Looking up the firmament on a starry night, we might see all the stars just in one color – white. But with a telescope or a in a long-time exposure image, you will recognize all the colors of a rainbow. Why is that, you may ask. Well, there are a lots of scientific articles on the web; the easiest explanation for me is that all stars got different temperatures and therefore they glow in different colors. Like really hot ones are blue, colder ones are red. Some say that stars are like a gigantic thermometer, indicating their temperature by colors. Images 1-8 showing the same image but with different tones. Image #3 probably comes to it´s closest what it actually would look like, the others are just an artistic interpretation of mine. Image 9 and 10 are the “Torre Sfinale” in Italy, and image 11 and 12 are “pure” startrail images without a foreground. Especially #11 shows all the colors very nicely. Why is there such a difference in #11 and #12? I´m not sure; the only explanation for me is, that #11 is done at 18mm (focal length) and #12 is done at 10 mm and it might contain therefore more of the Milky Way´s uncountered stars, as you may notify in the 11:00 to 2:30 section. Any other ideas? Trying do to startrail images by yourself? https://wernerpriller.wordpress.com/2011/06/27/startrails/ . Enjoy!
“Begin doing what you want to do now. We are not living in eternity. We have only this moment, sparkling like a star in our hand-and melting like a snowflake…” (Francis Bacon, Sr., English Lawyer and Philosopher, 1561-1626)