A blazing ball of fire lies deep underground. It’s Earth’s core. This colossal sphere of molten iron far beneath your feet is what made your life on Earth possible. Or did it? What if Earth formed without the scorching core in its center? Is a coreless planet even possible? How different would Earth be without its core? If it didn’t exist, would you still be alive?
Underneath 2,900 km (1,802 mi) of crust and mantle lies the core of our planet. This mighty ball of molten iron has a radius of about 3,500 km (2,175 mi) and temperatures of 10,000 °C (18,032 °F). That’s even hotter than the surface of the Sun. It was formed during the iron catastrophe, a major geological event early in the history of our planet when Earth was heated to temperatures above the melting point of iron.
Droplets of heavy metals gravitated toward the center of the planet while lighter elements rose to the surface and formed its mantle and crust. The core’s scorching temperatures are the result of energy left over from the formation of the Earth and nuclear energy from natural radioactive decay. And it is the motion of the molten metal of the outer core that is responsible for Earth’s magnetic field. You know, the thing that protects us from harmful cosmic radiation. No biggie.
So how nasty would things turn here if Earth formed minus its core? In order to form, planets require iron, lots of it, to fall toward their center. Eventually, this iron becomes their core. Scientists think planets with no core could also exist, which happens when iron becomes oxidized and trapped in a planet’s silicate mineral crystals or mantle.
In these cases, the iron doesn’t form a core and the planet goes on with its day-to-day existence without a scalding sphere at its center. So what would happen if our very own Earth formed like that? In order to be habitable, a planet requires warmth and water. It needs to be sheltered from a young, violent star like our Sun.
A magnetic field acts as a planet’s shelter and is created when its core cools and solidifies, disturbing the liquid iron around it and sending out electric currents as a result. So if the Earth formed without its ball of molten iron, it wouldn’t have a magnetic field. This would expose us to harmful cosmic radiation and charged particles emitted by our Sun.
We’d also be blasted by ferocious solar winds. Without its magnetic field, Earth could lose its atmosphere. Just look at our nearest neighbor, Mars, for the repercussions of that. Long ago Mars DID have a strong magnetic field, but it wasn’t meant to last.The Martian core froze around 4.2 billion years ago and that dramatically weakened its magnetic field.
So weak it couldn’t keep its atmosphere protected. Solar winds mercilessly chipped away at it, slamming into the planet at speeds reaching approximately 800 km/s (500 mps). So you could guess what would happen to Earth if it didn’t have a strong magnetic field like it does now. Instead of being a place warm enough to store salty oceans where life could thrive, our world would end up as a cold, dry and lifeless desert.
If life on this coreless Earth emerged, it would need to adapt to some extreme changes. An intense barrage of UV rays would be a constant threat, as they could damage your DNA. Most likely you would have to live underground, where you’d be less exposed to cosmic radiation. If you stayed on the surface of a coreless Earth, you’d always see flashes of light, even with your eyes closed.
This would be the result of cosmic rays passing through your retinas. Some animals, like birds and whales, wouldn’t have the magnetic field to use for their navigation. All life on Earth would have to adapt to living in much harsher environments. But wait. There’s more. You wouldn’t have all the great technology that relies on our magnetic field.
That’s right. Satellites, telecommunications and navigation systems…. None of them would exist. I don’t know about you, but I’d rather be born on Mars than on a planet with no core. And you should probably know that our planet’s core is slowly losing heat. Eventually, our hot ball of molten iron will become solid.
Scientists predict it would take 91 billion years for the core to go completely solid. Luckily or not, the Sun would run out of fuel, expand into the red giant and swallow the Earth long before its core gets completely cold.
- “Planets Without Metal Cores May Be Bad For Life”. Ker Than. 2008. newscientist.com.
- “Earth-Like Exoplanets May Have Magnetic Fields Capable Of Protecting Life”. 2015. exoplanets.nasa.gov.
- “How Mars lost its atmosphere, and why Earth didn’t”. Joel Achenbach. 2017. washingtonpost.com.
- “Astronomers Show Magnetic Field Is Critical For Life”. Harvard-Smithsonian Center for Astrophysics. 2016. scitechdaily.com.
- “Are Solar Storms Dangerous To Us? | Space”. Deborah Byrd. 2020. earthsky.org.