This image demonstrates the power of the invisible in astronomy. Whereas visible light images of this supernova remnant show only faint wisps of gas, this radio image reveals a wealth of detail. The first thing one notices is the bright but thin ring centered on the point in the sky where the Danish astronomer Tycho Brahe first observed the supernova explosion in 1572ΓÇöstrong evidence that the nebula is in fact a supernova remnant. The shape of the bright regions shows where the expanding wave of gas ejected from the explosion is colliding with the interstellar gas and dust that sur- rounded the original star. Although the nebulaΓÇÖs bright areas appear as a ring in this two-dimensional image, the true shape is roughly
