File:ESO - Asiago spectra.jpg
Original file (1,089 × 770 pixels, file size: 24 KB, MIME type: image/jpeg)
Summary[edit | edit source]
Comparison between a night sky spectrum obtained in a light polluted site (Asiago Astrophysical Observatory – Italy, upper panel) and a dark site (ESO-Paranal – Chile, lower panel). Spectral line identifications for the main features are traced in red for artificial sources and in blue for the natural ones. The emissions generated by street lighting are clearly visible, mainly in the form of strong lines of Mercury and Sodium, which fall not only in the visible range (500-600nm), but also in the in blue and violet parts of the spectrum.
Licensing[edit | edit source]
| Description |
This image contains a comparison of emission lines from a light polluted site (Asiago Astrophysical Observatory – Italy, upper panel) and a dark site (ESO-Paranal – Chile, lower panel). |
|---|---|
| Source |
The image is from a search of the ESO Public [Public Domain] site, url=http://www.eso.org/public/about-eso/search.html?q=violet&searchthis=Go%21. The source on this site is a pdf file entitled "Where the shadows lie – The dark skies of Chile", url=http://www.eso.org/~fpatat/science/skybright/zenit/zenit_paper.htm |
| Date |
November 2010 |
| Author |
Ferdinando Patat |
| Rationale |
No free use or Public Domain image known to show a comparison of emission lines from a light polluted site (Asiago Astrophysical Observatory – Italy, upper panel) and a dark site (ESO-Paranal – Chile, lower panel). |
| Permission |
Fair use claimed |
This work is copyrighted. The individual who uploaded this work and first used it in an article, as well as subsequent persons who place it into articles, asserts that this qualifies as fair use of the material under United States copyright law.
This template must be accompanied by a {{Non-free media rationale}} justifying the assertion of fair use.
Note: The kinds of things that are considered acceptable for fair use on Wikiversity is significantly less than what is legally permitted. Please consult the Wikimedia Foundation Fair Use Policy to see if this content is permitted on Wikiversity under these further restrictions. Familiarize yourself with the Wikiversity Exemption Doctrine Policy before using this template.
The image is non-free fair use in Violet astronomy.
Fair use for Violet astronomy[edit | edit source]
To illustrate the nature of light pollution emission lines by comparing a light polluted site (Asiago Astrophysical Observatory – Italy, upper panel) with a dark site (ESO-Paranal – Chile, lower panel), since no picture can be obtained of any emission spectrum in visual light itself for the Asiago Astrophysical Observatory.
The image linked here is claimed to be used under fair use as:
- It is a scientifically significant image of the emission spectra of an especially light polluted site for comparison with a dark site.
- It is of much lower resolution than the original (copies made from it will be of very inferior quality).
- The image is only being used for informational/educational purposes.
- Its inclusion in the article adds significantly to the article because it shows the phenomenon depicted in the article and how it has a significant impact on violet astronomy to the general public.
- Not replaceable with a free image since this phenomenon so imaged is rare.
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| Date/Time | Thumbnail | Dimensions | User | Comment | |
|---|---|---|---|---|---|
| current | 20:22, 27 March 2013 | | 1,089 × 770 (24 KB) | Marshallsumter (discuss | contribs) | Comparison between a night sky spectrum obtained in a light polluted site (Asiago Astrophysical Observatory – Italy, upper panel) and a dark site (ESO-Paranal – Chile, lower panel). Spectral line identifications for the main features are traced in ... |
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