APOD: Equinox: The Sun from Solstice to... (2012 Sep 23)

[APOD Robot]

Equinox: The Sun from Solstice to Solstice

Explanation: Yesterday was an equinox, a date when day and night are equal. Today, and every day until the next equinox, the night will be longer than the day in Earth's northern hemisphere, and the day will be longer than the night in Earth's southern hemisphere. An equinox occurs midway between the two solstices, when the days and nights are the least equal. The picture is a composite of hourly images taken of the Sun above Bursa, Turkey on key days from solstice to equinox to solstice. The bottom Sun band was taken during the winter solstice in 2007 December, when the Sun could not rise very high in the sky nor stay above the horizon very long. This lack of Sun caused winter. The top Sun band was taken during the summer solstice in 2008 June, when the Sun rose highest in the sky and stayed above the horizon for more than 12 hours. This abundance of Sun caused summer. The middle band was taken during the Vernal Equinox in 2008 March, but it is the same sun band that Earthlings saw yesterday, the day of the Autumnal Equinox.

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[trucker743]

Why do the suns in the Solstice bands appear pinker than the ones in the Equinox band?

[Ally]

Interesting format. Bursa is 40deg N. It would be interesting to see how the same format would appear for my location - Aberdeen Scotland - 57deg N

[bjmb]

"Yesterday was an equinox, a date when day and night are equal." that is not true, yesterday the day was everywhere on earth a bit or a lot longer than the night, on both poles there was midnight sun

[canopia]

Why do the suns in the Solstice bands appear pinker than the ones in the Equinox band?

Actually the Sun images in Equinox band are bluer than normal, as the sky on that day was hazy and there were passing high clouds from time to time.

Interesting format. Bursa is 40deg N. It would be interesting to see how the same format would appear for my location - Aberdeen Scotland - 57deg N

I actually started shooting a 30d N version when I was working in Libya. I was able to shoot the winter solstice series in December 2010, but then you know what happened in the country. I would also like to see similar pictures shot in different latitudes.

Tunç Tezel

[Moonlady]

Very interesting image from Solstice. Looks like a big smiley

[moonstruck]

That is soo cool.......thanks Tunc

[moonOmoon]

pretty lame eqinox and analemma

[Boomer12k]

Good explanation of Winter and Summer....the lack of, or profuse-ness of, Solar Energy.


Why do I suddenly feel like a FISH????


:---[===]*

[Ann]

Congratulations on your APOD, Tunç Tezel. You are one of the great photographers here!

Ann

[bystander]

This is a repeat of APOD: 2008 Sep 22, http://asterisk.apod.com/viewtopic.php?t=14481

[BillBixby]

Love the APOD pic. Guess beauty is in the eye of the beholder as my eye seems to be viewing an entirely different picture as moonOmoon. Based on the caption of the APOD I expected to see a pic similar to the pic from the day before. Very pleasantly surprised to find an entirely different rendering of the event.

If anybody happens to read this post and can explain the picture moonOmoon has posted in his comment, I would appreciate it. Currently I am totally baffled by it, but find it cute. Reminds me of one of the characters from one of the Star Wars films.

(I think this is my third post to Asterisk. My first post was as BrovoBrovo which is military for my initials [BB]).

[geckzilla]

It's a llama. Analemma, llama... get it? har har har. He didn't appreciate the photos so he posted a picture of a llama with a bad underbite and a funny haircut.

[bystander]

It's a llama. Analemma, llama... get it? har har har. He didn't appreciate the photos so he posted a picture of a llama with a bad underbite and a funny haircut.

But the APOD wasn't an analemma, nor was it supposed to be.

[BillBixby]

Thank you, both, for the reply's. I was too blinded by the light pollution in the darkness of my mind to see the answer without help.

Bill

[geckzilla]

It's a llama. Analemma, llama... get it? har har har. He didn't appreciate the photos so he posted a picture of a llama with a bad underbite and a funny haircut.

But the APOD wasn't an analemma, nor was it supposed to be.

Yeah, but his comment was regarding both yesterday's analemma and today's non analemma.

[neufer]

It's a llama. Analemma, llama... get it? har har har.

He didn't appreciate the photos so he posted a picture of a llama with a bad underbite and a funny haircut.

The bad under-bite presumably emulating the solar paths.

Anna Llama.... any relation to Eta Careninae?

Click to play embedded YouTube video.

Click to play embedded YouTube video.

[flash]

...
This lack of Sun caused winter.
...
This abundance of Sun caused summer.
...

No doubt the duty cycle of the sun is important in causing winter and summer, but also important is the difference in angle of incidence of sunlight. In the winter, not only is the sun visible for less time each day, but also the angle of incidence is lower, resulting in the (nearly same) energy provided being spread over a greater surface area. This effect is further enhanced by the increased reflection from such a lower angle of incidence. Further enhancement comes from the increased refectivity of snow.

Offsetting these effects (at least in the northern hemisphere) is the fact that the Earth is closer to the Sun in the northern winter, thereby increasing the energy contained in the incident radiation. In the southern hemisphere the effect is opposite.

[neufer]

...
This lack of Sun caused winter.
...
This abundance of Sun caused summer.
...

No doubt the duty cycle of the sun is important in causing winter and summer, but also important is the difference in angle of incidence of sunlight. In the winter, not only is the sun visible for less time each day, but also the angle of incidence is lower, resulting in the (nearly same) energy provided being spread over a greater surface area.

I really think Otto covered that (inelegantly perhaps?) in his lack of sun(light) statement:

...in 2007 December, when the Sun could not rise very high in the sky nor stay above the horizon very long.

This effect is further enhanced by the increased reflection from such a lower angle of incidence.

There is certainly increased reflection off of water & clouds; although this effect is seldom explicitly stated.

[neufer]

On the Equinox the sun rises due east and sets due west everywhere.

And at the Equator the sun rises & sets

• ε degrees to the north on summer Solstice and
  ε degrees to the south on winter Solstice
  where ε is the axial tilt or obliquity (= 23.43929°).

But where does the sun rise & set on the Solstice at other latitudes

And, in particular, where does the sun rise & set on the Solstice at Bursa (40°11′N)?

cos(azimuth) = sin(ε)/cos(latitude)

For Bursa:

• cos(58.62°) = sin(23.43929°)/cos(40°11′)

At Bursa the sun rises & sets:

• 31.38° to the north on summer Solstice and
  31.38° to the south on winter Solstice.