Earth may have underground 'ocean' three times that on surface

[Anomalocaris]

The amount of dumb that you kept from the idiocy comet that hit you leaves you with no room for diamonds and gold.

The accretion of the earth from protoplanetary disk was mostly completed in less than 100 million years, most likely within 1-10 million years, 4.6 billion years ago. 99.9% of impacts earth will likely ever experience happened in those 1-10 million years. Most of the remaining 0.1% impacts that earth was yet to experience at the end of its formation likely occurred in subsequently in a single brief episode, called late heavy bombardment, around 3.9 billion years ago.

The fact that rate of impact by comets and asteroids were many orders of magnitude higher at the beginning of solar system's history than now is well attested by the ages of craters on the moon, mars, and mercury. It is also indirectly attested by geological record of the earth.

Current rate of cometary impact on earth is estimated at one dino killer sized comet every roughly 100 million years, 1 Haley sized comet (15 miles) every roughly 2 billion years. During earth's first few million years the impact rate would have been roughly 1 Haley sized comet every few years. During late heavy bombardment it would have been 1 Haley sized compet every few thousand to tens of thousands of years.

A Haley sized impact would end human civilization and cause a mass extinction event that would dwarf the one which killed the dinosaurs and ended the Cretaceous, and probably kill most if not all mammals, including humans.

[Wyrd of Gawd]

It's going to rain soon so I'm going to see if I can spot the comet that brings the rain. They're sneaky and hard to catch in the act but sometimes they make a lot of noise and light up the sky with long streaks of light that hit the ground as they pass through the sky.

If it was true in the past it should still be true today, right?

[The Grand Nudger]

Even the average nuts who advocate the magic comet theory say that it could have taken up to a couple of billion years for the comets to have brought all of that water to Earth. Now it's down to as little as 1 million years? It's a good thing that they don't hit us today with that frequency. If a gold or diamond comet slams into my backyard can I keep it?

-that would depend on how many of the total pool of comets we've already hit/been hit by. If there are only so many things in your way - and you just keep going round the same way again and again - eventually everything will either be stuck to your grill or laying on the side of the road. I imagine the first lap would be hell - and the last lap heaven, from the point of view of not wanting to get hit by a comet.

[Cyberman]

If it was true in the past it should still be true today, right?

Depends on the context. There were far more cometary (and other large protoplanetary debris) impacts in the past, because the planets were still being formed and there was considerably more debris to collide. The Solar System now enjoys relative stability, since any object not in a stable orbit has either impacted and/or merged with an existing planet, plummented into the Sun, or been flung out of the system altogether; though objects do still encroach on planeteray orbits and do, on occasion, collide. It's the difference between traffic at rush hour and the same street at night, or a Snooker table at the start of the game compared with the same table towards the end.

[Anomalocaris]

It's going to rain soon so I'm going to see if I can spot the comet that brings the rain. They're sneaky and hard to catch in the act but sometimes they make a lot of noise and light up the sky with long streaks of light that hit the ground as they pass through the sky.

If it was true in the past it should still be true today, right?

You didn't exist in the past. Therefore you still don't exist today, right?

[LostLocke]

It's going to rain soon so I'm going to see if I can spot the comet that brings the rain. They're sneaky and hard to catch in the act but sometimes they make a lot of noise and light up the sky with long streaks of light that hit the ground as they pass through the sky.

If it was true in the past it should still be true today, right?

Kudos on your outstanding example of a strawman!

[Wyrd of Gawd]

Comets brought the rain in the past. It still rains today. Therefore comets are still bringing the rain otherwise it wouldn't rain.

The Earth, which is a dynamic living planet, is incapable of making its own water and it depends on the comets for it. 's too bad those water comets always seem to miss the desert areas. Maybe someone should paint some bull's eyes in the deserts so that the comets will rain on them more often.

Let's start a competition and see which one of us will be the first to catch a sneaky comet bringing a fresh load of that nice fresh water we get from the sky. Be sure to keep watch because I will. Heck, we might even see Jesus and his angels coming down from the clouds. He's supposed to be here at any time, according to the book.

[Tonus]

I don't understand how we got from "comet impacts brought water to the planet" to "comets make it rain."

[Jackalope]

Comets brought the rain in the past. It still rains today. Therefore comets are still bringing the rain otherwise it wouldn't rain.

Promise us you'll never reproduce.

[Cyberman]

Are we still missing the part where it doesn't have to be all or nothing? That huge gaping crevasse inbetween, where both options apply?