Born in Cosmic Clouds: The Start of Every Star
Nebulae are the universe’s workshops. Inside these colorful clouds, gravity gathers hydrogen, helium, and dust—the raw ingredients for new stars.
Nebulae: Where Stars Begin
Inside a nebula, gas twists and weaves. Gravity tugs particles together, forming thicker knots. Most knots stay quiet, but a dense one can plant the seed of a future star.
Gravity Gets to Work
A forming clump acts like a snowball rolling downhill. As gravity pulls in more material, the clump heats and compresses, becoming a protostar—a star in training.
Inside the protostar, pressure rises quickly. The core nears the point where a dramatic transformation is about to start, yet it still needs the final spark.
Why Some Clumps Don’t Make It
Some clumps stall, cool, and never ignite. These brown-dwarfs are too small to shine like stars but larger than typical planets.
Lighting the Fire: Fusion Ignites
When a protostar’s core tops 10 million °C, hydrogen atoms fuse into helium. This fusion releases light and heat—the reason stars glow.
Once fusion starts, outward energy balances inward gravity. The young star settles into a long, stable phase.
Reading the Stars: The Hertzsprung–Russell Diagram
Astronomers sort stars by brightness and color on the H–R diagram. Most stars, including the Sun, live on the main-sequence for billions of years before moving off as they age.
Decades ago, Annie Jump Cannon linked stellar temperature to light patterns, arranging stars into the O-to-M sequence.
What Stars Are Made Of (And Why It Matters)
Cecilia Payne-Gaposchkin showed that stars are mainly hydrogen and helium, not heavy metals. This insight explains their long lifespans and their role in forging heavier elements.
Every bright point above us began in a cold, dark cloud. Through gravity’s pull and fusion’s spark, these survivors of cosmic chaos illuminate the story of our universe.
