THERE’S SCIENCE IN THE SETTING SUN (1-5): Sunset Colors.
Image Credit & Copyright: Monika Landy-Gyebnar: CLICK photo for larger view and see below for information and related links.
WOW right?! That’s what I was thinking when this photo first came to me. It didn’t take long however, to realize what I was looking at and after reading up a little bit, I determined that the information therein was worth sharing with you.
This photo was taken on April 18, 2011 in Veszprem, Hungary and it’s a sequence of photos of a sunset. As the sun gets closer to the horizon it transitions from a blinding white ball of radiation to something you can almost look at without any protective aid (though I wouldn’t try it). Noticing this, you may ask why that happens in the first place…… Let’s take a closer look.
I think it’s worth noting the obvious right off the bat just to get the juices flowing. The Sun isn’t actually rising or setting; nor does it….ever. Sunsets and sunrises are a product of the Earth’s rotation. The angle of the sunrise or sunset, as well as the length of your days are based upon where you are in the world and what time of year it happens to be. As far as the Sun is concerned its main goal in life is to orbit the galaxy, not to give us an amazing show twice a day, every day that most completely ignore anyway, sadly.
So, the color changes……what’s that all about? When the Sun is overhead around mid-day it is as close to you as it will be all day. Similar to when a superior (outer) planet is at opposition, just on a different scale of course. As the Sun begins to set and regress down toward the horizon it’s also moving further away from you.
Remember, it’s not moving further away from the Earth per-say, it’s moving further away from you and your personal vantage point. Someone else in the world is seeing the Sun directly overhead or they’re seeing a sunrise or even a sunset like you are but because they’re at a different longitude the angle is different. There is actually a great image out there somewhere of two groups of family members, one in Florida and I believe (could be wrong) in Japan and at the same time one was snapping an image of the sunset the other was capturing an image of the sunrise.
For human eye purposes, sunlight reaches us in the form of white light; that white light is made up of 7 primary colors…..Know what they are? How’d you learn it in school? They are; Red, Orange, Yellow, Green, Blue, Indigo (whatever its dark blue) and Violet or “ROY G. BIV” for short. So as the Sun sets and moves further away from you and more importantly, lower on the horizon, that white light that was showering you all day long is now forced to travel through more and more of Earth’s atmosphere due to the angle that it’s passing through. That extra dust, water and particulates in the atmosphere break that white light down into its seven primary colors. Scattered away (via Rayleigh scattering) are the shorter wavelength colors of green, blue, indigo and violet leaving only the longer wavelength red orange and yellow available to reach our eyes. As it sets further, yellow light is then refracted away; then orange until the sun is breaking below the horizon and all we are left with is almost red as it leaves us for the evening.
This is the same process you see taking place if you live in a region where there are often sand or dust storms. The more particulates you place between your eye and the Sun the redder it will appear.
COOL FACT: When you see the sun very low on the horizon to the point where maybe half of it has set already you’re seeing an illusion as the Sun has in fact already set below your horizon. Its light is being bent by refraction in the atmosphere thus showing you what isn’t actually there.
Is there anything else you notice in this photo? That’s right, you may have thought the Sun and Moon because of the atmosphere and Earth’s curvature looked larger on the horizon then when it was higher in the sky. That is in fact not the case as the Sun and Moon are the same size on the horizon as they are in the sky; about one-half of a degree on the sky. This “large horizon” thing is actually known as the “Moon/Sun illusion” and it fools everyone. I’ve actually written on it here so check it out if it interests you: https://danspace77.com/2013/09/15/what-you-see-isnt-always-as-it-appears/
The visible light portion of the electromagnetic spectrum is where the seven ROY G. BIV colors exist and they are in order from shortest to longest wavelengths. Here’s something I’m going to leave you with until the next post. If we go from longest to shortest wavelengths of light in the seven visible colors what color comes after the major sunset colors?……..That’s right, green.
Monika Landy-Gyebnar’s Facebook: https://www.facebook.com/monika.landygyebnar
YouTube channel: http://www.youtube.com/user/nolimetangere67
Earth Science Picture of The Day page for this photo: http://epod.usra.edu/blog/2011/05/color-of-the-setting-sun.html
HyperPhysics Red Sunset/Atmospheric Reddening: http://hyperphysics.phy-astr.gsu.edu/hbase/atmos/redsun.html