar and solar, as well as a slight difference in the definition. 18:41, 19 August 2017 (UTC)

"Astral planes" might as well be a Unicode reference, taking into account Randall's occasional mention of emoji, since emoji reside on one of the astral planes: https://en.wikipedia.org/wiki/Plane_%28Unicode%29 (talk) (please sign your comments with ~~~~)

That supplementary planes humorously refer also to Astral planes as mentioned in this explanation.--Dgbrt (talk) 19:54, 18 August 2017 (UTC)

Solstice comes from the Latin ... Sol = Sun .. Sistere = Stand still. It literally means the day the sun stands still and refers to the longest day of the year (summer) and the shortest day of the year (winter). So how does the Sun "stand still". On those days the Earth reaches either end of orbital ellipse and returns around the other side. If you stick a pole in the ground and observe its shadow every day at Noon you will see the shadow grow longer every day from winter to summer and grow shorter every day from summer to winter. The shadow is shortest when the Sun is highest in the sky at mid-summer and the shadow is longest when the sun is lowest in the sky at mid-winter. The sun is either getting higher in the sky or lower in the sky every day. When the Earth is at the end of the ellipse and the transition takes place the shadow will not make any noticeable change from one day to the next and one could say that the "Sun has stood still". Rtanenbaum (talk) 19:36, 18 August 2017 (UTC)

I think that Solstice/Equinox thing is a reference to Randall having a hobby of spreading linguistic misinformation, as seen in 1677:Contrails. 00:32, 19 August 2017 (UTC)

I'm not sure what the labels of the planes are, but they certainly aren't Greek letters. They look like alchemical symbols to me. 00:56, 20 August 2017 (UTC)

Part of the humor of Declension is that it's a portmanteau of right ascension and declination. Right now only declination is mentioned. 02:43, 20 August 2017 (UTC)

Arctangent is also a music festival in the UK, happening when this comic came out. -- 22:30, 21 August 2017 (UTC)