[CliffordK]

Good point that numbers are just numbers, and really only have significance to humans.

And, we can't even agree on the significance of certain dates, for example the Russians and the Romans can't agree on which day Christmas should be observed.

The orbital period of Earth around the sun, of course, has significance to us when coupled with Earth's axial tilt.  However, even that would hardly have a lot of significance to long period comets, except for whether or not Earth gets in their way.

[CliffordK]

Whew, just 2 weeks left until the end of the world.

[bizerl]

Whew, just 2 weeks left until the end of the world.

2 weeks? 13/12/12? That would be the ultimate joke! Imagine the headlines. "World ends one week early! Doomsayers get it wrong!"

Oh, wait...

[Don_1]

You mean to tell me the world is going to end before the 25th.

WOW!!! In that case, I'm not buying anyone any presents.

Do you think I can get a refund on the 2013 calander I bought the other day? I wondered why it was blank!

[RD]

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[CliffordK]

Ok, so I had confused 12/12/12 with 12/21/12

I keep looking out my window for a comet heading towards Earth, and all I see are clouds.

Would a comet heading towards Earth have a visible tail?

[RD]

Would a comet heading towards Earth have a visible tail?

A comet would develop a tail when within the orbit of Jupiter (approx 6AU from the sun).
An asteroid wouldn't have a tail ...

One of the most recent close calls occurred on March 23, 1989, when an asteroid 0.25-mile (0.4-kilometer) wide came within 400,000 miles (640,000 kilometers) of Earth. Surprised scientists estimated that Earth and the asteroid -- weighing 50 million tons and traveling at 46,000 miles/hour (74,000 kilometers/hour) -- had passed the same point in space just six hours apart.

http://nssdc.gsfc.nasa.gov/planetary/text/asteroids.txt

[Sagitarious]

Nothing will be happened that day u all know that every day lots of peoples are died and born so this is not the logic that, in this day world is finished so relax GOD knows better that day because he make this world and he finish it. But not now. So relax...do your work..

[CliffordK]

Yes....
But, if the comet is heading towards Earth.
Then our view should be head on...  the tail would generally be behind it...

So, it should appear as a single spot, perhaps blurry around the edges.

Of course, if it was visible for a month or so, then Earth would be slowly orbiting around the sun, and may initially have a partial side view.

[Raziel]

it was the aztecs not the mayans that predicted a cataclysmic end to the world age ending on the solstice. they said the world would be destroyed by earthquakes. lot's of fracking triggering earthquakes lately. Now the tibetan oracle of Sham-bala says that indeed we will have a mini apocalypse which is linked to earthquakes. he says the world won't end but we will lose 10% of the world population and people in cities will lose their minds. he says don't look out your windows cuz ghosts will appear to be everywhere and that we will have no electric power for two months.

[CliffordK]

it was the aztecs not the mayans that predicted a cataclysmic end to the world age ending on the solstice. they said the world would be destroyed by earthquakes. lot's of fracking triggering earthquakes lately. Now the tibetan oracle of Sham-bala says that indeed we will have a mini apocalypse which is linked to earthquakes. he says the world won't end but we will lose 10% of the world population and people in cities will lose their minds. he says don't look out your windows cuz ghosts will appear to be everywhere and that we will have no electric power for two months.

The doomsday predictions can be quite extraordinary. 
Although, if you look at the storms in NY and New Orleans, as well as past earthquakes in Japan and California, it is clear that our infrastructure is quite vulnerable to insults, and it can take weeks or months to even make a partial recovery in a hard-hit area. 

It would take a huge cataclysm to wipe out 10% of the global population. 

• Disease
• War
• Yellowstone Eruption
• Global lost growing season, likely due to atmospheric particles
• very large body strike

Perhaps a combination of the above.

Even a synchronized earthquake along a fault line, say from San Diego, LA, San Francisco, and extending up into Oregon, and Washington, Canada, and Alaska.  It would still likely leave the overall global population loss far less than 1%. 

[bizerl]

Does anyone know what time the apocalypse is scheduled? I've got some christmas shopping to do and would hate to miss the shops before they explode in a fiery inferno.

[Don_1]

Well, I'm still here.......

No ghosts, no power cuts, no rending of the Earth's crust, no comet........

BUT WAIT, That's it..........

Yes, those Mayans were right all along...... just a couple of days out...... http://www.bbc.co.uk/news/business-20765983

[CliffordK]

Well..  a few hours left of the 21^st.  And, so far no comet.  But, of course, with all these clouds, I'd never see it coming.

Perhaps the Mayans were predicting the coming of the fiscal cliff

Consider a long period comet such as Haley's comet.  Perhaps with close astronomical calculations, they could have discovered its period as Haley did.  But, even so, Earth is a very small target, astronomically speaking, to be shooting at. 

Even with far better telescopes than the Mayans had, it is hard to predict Haley's position 75 years into the future to within about 10 minutes, and 12,000 km which would be necessary to predict a collision course with Earth.

What about a longer period comet?  300 years?  500 years?

[Bored chemist]

Well, it looks like the world hasn't come to an end so I'd better go and celebrate Christmas/ the Solstice/ Saturnalia/ any excuse to stop work for a while.

Hope you all have a fun time in the coming orbital period of your choice.

[Don_1]

Damn! And still I'm still here!

I bought a Lamborghini yesterday and thrashed it into the ground thinking 'what the hell, I'll never have to pay for it'. Boy am I gonna be in the s**t when the credt card bill comes in.

Bloody damn fool Mayans.