Starship Asterisk*

those M44ians must be very happy to have this comet gracing their skies...........wait a minute .!!!

Nitpicker wrote:I realise that any unresolvable point source of light can only ever be observed as a diffraction pattern. But are some patterns better (or more natural) than others?

The shape of the diffraction pattern is determined by the shape of the aperture. While there times when apodizing masks or specially shaped apertures are desirable (for example, to separate close double star pairs), for most scientific applications an unobstructed circular aperture is generally the ideal. For aesthetic images, it's a matter of choice. Personally, I prefer images without diffraction spikes. But other people like them- enough that they will add them, either optically (by stretching string across the aperture) or by some image processing trick.

I've been looking for Comet ISON with binoculars on clear mornings -- no luck so far. But this morning I saw Comet Lovejoy (C/2013 R1) and it's beautiful! High overhead before dawn (about 0430 PST) in eastern Cancer heading toward northwestern Leo. A large nebulous object, easily visible in 11x56 binoculars. I'm sure it's visible in smaller binoculars, too.

This Sky and Telescope article, linked to in the apod caption, provides detailed finder charts for Lovejoy and ISON for the next few days. Go outside and look for yourself. You could stretch a couple of lengths of string across the front of each binocular objective if you really like diffraction spikes.