interesting photo of a U.F.O. or a very spectacular lens flare! check this out!, page 2

Originally posted by PhoenixOD
The link you provided says "They are artifacts caused by light diffracting around the support vanes of the secondary mirror. " but obviously there is only 1 mirror in a SLR.

Don't forget, with an SLR the mirror is always out of the "light path" when you take a photograph. In an SLR lens, it's the edges of the diaphragm blades that are responsible for diffraction rather than the support vanes.

The point is that diffraction is related to the size of your aperture, weather or not mirrors are used in the optic/lens, and not all night/long-exposure photography will necessarily result in diffraction spikes around bright light sources:

Every photographer wants both maximum resolution and maximum depth of field. But unfortunately these two demands can be mutually exclusive. As you stop down the aperture on a lens the light passing through tends to diffract, reducing sharpness, though DOF is increased. The reason for this is that the edges of the diaphragm blades in the lens tend to disperse the light. At larger apertures this diffracted light is only a small percentage of the total amount of light hitting the sensor or film, but as the aperture is stopped down the amount of diffracted light becomes a larger percentage of the total amount of light being recorded.

Source: luminous-landscape.com

Originally posted by PhoenixOD
Ill try drastically adjusting the f stop next time im out doing night time long exposure and see the results.

It's worth a go. Try a fast lens if you have one