From Stars to Stones: How Astronomy and Geology Tell Earth’s Cosmic Story

September 23, 2025

Metals, Planets, and the Cosmic Story Beneath Our Feet

“We are made of star stuff.” – Carl Sagan

Hello, fellow sky-watchers!

I just came back from a study trip to Hanle in Ladakh—a place many call the roof of the Earth. I went there as an amateur astronomer to enjoy the stars, but something else caught my eye. It was not only the night sky, but also the rocks and land beneath my feet.

Under those clear skies, the Milky Way shone so bright that Orion almost looked crowded. It was nothing like the skies back home in Pune, where city lights dim the stars. For a moment, I imagined how ancient people might have read by starlight. But then, the geology of Ladakh pulled me back down to Earth.

I asked myself: could the land beneath me and the sky above me be telling the same story? The answer, I realized, was yes. Both astronomy and geology are threads of one big cosmic tale.

The Cosmic Pancake: How Planets Begin

Around 4.6 billion years ago, our Solar System was not planets and moons. It was just a spinning cloud of gas and dust. Scientists call it a protoplanetary disk.

Think of it like pizza dough spinning flat. At the center, gravity pulled matter together until the Sun was born. Close to the Sun, only tough stuff like iron, nickel, and rock could survive the heat. Farther away, things like ice, water, methane, and ammonia stayed solid.

That is why the planets are so different:

Near the Sun: Rocky planets (Mercury, Venus, Earth, Mars) with iron and rock.
Farther out: Gas giants (Jupiter, Saturn) full of hydrogen and helium.
Even farther: Ice giants (Uranus, Neptune) with frozen water, methane, and ammonia.

This pattern still guides us when we look at other star systems today.

Earth: A Planet Sorted by Fire

After Earth formed, it was a hot ball of melted rock. Giant space rocks smashed into it, and radioactive elements heated it up. The Earth melted like a furnace, and the elements separated by weight.

Heavy metals like iron and nickel sank into the core.
Lighter rocks like silicon and magnesium floated in the mantle.
Sulfur-loving elements like copper, zinc, and lead got stuck in between, often with sulfur.

That is why we do not see much iron in the crust today—it is mostly locked deep inside Earth’s core.

Geology as an Artist

Over time, plate tectonics and volcanoes began painting Earth’s surface. These forces moved continents, raised mountains, and even placed metals where we could reach them.

Gold gathered in shiny veins.
Copper spread in volcanic zones.
Iron ores rose near the surface.

So, the big picture was set by space, but the details were painted by geology.

A Telescope’s View of the Story

As an amateur astronomer, I see this pattern in the night sky too. When I point my telescope at Mars, I see a rusty red desert. That color comes from iron oxide, the same element we have on Earth.

When I look at Jupiter and Saturn, I see swirling clouds of hydrogen and helium, with touches of methane and ammonia. The way elements are spread across the planets matches what scientists expect from the early Solar System.

The Cosmic Rulebook

The pattern is simple:

Close to the Sun → Rocky planets with metals and silicates.
Farther out → Gas and ice giants with lighter elements.
On Earth → A heavy iron core, a rocky mantle, and special metal deposits shaped by tectonics.

It’s like the universe follows a recipe, and every planet is a dish baked in the same kitchen.

Back in Ladakh: Sky Meets Stone

Standing in Hanle, I felt a strange connection. The stars above told me how the Solar System formed. The rocks below whispered about tectonic collisions that made the Himalayas.

Both stories are one. The mountains around me rose because of plate tectonics. And plate tectonics happened only because Earth had a hot, active inside—a story that began in the protoplanetary disk.

Holding a piece of iron ore or a gold rock is like touching the memory of planet birth. It is a gift from space, carried through time.

Why This Matters

You may ask, “Why should we care?”

Because this story reminds us that:

We are part of the cosmos.
The rocks we mine and the stars we see are chapters of the same tale.
Astronomy and geology are not separate—they are two voices in one song.

Final Thoughts

Hanle gave me more than a starry sky. It gave me a bridge between Earth and sky. The Himalayas and the Milky Way spoke the same truth: the universe leaves its fingerprints everywhere.

As an amateur astronomer, I find comfort in this. Each night when I look up, I see not just stars, but also the story of the ground I walk on.

About the Author

This blog was composed by Bhanu Srivastava an amateur astronomer based in Pune India. Bhanu has a deep interest in exploring quantum biology and the many open questions in astronomy. He is passionate about learning and sharing knowledge about the universe with others.

Bhanu also runs a LinkedIn group dedicated to discussions on astronomy. If you're interested you can join the group here:

https://www.linkedin.com/groups/9800085/SS