Welcome to the Astro Minute, where we’re exploring the universe sixty seconds at a time. I’m Lauren Smyth, and today we’re looking at middle-aged stars.



After hydrogen fusion begins in the core of a protostar and a new star is born, it enters a long stable stage of life where its outward-pushing gas and radiation pressure balances its inward-pulling gravity. This stage is called the main sequence. 



Without optical aid, only a few medium-mass main sequence stars, including our sun, can be seen. Most naked eye main sequence stars are high-mass stars: they burn the brightest, and the fastest, having shorter lifespans and more violent endings than smaller stars.



Look for these bright high-mass main sequence stars: Rigel in Orion, Vega and Altair in the Summer Triangle, and the bright stars in the Pleiades.



I’m Lauren Smyth, and that’s your AstroMinute.