Question of the week: I heard from some Christians that the theory of star formation from gas clouds is unproven and that astronomers have never seen a star form from an interstellar gas cloud. Since the gas in gas clouds wants to disperse, especially when a gas cloud heats up, how can gas clouds ever condense to form stars and planets? Are these Christians right in stating that stars must have been created by God’s fiat miracles?
My answer: God is responsible for the existence of stars just like he is responsible for everything in the universe. However, not every component of the universe arises by a divine fiat miracle. As raindrops form from the ongoing physical processes operating in tropospheric clouds, so, too, do stars form from the ongoing physical processes operating in interstellar clouds. The reason some Christians deny that stars form in such a manner is that the formation process typically takes many millions of years and their personal interpretation of the Bible’s first chapter only allows for 6,000–10,000 years.
Astronomers who are not beholden to a young-universe interpretation of Genesis 1 consider the theory and observations of star formation from interstellar gas clouds to be settled. It is settled but not necessarily simple. For a star to form from an interstellar gas cloud, the gravity that forces part of the gas in the cloud to collapse must be stronger than the radiation forcing that gas to expand. Where it gets complicated is that some outside gravitational fields can cause or disrupt cloud collapse and some outside radiation fields can accelerate or disrupt cloud expansion. Astronomers observe both collapsing and expanding small gas clouds within larger interstellar gas clouds.
It is true that no astronomer has observed the entire process of star formation. That process is much longer than the lifespan of any astronomer. However, by making observations of thousands of different collapsing gas clouds, astronomers have witnessed all the stages of star formation. There are several astronomical websites where laypeople can see hundreds of images of these different stages. Astronomers have now studied and understood star formation to sufficient depth to recognize that the physics of star formation actually is simpler than the physics of raindrop formation. There are several undergraduate-level textbooks on star formation that are accessible for laypeople. Two I like are Principles of Star Formation by Peter Bodenheimer, and An Introduction to Star Formation by Derek Ward-Thompson.