The Beginner's Guide to Making a Star

NASA/GSFC/U. Hwang et al Chandra X-ray Images of the Cas A supernova remnant

Cassiopeia A is too faint to view with the unaided eye, but it's easy to see where the remnant is in the northern summer sky. Simply go outside just after sunset and look 45 degrees above the north-north east horizon between the constellations Cepheus and Cassiopeia.

Even after more than 10 billion years of star formation, hydrogen and helium still are overwhelmingly the dominant atoms in the cosmos. Heavier atoms like the ones we see in the shell of Cas A are over represented on Earth because H and He are volatile gases that solar heating drives from the low-gravity terrestrial planets. Massive Jupiter, on the other hand, is made up almost entirely of hydrogen, as is the Sun.

Heavy elements may be no more than rare cosmic pollutants, but they are exceedingly important to us. Without them, solid, rocky planets would be impossible, and the prospects for Earth-like life would be correspondingly dim. As it is, the iron we see now in Cas A might one day flow as hemoglobin in the blood of some future alien species. Fast moving knots of silicon from the supernova could provide the raw material for sand on otherworldly shores, where crashing waves of H₂O send thunderous sound waves through a nitrogen-rich atmosphere. And just perhaps, on that fanciful alien world, hardworking science students distracted by the beckoning sounds of distant waves might wish for less organic chemistry and more time on the beach.