Editing Sun (section)

===Exposure to the eye===
[[File:- panoramio (785).jpg|thumb|The Sun seen from Earth, with [[Glare (vision)|glare]] from the lenses. The eye also sees glare when looked towards the Sun directly.|alt=See caption]]

The brightness of the Sun can cause pain from looking at it with the [[naked eye]]; however, doing so for brief periods is not hazardous for normal non-[[Mydriasis|dilated]] eyes.<ref>{{Cite journal |first1=T. J. |last1=White |first2=M. A. |last2=Mainster |first3=P. W. |last3=Wilson |first4=J. H. |last4=Tips |title=Chorioretinal temperature increases from solar observation |journal=[[Bulletin of Mathematical Biophysics]] |volume=33 |issue=1 |pages=1–17 |year=1971 |doi=10.1007/BF02476660 |pmid=5551296}}</ref><ref>{{Cite journal |first1=M. O. M. |last1=Tso |first2=F. G. |last2=La Piana |title=The Human Fovea After Sungazing |journal=Transactions of the American Academy of Ophthalmology and Otolaryngology |year=1975 |volume=79 |pages=OP788–95 |pmid=1209815 |issue=6}}</ref> Looking directly at the Sun, known as [[sungazing]], causes [[phosphene]] visual artefacts and temporary partial blindness. It also delivers about 4&nbsp;milliwatts of sunlight to the retina, slightly heating it and potentially causing damage in eyes that cannot respond properly to the brightness.<ref>{{Cite journal |last1=Hope-Ross |first1=M. W. |title=Ultrastructural findings in solar retinopathy |journal=[[Eye (journal)|Eye]] |volume=7 |issue=4 |year=1993 |doi=10.1038/eye.1993.7 |pmid=8325420 |last2=Mahon |first2=G. J. |last3=Gardiner |first3=T. A. |last4=Archer |first4=D. B. |pages=29–33 |doi-access=free}}</ref><ref>{{Cite journal |title=Solar Retinopathy from Sun-Gazing Under Influence of LSD |last1=Schatz |first1=H. |last2=Mendelblatt |first2=F. |journal=[[British Journal of Ophthalmology]] |volume=57 |issue=4 |year=1973 |doi=10.1136/bjo.57.4.270 |pmid=4707624 |pmc=1214879 |pages=270–273}}</ref> Viewing of the direct Sun with the naked eye can cause UV-induced, sunburn-like lesions on the retina beginning after about 100&nbsp;seconds, particularly under conditions where the UV light from the Sun is intense and well focused.<ref>{{Cite journal |first1=W. T. Jr. |last1=Ham |first2=H. A. |last2=Mueller |first3=D. H. |last3=Sliney |journal=[[Nature (journal)|Nature]] |title=Retinal sensitivity to damage from short wavelength light |volume=260 |issue=5547 |pages=153–155 |year=1976 |doi=10.1038/260153a0 |pmid=815821 |bibcode=1976Natur.260..153H |s2cid=4283242}}</ref><ref>{{Cite book |first1=W. T. Jr. |last1=Ham |first2=H. A. |last2=Mueller |first3=J. J. Jr. |last3=Ruffolo |first4=D. III |last4=Guerry |chapter=Solar Retinopathy as a function of Wavelength: its Significance for Protective Eyewear |title=The Effects of Constant Light on Visual Processes |editor-last=Williams |editor-first=T. P. |editor-last2=Baker |editor-first2=B. N. |publisher=[[Plenum Press]] |pages=319–346 |year=1980 |isbn=978-0-306-40328-6}}</ref>

Viewing the Sun through light-concentrating [[optics]] such as [[binoculars]] may result in permanent damage to the retina without an appropriate filter that blocks UV and substantially dims the sunlight. When using an attenuating filter to view the Sun, the viewer is cautioned to use a filter specifically designed for that use. Some improvised filters that pass UV or [[infrared|IR]] rays, can actually harm the eye at high brightness levels.<ref>{{Cite book |first=T. |last=Kardos |title=Earth science |url=https://books.google.com/books?id=xI6EDV_PRr4C&pg=PT102 |page=87 |publisher=J. W. Walch |year=2003 |isbn=978-0-8251-4500-1 |access-date=22 August 2020}}</ref> Brief glances at the midday Sun through an unfiltered telescope can cause permanent damage.<ref name=Macdonald>{{cite book |last=Macdonald |first=Lee |chapter=Equipment for Observing the Sun |year=2012 |title=How to Observe the Sun Safely |publisher=Springer |place=New York |page=17 |doi=10.1007/978-1-4614-3825-0_2 |quote=Never look directly at the Sun through any form of optical equipment, even for an instant. A brief glimpse of the Sun through a telescope is enough to cause permanent eye damage, or even blindness. Even looking at the Sun with the naked eye for more than a second or two is not safe. Do not assume that it is safe to look at the Sun through a filter, no matter how dark the filter appears to be. |series=Patrick Moore's Practical Astronomy Series |isbn=978-1-4614-3824-3}}</ref>

During sunrise and sunset, sunlight is attenuated because of [[Rayleigh scattering]] and [[Mie theory|Mie scattering]] from a particularly long passage through Earth's atmosphere,<ref name=Haber2005>{{Cite journal |last1=Haber |first1=Jorg |last2=Magnor |first2=Marcus |last3=Seidel |first3=Hans-Peter |title=Physically based Simulation of Twilight Phenomena |year=2005 |journal=ACM Transactions on Graphics |volume=24 |issue=4 |pages=1353–1373 |doi=10.1145/1095878.1095884 |citeseerx=10.1.1.67.2567 |s2cid=2349082}}</ref> and the Sun is sometimes faint enough to be viewed comfortably with the naked eye or safely with optics (provided there is no risk of bright sunlight suddenly appearing through a break between clouds). Hazy conditions, atmospheric dust, and high humidity contribute to this atmospheric attenuation.<ref>{{Cite journal |title=Diurnal asymmetries in global radiation |first=I. G. |last=Piggin |journal=Archiv für Meteorologie, Geophysik und Bioklimatologie, Serie B |year=1972 |volume=20 |issue=1 |doi=10.1007/BF02243313 |pages=41–48 |bibcode=1972AMGBB..20...41P |s2cid=118819800}}</ref>