How Planets are Formed

Our planets in order from proximity to the sun

How Planets Are Born: A Cosmic Story You'll Adore

Picture the universe as a huge kitchen. Way back when the Big Bang happened, ingredients spilled all over the place —dust, gas, ice, and little pieces of rock— floating around freely like sprinkles in a galaxy-sized cupcake mix.  So, how did all of that untidy space material end up making up pretty planets such as Earth, Mars, or even the ones way, way away from home? Buckle up your space helmet because we are going to bake some planets!

The Party Starts with the Dust

It all begins within a thing called a nebula — a vast, rainbow-colored cloud of dust and gas.(If you've looked at pictures of the Pillars of Creation, that's a nebula!) Gravity throws a party in places within the nebula. Dust and gas begin to gather because gravity pulls everything towards the center. As more material comes together, it gets denser and warmer, similar to when a snowball gets tighter and tighter.

Our Sun was born from one of these celebrations around 4.6 billion years ago!

Baby Planets (Planetesimals) are Born. As gravity continues to act, smaller clumps begin to form. Clumps are referred to as planetesimals —small, nascent versions of worlds. Imagine them as balls of cookie dough before turning into complete cookies. They begin colliding with one another. Occasionally, they shatter (ouch!) when they collide, but at other times they combine and enlarge. Those who survive the melee only get bigger and bigger.

Certain planetesimals ended up as asteroids and comets that are still whizzing through space today! The Final Touch —Clearing the Neighborhood— When a planet-forming body becomes sufficiently large, it becomes a protoplanet. It resembles a teenage planet, nearly mature but still navigating a few clumsy impacts. An actual planet must claim its orbit —it becomes the ruler of its area of space. It swallows up nearby items, pushes them out with its gravity, or holds them as moons.

Riddle Time!

I turn, I dance, I illuminate the sky

But when I'm tiny, I assist planets to fly.

What am I?

(Answer: Dust!)

What Makes Some Planets Enormous and Gassy? 

Near a star, it is too hot for light gases such as hydrogen and helium to remain. Rocky planets such as Earth, Mars, and Venus were, therefore, formed there. Further away from the Sun, it’s cold —a never-ending winter. Out there, gaseous worlds such as Jupiter and Saturn might build up to enormous sizes by absorbing all the light gases and ice particles. (Space vacuum cleaners, essentially!)

Instant Cosmic Recipe for a Planet:

✨ 1 Nebula (gas-rich and full of dust)

✨ Add a dash of gravity

✨ Countless millions of years of clumping, crashing, and flourishing

✨ Optional: Add rings, moons, or storms for added flavor!

Et voilà! You've constructed a planet! 

Each planet that you can see —from Mercury whirling around the Sun to far-away ice worlds we have never even named— began as a speck of dust drifting through the cosmos. It’s as if the universe grabbed a handful of nothingness and shaped everything. Doesn’t that sound magical?

So, the next time you glance up at the evening sky, keep in mind: it all started with a little dust... and a whole lot of cosmic imagination.