Have you ever noticed that while walking at night and you look up the streetlight that there appears to be a somewhat colored ring around the light? Or have you ever noticed this same kind of ring around the sun and moon? Better yet, have you ever seen this similar ring very much emphasized during a solar eclipse? These rings are known as coronas. However, there is a key difference in how these coronas are visible.
Solar and lunar coronas (halos around the sun and moon) are illuminated by three sources, the K-corona, the F-corona, and the E-corona. The K-corona is created by sunlight scattering off of free electrons. The F-corona is visible due to sunlight bouncing off of particles. These electrons and particles are located within the magnetic field of the sun and moon. The E-corona visibility is apparent due to spectral emissions produced by ions in the coronal plasma. These three combinations form the corona in which we see from.
If you were walk by a frosty store's window on a cold night, you may notice that there are coronas surrounding the interior light. There are two causes of diffraction of light that occurs here. The frozen water drops on the window are fairly uniform and flat, and when light passes through the frost it is diffracted. The corona also results from the diffraction of light around small objects which are about a wavelength of visible length in size. The streetlight corona is similar to the other coronas I've discussed except for one key factor. With the streetlight corona, the small objects which are about a wavelength of visible length in size actually occur within your eye! These diffracting units are from mucus particles on the corneal surface and radial fibers in the crystalline lens. It makes sense that such responses occur in this portion of the eye. The lens fulfills the function of altering the refractive index of light entering the eye to focus on the retina (Forrester, Dick, McMenamin, Roberts, 2008). The cornea itself also possesses refractive abilities, which are of greater power than the lens. The observed corona is often defined as an entoptic halo, meaning perceptions of light falling on the eye and rendering objects visible within itself.
Thus, the streetlight corona is a product of your own doing, as opposed to the plasma atmosphere that surrounds celestial bodies. This can be shown by blocking out the moon at nighttime with your thumb. The halo effect of the moon can still be seen. This would not be the case if you were to block out the streetlight, as the halo effect would not be visible. Corona's created by the sun and moon have physical properties that create them, whereas streetlight coronas are created by the human eye.
I found this to be a very informative and useful website, due to it's easy access and informational content. It contains a large scope of both facts and theories involving physical features of coronas, variability of the corona, the Stellar Coronae, the physics of the corona (seemingly appropriate for this class), and coronal heating problems. It helped me compose my answer because I used it to explain the three sources that illuminate solar and lunar coronas. The references cited within the Wikipedia website seemed credible and peer-reviewed, therefore I deemed it credible.
Although this book has a title that seems like it would be very useful, it turned out to be my least useful source. This is because the book was too difficult for me to understand. This book seemed like it was written by scientists for scientists. It thoroughly covers the solar corona and takes into account the major observational and theoretical developments of recent years in the understanding of the solar corona. Rarely did the text break things down in “lamens terms”, which was the kind of book I was looking for. However, it did assist in helping me deduce where the electrons and particles are located within the corona when I read about the properties of electrons within it. It stated how electrons in motion to the observer possess a magnetic field that deflects off other magnetic fields. This is how I concluded that the electrons and particles are located within the magnetic field of the sun and moon. I deemed this source credible due the complexity and depth of the content. I was also published by Cambridge University Press, which seemed credible as it is an off-shoot of an accredited university that is often labeled as "prestigious". It's first publication was in 1584, and they publish over 2500 titles and 200 journals a year.
This book proved to be very useful due to it's in depth analysis of the anatomy of the human eye. I used the book for assisting in my answer by utilizing information from it in the form of an in-text citation. It assisted in explaining the light-diffracting attributes of the corneal surface and the crystalline lens, which is a crucial part to explaining an entoptic corona. I believe this is a very reliable source. It is a fairly recent publication that was written by a group of highly qualified medical scientists, and I found it within the UW library. Not all books found at the UW library are necessarily credible, but for this topic I believe most of the books are. Also, this was the third edition of the book, which reinforces my notion of it being up to date with modern medical beliefs.