Let’s start with a sample photo from the newly upgraded Hubble Space Telescope:
There are several very bright objects in that image. Why do only some of them have (pardon me if this is the incorrect term) lens flare?
I’m guessing those with lens flair are considerably brighter, but your monitor can’t ‘show’ the brightness higher than pure white. Somewhere in the process the brightnesses have been ‘defaulted’ to pure white.
ETA: That’s not the technical answer. Just my understanding of what’s happening. I could be off the mark,
I think you’re referring to the pattern of four spikes. These are diffraction artifacts caused by the four vanes that hold the secondary mirror. It is in a housing that partly blocks the open end of the telescope, and the vanes keep that housing in place.
Stars are practically points of light, and the diffraction spikes are visible for them because the star’s image is so small and so intense. The larger objects are spread over more area and their spikes are smaller.
At least, that’s what I think you’re noticing, and why.
This type of difraction also occurs in SLR lenses that are stopped down to small apertures for similar reasons; apertures are not perfect circles but multiple blades that close down. Here is an example (hot link but it’s my web site :))
Lens flare occurs when a bright light, particularly at the edge or just off the edge of the frame, causes internal reflections in the lens giving a kind of visual echo effect. Here is an extreme example.
