November ’24 Focal Plane – Discovering the Stars

For millennia, humanity has looked up at countless tiny points of light in our night sky – and wondered.  What are the stars, and how did they get there? How far away are they, how big are they, why do they shine? In the last few centuries, astronomers have learned a great deal about the lives of stars – how they form, live, and die. Astronomers estimate that the universe could contain up to one septillion stars – that’s a one followed by 24 zeros. Our Milky Way alone contains more than 100 billion, including our most well-studied star, the Sun.

What remarkable discoveries have been made about the properties of stars? Stars are giant balls of hot gas – mostly hydrogen, with some helium and small amounts of other elements. Every star has its own life cycle, ranging from a few million to trillions of years, and its properties change as it ages. A star’s gas provides its fuel, and its mass determines how rapidly it runs through its supply, with lower-mass stars burning longer, dimmer, and cooler than very massive stars. More massive stars must burn fuel at a higher rate to generate the energy that keeps them from collapsing under their own weight. Some low-mass stars will shine for trillions of years – longer than the universe has currently existed – while some massive stars will live for only a few million years.

Our presenter for the November General Meeting was Professor Joe DalSanto. He is a lifelong amateur astronomer who has spent countless nights observing with telescopes up to 30” aperture from numerous locations throughout the US. He is Chair of the STEM Department and Professor of Astronomy at the College of DuPage and is the author of three published textbooks for their astronomy courses on astronomy including “Observational Astronomy for Undergraduates”. He never tires of simply viewing the sky and marveling at how much we have learned about our universe.