Good question. Actually, early 19th century this question was put forward as an argument against diffraction theory.

The below is from http://minerva.union.edu/jonesc/scientific_photos%202010.htm :

"In 1818, Fresnel presented his theory explaining diffraction of light. Poisson denied the truth of the theory, and argued that a consequence of the theory would be that there would be a bright spot right in the middle of the shadow of a circular object. The spot, shown above of the shadow of a ball bearing suspended on a needle, was promptly discovered by Arago. This was a lot harder to do before lasers were invented!"

Note: observation of such diffraction patterns are best done in (nearly) monochromatic light. Hence the remark about using lasers.

Good question. Actually, early 19th century this question was put forward as an argument against diffraction theory.

The below is from http://minerva.union.edu/jonesc/scientific_photos%202010.htm :

"In 1818, Fresnel presented his theory explaining diffraction of light. Poisson denied the truth of the theory, and argued that a consequence of the theory would be that there would be a bright spot right in the middle of the shadow of a circular object. The spot, shown above of the shadow of a ball bearing suspended on a needle, was promptly discovered by Arago. This was a lot harder to do before lasers were invented!"

Note: observation of such diffraction patterns are best done in (nearly) monochromatic light. Hence the remark about using lasers. The bright spot at the center of a circular shadow is known as an Arago spot.