Earth Photos From The ISS Are Full of Surprises

One reason I love twitter, tweeting and tweeps is that I learn so much simply by doing something I enjoy. Hardly a day goes by that I don't learn something new. Here is today's discovery.

This morning, Sam Cristoforetti @AstroSamantha, who is currently aboard the International Space Station, tweeted a picture of the Hawaiian Island O'ahu with Honolulu clearly visible.

MT @AstroSamantha: O'ahu island & Honolulu, in beautiful #Hawaii / L'isola di O'ahu con la città di Honolulu, Hawaii pic.twitter.com/6KbZC5C0LU
— Claudia Taake (@ct_la) December 28, 2014

I retweeted this to my own timeline without noticing the odd coloration of the ocean at the top and at the left side of the picture, most likely because I initially saw a small version of it on my phone. 

Shortly thereafter, Frank Benson @mfbenson1 brought up this excellent question:

@ct_la @cirquelar @AstroSamantha what's with all the mud/sediment in the water? Never seen it look like that...
— Frank Benson (@mfbenson1) December 28, 2014

I took a second look at the picture and suggested we might be looking at some very thin, low cloud cover, since mud or sediment don't make much sense, given local geography. Clouds were my best guess, but since I didn't know for sure I included Peter Caltner @PC0101 in the conversation, who is a veritable fount of useful and factual information about pictures of Earth taken from the International Space Station. Turns out Frank and I had both guessed wrong:

@ct_la @mfbenson1 @cirquelar @AstroSamantha That's sunglint, sunlight reflected directly into the camera lens. A purely optical effect.
— Peter Caltner (@PC0101) December 28, 2014

@ct_la @mfbenson1 @cirquelar @AstroSamantha Wave patterns in places may 'break' that reflection directly into the camera, so you have that
— Peter Caltner (@PC0101) December 28, 2014

@ct_la @mfbenson1 @cirquelar @AstroSamantha patch of blue sea in the pic. In an extreme case color photos can look like black/white pix.
— Peter Caltner (@PC0101) December 28, 2014

Peter then tweeted a photo taken from the ISS that shows an example of extreme sun glint, so much so that the brightness 'wipes out' the colors of the land.

Glint off San Remo, Italy, #ISS, Nov 2, 800-mm by @astro_reid @AstroSamantha @silvianalon @eugeniafessia @sweetgazer1 pic.twitter.com/C0RhVfyhTv
— Peter Caltner (@PC0101) November 13, 2014

He added that glint pictures can be extremely useful, since they show coastal inlets and river courses better than aerial views. The ISS orbits at ca. 220 mi (350 km) above Earth.

South-eastern USA in golden sun-glint, from #ISS, Dec 17, 180-mm @TinaMeany pic.twitter.com/c3MXrwEz9p
— Peter Caltner (@PC0101) December 25, 2013

Thanks, Peter, for this really cool lesson in orbital photography effects!