[gaseous (Patrick)]

Last night I gave my Skywatcher 20" dob its maiden voyage, and one thing I noticed was the extreme "diffraction" for want of a better word, on very bright stars.



On normal stars, or at lower magnification, I generally saw just the normal 4 spikes you'd expect, but the attached photo is of Alpha Centauri. While the photo doesn't really do it justice (It was sharp and easily split but my smartphone photographic skills are virtually non-existent), you can clearly see the wild rays coming off it.



Would I be right in thinking this is some function of the ribbed primary mirror design, and is it normal? I was only out for about 3 hours, so maybe the mirror hadn't completely cooled, despite the chilly conditions and moderate breeze, but it hadn't shown any sign of improvement by the end of the night. Any comments/suggestions would be most welcome.