Telescopes can have simpler optics, as they only have to focus at infinity. The Hubble Space Telescope has two mirrors. Notice in this picture how the secondary mirror is supported using four struts. This is the reason stars appear to have four spikes in the photos taken by Hubble. (source, example). Diffraction spikes can also occur here on earth :P , caused by the shape of an aperture, dust on the lens, or even the anatomy of our eyes!