True stories have many beginnings.
Perhaps the story of Honeysuckle Creek and of man’s journey to the Moon began more than 40,000 years ago, when the people of the Ngunnawal and other Indigenous nations who lived and visited near what would one day be called Honeysuckle Creek gazed up each night between the hills at the Emu in the Sky.
When we look up at the night sky we see lines of stars dotted across the blackness. The stars form shapes — Orion’s Belt, the Big Dipper and the Southern Cross. But the shape of the Emu in the Sky is formed from the dark spaces of the Milky Way, not from the stars. Its head is near the Southern Cross, its body stretches across Scorpio and, in winter, its legs reach to the horizon.
You can only see the Emu if you are far away from man-made light — in towns there are too many bright lights to see most of the stars, so the dark shapes between them are lost as well.
When the Indigenous space watchers saw the Emu in the Sky with its legs folded up under its body (or in our terms, the densest part of the Milky Way was rising), they knew that they would have lots of eggs to eat because male emus on Earth would then be sitting on their eggs.
Even today you can see Aboriginal rock-art emus near Honeysuckle Creek in the shape of the Emu in the Sky.
And still every month the full Moon rises, round and golden, above the tiny creek among the trees — where there was once a space tracking station that followed the journey of the men who travelled to the Moon.
The asteroid collision that helped wipe out the dinosaurs was only a hiccup compared to the collision that made the Moon 4.5 billion years ago! Earth was still molten then. In fact it wasn’t really Earth as we know it today, but a ‘proto-Earth’ — a planet only half the mass it is now. However it was rapidly getting bigger as it gobbled up rubble that had condensed from the dust cloud swirling around the young Sun.
A rival planet was also orbiting the Sun dangerously close to our ‘proto-Earth’. This giant blob was about one-third the size of Earth. Both were hot, turbulent places with molten rock mantles wrapped around ferocious dense cores of liquid iron.
One day the two planets collided, spewing enough dust, rock and vapour into orbit to form a broad ring about 12,000 kilometres above Earth. The Moon was formed from the outer edge of the ring of dust and rock while the inner part of the ring fell back to Earth. The new ‘Moon’ then slowly swung further out into orbit about 380,000 kilometres from Earth — which is where it is now.
How do we know? Why couldn’t the Moon have been formed from giant swirls of matter spat out by a madly turning early Earth?
The answer is iron. When the two giant bodies collided their heavy molten iron cores melted together, while part of the rocky outer parts splashed out to make the Moon. So now 30 per cent of Earth is iron, but iron only makes up 2 per cent of the Moon. If the Moon had been made from the same material as the whole Earth, it would have a similar percentage of iron and other matter.
It all probably happened very fast — a few hours for the two planets to collide, a few weeks for the present Earth to form from what had been two mini planets, with a ‘young Moon’ orbiting about 20,000 kilometres away.
That ‘ancient Earth’ was still much smaller than our Earth is now. It took about 50 million years of more asteroid and meteor collisions to make Earth and the Moon the actual sizes they are now. The close presence of the Moon and its gravity gradually slowed down the madly spinning Earth giving us the comfortable 24-hour day we now have.
Most other planets have moons that are tiny compared to ours — our Moon is about one-quarter the size of Earth. Having a big moon close by stops Earth from wobbling around too much on its axis — giving us regular seasons with no wild climate swings.