Oort Cloud, Be Proud!

by Richard Peacock

I was recently contacted by a Christian high-school student who was taught that comets were proof that the Universe is only about 6,000 years old. "How the hell does that make sense?" you may be asking yourself. Well, the young man explained, since comets have a short lifespan** (some for only a few thousand years), then wouldn't they have all vanished by now, if the universe is billions of years old? I wrote back about the Oort cloud, which is a vast field of chunks of material way out past Pluto, which periodically creates new comets. "How the hell does it do that?" you may be asking yourself again. I will now explain, through the art of poetry...

"Oort Cloud, Be Proud!"

Oort cloud, be proud
Of your cosmic contributions!
Hurling comets at our sun,
There to meet forlorn conclusions.

Comprised of chunks of rock and ice,
A swarm of messy debris
At least 2,000 AU's away,
Too far for us to see.

As our solar system moves through space,
You are perturbed by other stars'
Gravitational pulls and tugs,
Though they are very far.



And these little gravitational bumps
Dislodge the chunks from their positions,
And start them creeping towards the sun
On ten-thousand year long missions.

Though your total mass is somewhat small,
(Only five times the mass of Earth)
Your age is probably the same as ours:
5 billion years since your cosmic birth.

It's likely you're the one to blame
For our past global extinctions,
Brought on by comets from the sky
From your outer-solar secretions.



But without extinctions we would not have
Such diversity of life,
Caused by dying species leaving
Open niches full and rife.

New species then evolve
To fill the open niche,
Finding new requirements
That they then must adapt to meet.

So be proud, Oort cloud,
Of your determination and resolve,
For without your planet-killing-comets,
We might never have evolved.

** I wanted to add one more detail about the young man's question: he had been taught that all comets only survive for a few thousand years. This is incorrect. Only "short-term comets" melt away that quickly. Quick fun fact: The Hale-Bopp comet, whose sighting in 1997 prompted the Heaven's Gate cult members to all castrate and then kill themselves, was generated by the Oort cloud.

The Multiverse is written by Richard Peacock, who generally doesn't know what he's talking about, and will gladly sacrifice scientific accuracy for the sake of a rhyme. Send rhyming complaints to richard@amateurscientist.org