You Can't See The Brightest Star In The Sky

NASA's Fermi Gamma-ray Space Telescope has discovered a faint but sprawling glow of high-energy light around a nearby pulsar. If visible to the human eye, this gamma-ray 'halo' would appear about 40 times bigger in the sky than a full Moon.

From here. 

"Biggest" would be more accurate than "Brightest", but I claim poetic license for the post title. Gamma rays are in the deep ultraviolet beyond the wavelengths of visible life, which is why you can't see it.