Hadean Eon
Earth 4.5 Billion Years Ago: A Magma Ocean and a New Moon
What Earth was like 4.5 billion years ago: a molten world just struck by the Mars-sized Theia, with a newly formed Moon only a few Earth-widths away.
Spin it in 3D and move through timeNo map of the land exists this far back: the globe is an illustration of what Earth was like.
Map: Ancient maps: PALEOMAP PaleoDEMs (Scotese & Wright 2018), CC BY 4.0.
Earth was only tens of millions of years old 4.5 billion years ago, and it had just been hit by a protoplanet about the size of Mars, called Theia. The collision melted much of the planet into a magma ocean hundreds of kilometres deep and threw a disc of molten and vaporised rock into orbit.
That debris gathered into the Moon, which at first orbited far closer than today, perhaps only 20,000 to 30,000 km away, and loomed huge in the sky. Earth spun fast, with a day of about 5 to 6 hours, and the young Sun shone only about 70% as brightly as it does now.
There were no continents, no oceans of water and no life. The air was a thick mix of rock vapour, steam and carbon dioxide. No map of the surface can exist for this time; the globe here is an illustration.
Events of the time
Theia hits Earth
4.51 billion years ago · The whole planet (position illustrative)
A Mars-sized protoplanet struck the young Earth. The debris thrown into orbit gathered into the Moon, and Earth’s surface melted into a magma ocean.
▶ Watch it happen on the globeThe oldest crystals
4.4 billion years ago · Jack Hills, Western Australia (position illustrative)
Zircon crystals 4.4 billion years old carry chemical traces of liquid water, so oceans formed soon after Earth did.
Part of the Formation of Earth & Hadean Eon.