Category: Sky

Anatomy of Dawn

Subcategories of Twilight and more

MichaelStephenWills11 Comments

Use your pinky finger to apprehend the sky dome. Imagine yourself at sea, out of sight of land, on a calm day. Keeping your arm extended, place your pinky-tip on the horizon due east, raise your arm directly overhead. The average sized pinky-tip will have spanned 90 of its lengths. The distance measured from the horizon to directly overhead, the zenith, is 90 degrees of sky dome, about one pinky-width per degree, one-fourth of the entire 360 degrees of sky around your spot on the globe.

The apparent width of the sun disk from earth covers 1/2 degree of sky dome. The disk center point moves 15 degrees per hour (360/24 = 15). Using these facts to estimate time to sunset is relatively straightforward. Estimating time to dawn from the sky is more difficult. This graphic, “Twilight-dawn subcategories,” is a way to grasping what happens. Your position on the earth globe affects the experience. For example, at northern latitudes above 60°34′ summer nights never become darker than civil twilight because the sun’s midpoint never drops lower than 6 degrees below the horizon. Civil twilight lasts all night long summer times in parts of Sweden and Finland.

Attribution: “Pmurph5, CC BY-SA 4.0 , via Wikimedia “

The date-time stamp on the first photograph of this series is 6:46:23 am, Cocoa Beach sunrise for February 1st was 7:09:40, 00:23:17, 23.283 minutes in decimal notation, later. This duration divided by 60 minutes in an hour and multiplied by the sun’s apparent velocity across the sky (15 degrees per hour) and minus the .25 degree between sun’s center and disk edge, gives the sun’s center as 5.57 degrees below the horizon: this is a photograph of the sky a minute or so after the sun passed civil dawn into civil twilight. I am not more exact because this calculation does not account the deviation of the sun path from due east at this latitude, lengthening civil twilight duration by almost a minute.

Edge of Civil Twilight: dark clouds soon to take light

The following photograph is time-stamped 7:05:06, 4.567 minutes until sunrise, sun center is just below the horizon, setting the dark clouds of the previous photograph fleetingly on fire.

Civil Twilight at the edge of sunrise

Sunrise has passed in the following photographs, obscured by clouds and making for a great light show. Enjoy!!

References

“Dawn” Wikipedia page, the graphic “Twilight-dawn subcategories,” and the descriptions of subcategories came from this page.

Rosy Fingers of Dawn

Iliad and Odyssey reference for Monday

MichaelStephenWills5 Comments

A portent of new beginnings in an ongoing journey for the last day of February, 2022

…with the “Morning Star” Venus

Above Muirthemne Plain

Romance of Ruins

MichaelStephenWills10 Comments

This series of posts started with “Proleek, Grandfather McCardle’s home” where we explored the site of great grandfather James McCardle’s Proleek farm.  A kilometer from there, at Proleek Dolmen, the ancient portal stones line up to face the plain rising to Slieve Gullion, a name for the mountain taken from the Irish,  Sliabh gCuillinn, meaning “mountain of the steep slope” or Sliabh Cuilinn, “Culann’s mountain.”

There is an connection between Proleek and Slieve Gullion.  Cycles of Irish Myth place a boy named Sétanta living on Muirthemne Plain, of which what we call Proleek Townland was a part.  One day, the king Conchobar was passing his kingdom, Muirthemne, on the way to a feast on the slopes of Slieve Gullion hosted by the blacksmith Culann when he stopped to watch boys playing hurling, Sétanta among them (it is ironic the Proleek Dolmen is surrounded by a golf course in modern times).

Impressed by the Sétanta’s skill, the king invites him to the feast.  Having a game to finish Sétanta promises to follow.  As evening falls the boy approaches the smith’s house to find himself attacked by a huge, aggressive dog.  Acting in the moment, Sétanta dispatches the dog with the hurley and ball he had at hand, driving the ball down the hound’s throat.  (In another version he smashes the hound against a standing stone.)

Feeling Culann mourn the loss of his beloved animal, Sétanta promises to raise and train a guard dog equal to the one he slew.  Until that time he also pledged to guard Culann’s home.  From that time Sétanta was known as “the hound of Cullann”, Cú Chulainn in Irish.

References
Wikipedia articles “Slieve Gullion” “Cú Chulainn” and “Conaille Muirtheimne.”

Venus at dawn

Planet Thoughts

MichaelStephenWills3 Comments

Since 1500 B.C. until today…..

The planet we call Venus has ancient associations with fertility goddesses. The link has persisted at least from the 1600 century B.C. inscribed on Sumerian cuneiform tablets. Three thousand years later the Italian artist Botticelli created in tempura paint on canvas the image of Venus rising from the sea, as the planet Venus does today.

  • “The Birth of Venus” by Sandro Botticelli, c Late 15th century, Public domain, via Wikimedia Commons

Venus Rising

Here is Venus rising from the sea at dawn January 2022, at its brightest and most beautiful. Some mistake this new light in the east for airplane lights; the bright disk of Venus is 25 times brighter than Sirius, enough to cast shadows at night. As Venus proceeds in its orbit, the planet alternately sets after the sun and rises before it, seemingly appearing new each time.

This February I caught a newly risen Venus in this IPhone 7 video, reflected in the waves. It seemed to be a flashing headlight on the beach, the Venus reflection came and went with the passing waves. Venus is the upper, the reflection is beneath. Use the lower right control for the full view.

Looking from his window June 1889, Vincent VanGogh included Venus in his “Starry Night” painting, seen to the right of the Cypress tree.

Detail
“Starry Night” By Vincent van Gogh – bgEuwDxel93-Pg at Google Arts; Culture, Public Domain

Here is a closer view of Venus last January, the planet disk is apparent, unlike even the closest stars, Venus is seen as a whole object. Click on image for a full view.

Venus and Mars

Venus and Mars shared 2022’s pre-dawn winter sky. Click on the first image for a full-size view. Mars is seen above the palm tree stump, on the right. In this photograph, from early February, Venus and Mar apparently moved closer. The closeness is an illusion, the planets are millions of miles apart, on either side of Earth’s orbit. Click on the photograph for a full-size view, Mars can just be made out to the right and above Venus.

Click on image for a full view

This crop clearly shows the brightness of Venus compared to Mars.

Click on image for a full view

Valparaiso Departure III “The Sunset”

The Sun’s Progress

MichaelStephenWills12 Comments

Two minutes after capturing the last light on Concon Point, see “Valparaiso Departure II”, turning the camera 180 degrees, to the south, looking along the Chilean coast, to capture birds on the wing headed toward shore at day’s end.
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Remembering other times,

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waiting for darkness

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with a sky map, studying it to make sense of the stars.

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How far?  How large?

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Light from our star, eight minutes old,

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grazed the earth’s rim the breath of a moth wing ago.

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Connect the dots, stories of heroes, monsters.

Our star, as we know it now

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Singular, alone,

Progress, an illusion to be understood

No less mysterious for that

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Look back to the sheltering headland of Valparaiso, glowing.

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Moll’s Gap on Getty

Happy New Year….starting it off right

MichaelStephenWills12 Comments

We are near Molls Gap on the Ring of Kerry. At our feet is Eric townland, there’s an eponymous Bog Nature Reserve down there. At our feet is Eric townland, there’s an eponymous Bog Nature Reserve down there.

Click me for the two (2) Molls Gap photographs accepted and published by Getty.

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Copyright 2021 Michael Stephen Wills All Rights Reserved

Seven Ladies View Accepted by Getty

My wife, Pam, at Ladies View, on the Ring of Kerry

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Here we are, on the road from Kenmare to Killarney, N71, part of the Ring of Kerry around the Iveragh Peninsula. The view was celebrated by Queen Victoria’s Ladies-in-Waiting during an 1861 tour of Ireland

Click me for the seven (7) Ladies View photographs accepted and published by Getty.

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  • Ladies View, Killarney National Park, Derrycunihy Townland, County Kerry, Republic of Ireland.

Copyright 2021 Michael Stephen Wills All Rights Reserved

Ladies View 10

last version

MichaelStephenWills4 Comments

Here we are, on the road from Kenmare to Killarney, N71, part of the Ring of Kerry around the Iveragh Peninsula. The view was celebrated by Queen Victoria’s Ladies-in-Waiting during an 1861 tour of Ireland

Here the camera, link #9, is turned toward the sun, low in the evening sky, emerging from clouds with a bright sunbeam on Upper Killarney Lake. The previous view was portrait orientation. This is landscape orientation.

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  • Ladies View, Killarney National Park, Derrycunihy Townland, County Kerry, Republic of Ireland.

Copyright 2021 Michael Stephen Wills All Rights Reserved

Ladies View 9

Derrycunihy Townland, County Kerry, Republic of Ireland

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Here we are, on the road from Kenmare to Killarney, N71, part of the Ring of Kerry around the Iveragh Peninsula. The view was celebrated by Queen Victoria’s Ladies-in-Waiting during an 1861 tour of Ireland

Here the camera is turned toward the evening low sun, behind clouds, with subtle light beams. That is Upper Killarney Lake, the Gap of Dunloe behind the far hills.

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Copyright 2021 Michael Stephen Wills All Rights Reserved

Ladies View 8

the penultimate

MichaelStephenWills3 Comments

Here we are, on the road from Kenmare to Killarney, N71, part of the Ring of Kerry around the Iveragh Peninsula. The view was celebrated by Queen Victoria’s Ladies-in-Waiting during an 1861 tour of Ireland

We are almost done with this series….sorry to leave this place.

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  • Ladies View, Killarney National Park, Derrycunihy Townland, County Kerry, Republic of Ireland.

Copyright 2021 Michael Stephen Wills All Rights Reserved