endless pursuit

earth_shadow2_crop

In response to Eugi’s weekly prompt “night meets day“:

Night chases day
and day chases night
in endless circles about the Earth –

always pursuing,
and always pursued –
but never catching,
and never touching.

Because between them,
always,
is the twilight –
the penumbra –
that many-hued ribbon
of air-strewn sun-scatter
that is always there,
and always dividing
the shadow of the Earth
from the face that she turns to the sun.

Stand outside at sunset on a clear day, somewhere with a good view to both east and west. The photo below was taken from the escarpment above Lake George – it’s a single panorama shot with labels added but no other editing, even though those trees in the middle like a discontinuity. To the west, the sun drops below the horizon and it is no longer day where you are. To the east is a band of dark blue, quite distinct from the brighter sky above. That dark band is the shadow of the Earth – the night. And, in-between, you stand in a thin band of neither night nor day – penumbra to a physicist, twilight to a poet – that separates the day to the west and the night to the east, so that they can never meet.

earth_shadow_labelled
And this band of twilight only exists because we have an atmosphere that scatters some of the light coming from the sun. It give us a blue sky in the day, and that moving loop of dusk/dawn sky, spinning around the Earth at a thousand miles an hour (literally) that stops the night from ever meeting the day, and the day from ever meeting the night. On planets and moons without atmosphere there is no twilight, and night and day meet at a sharp terminator. 

Our tenuous, fragile layer of air – thin as the skin on an apple – scatters sunlight in front of the onrushing night, and keeps it always just a little behind the day.

20 Comments

Filed under musings, poem

20 responses to “endless pursuit

  1. Delightful piece and I love your comprehensive explanation at the end. I learned something new today! 🙂 Thank you for participating.

  2. Pingback: “Night meets Day” prompt participants – The Bag Lady; anotherkatewilson; RAMBLINGSWITHUSHA – Eugi's Causerie I

  3. Enjoyed reading your poetry and the explanation of ‘night meets day’ below. Was very informative. Thank you.

  4. Usha Paraeswaran

    Thank you for the facts you explained so clearly. The words so apt bringing out the cyclic nature of the phenomenon.

  5. Pingback: Eugi’s Weekly Prompt “Night meets Day” -Roundup – Eugi's Causerie I

  6. How fascinating, Kate! I love your explanation and thank you for the photo with the diagram.

  7. I like how the sequence move to the next. Intricate wordings. Great post !

Comments? Feedback?

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google photo

You are commenting using your Google account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s