DU Astronomers: I need help with the Oort Cloud

[Ediacara]

As some of you may have seen, a club on campus has invited a creationist speaker to do a two night lecture. Tonight was the first lecture, and well... let's just say he didn't do well.

Anyway, during the question and answer period he was asked what he thought the most convincing evidence of a young universe was. He said that comets were.

According to his explanation, astronomers had studied comets, and had estimated that they would all evaporate within 10,000 years (doesn't give a citation), so that means they couldn't have been that old.

I know, it doesn't exactly follow a logical progression.

Anyway, he said that "this astronomer, Dr Oort, that's o-o-r-t" had an idea that there was this area of comets at the edge of the universe and they periodically fall into the sun.

So I raised my hand and was eventually called on, and I asked him two things:

1) Did Dr Oort actually say edge of the universe, or did he say edge of the solar system?

2) What does he think of Oort Cloud objects?

He says that Oort said Universe, and that it doesn't matter anyway, since they'd have to go through the solar system to get here.

I reminded him that there was a tremendous area of real estate between the edge of the solar system and the edge of the universe, and again, he didn't seem to care. I even said that what he was saying was akin to me saying that the difference in distance between Seattle and Portland and Seattle and Pluto was inconsequential.

He just answered that comets would have had to travel through the solar system so it doesn't matter.

He says he's never even HEARD of the Oort Cloud, and that it doesn't exist.

My questions for the DU astronmers are:

1) Has the Oort Cloud actually been documented and photographed? I know there are plenty of Kuiper objects, but I am uncertain of the Oort Cloud.

2) Did never-before-seen comets, like Hale-Bopp and Hyakutake come directly from the Oort Cloud? Even if the answer is no, I think it would be interesting to hear an explanation of where they came from in his opinion.

3) How big is the universe? I ask this because I may ask him tomorrow where Hale Bopp and Hyakutake came from (well if indeed they are directly from the Oort Cloud), and if he still insists the Oort Cloud (if it exists) is at the end of the universe, well then..... I want a speed estimate (and yes I know, it would be something like Warp 146). I actually think I will put it onto a warp speed scale :-)

[SmileyBoy]

1. I can probably help you out:

1) Yes, the Oort Cloud is real. It's a ball-shaped cloud of particles ranging from dust to 10 miles wide in size surrounding the solar system. It's almost certain it exists.

2) I'm pretty sure all comets that have been discovered by humans originated from the Oort Cloud. These objects fall into orbit by being bumped into other objects in that cloud, and falling into the orbit of the solar system.

3) We don't know how big the universe is. Stephen Hawking said that there could very well be parallel universes, but they could never be tapped. Other scientists have had different theories. Our universe as it is stretches out over 10 billion light years away, or close to the very instance the Big Bang occurred. Like I said, The Oort Cloud is at the edge of our solar system, which is an insignificant speck in our universe.

[Ediacara]

5. Thanks

That's exactly what I wanted to know. The guy asked me to tell him all about the Oort Cloud because he's never heard of it. I want to sed him EVERYTHING I can.

1) I know that the Oort Cloud is real, I just wanted to know if it has actually been seen with telescopes. I would like to send him satelite images if I can get ahold of them, but for tomorrow, I just wanted to double check I was remembering correctly.

2) Cool, that's what I thought. I am really curious where he thinks Hale Bopp and Hyakutake came from.

3) I was just wanted a quick and dirty linear dimension of the Universe, which I know is a very tough question to answer. But I wanted it so I can perform a 10B ly in 10Ka means the comets are traveling yadda yadda fast... I actually can't even think how fast that would be, LOL.

[Renew Deal]

2. You might want to copy this into the environment forum.

There are some smart people in there.

[Van Helsing]

3. I can also help

1) Yes, the Oort Cloud has been documented, although I don't know if any pictures exist of it.

2) Yes, they did. Here's a source that can help explain it better than I could: http://www.solarviews.com/eng/oort.htm

3) The universe is 17 billion light-years large. The Oort cloud is only outside our solar system. I don't know what that guy is thinking...

[Ediacara]

6. cool!

Ya, that guy is a freak. Like I have said in some other posts, I realize the Oort Cloud is just surroundig our solar system, but I want a size of the universe, to get a speed estimate for these comets since he insists that no Oort Cloud has ever been found at the edge of our solar system.

[undergroundpanther]

4. Oort cloud links

http://www.nineplanets.org/kboc.html

http://zebu.uoregon.edu/~js/glossary/oort_cloud.html

http://www.sky-watch.com/links/oort.html

http://www.answersingenesis.org/docs2001/0221oort_cloud.asp

http://www.creationscience.com/onlinebook/Comets13.html

[Ediacara]

7. thanks

But those last two are a little sketchy...

[Ediacara]

8. One more question

Anyone have a link that explains warp speed as a function of real speeds?

[Senjutsu]

9. Wikipedia

Warp Speeds.

And just for good measure, Oort clouds.

[undergroundpanther]

10. I put the cheeze links in

To cover the spectrum of thought on all sides as best as I could...including the cheezy.

[Ediacara]

13. Cool :-)

No problem, and thanks again!

[Ediacara]

12. Can someone check my math here?

Assuming the Universe is 10B ly across, and the comets have been travelling for 10Ka, and that a light year is about 9.5 trillion km....

Comets would have to travel:

95,000,000,000,000,000,000 km/y

And given that there are (please check this too):

31,536,000 s/y

Then that means that these comets would have to move:

3,012,430,238,457 km/s

OR SIX TIMES FASTER THAN WARP 9.9999!!!!!!

ON EDIT: to expand the linnear dimensions of the universe by one billion LOL.

ON EDIT AGAIN: to add that (assuming c is around 300,000 km/s) that this is over 10M c!!!

[Senjutsu]

15. That's a mighty small universe

A 10ly universe?

I;m not really clear what you mean by:

Comets would have to travel:

95,000,000,000,000,000,000 km/y

comets would have to travel that fast to do what, exactly?

[Ediacara]

16. LOL woops

I meant 10B ly,

And by 95Q km/y I mean travelling from the edge of the universe to the solar system.

I want to ask him where new comets come from, if not a fairly close Oort Cloud, and if he still insists Oort claimed the Cloud was at the dge of the universe, I just want a speed estimate.

[Senjutsu]

17. ok

Assuming the Universe is 10B ly across, and the comets have been travelling for 10Ka, and that a light year is about 9.5 trillion km....

Comets would have to travel:

95,000,000,000,000,000,000 km/y

Yes, but that's edge to edge. Presumably our solar system doesn't lie at the end of the 10B ly journey, but somewhere in between.

And given that there are (please check this too):

31,536,000 s/y

Correct.

Then that means that these comets would have to move:

3,012,430,238,457 km/s

OR SIX TIMES FASTER THAN WARP 9.9999!!!!!!

I get 301, 243, 023, 846 km/s (9.5 x 10^22/(10000*31,536,000)).

This assumes that the comet moves from 1 edge of the universe straight across to the other in the incredibly short period of 10,000 annums. It's these two assumptions that are questionable, not so much the math.

[Ediacara]

21. I kep getting 3T and not 300B

Anyone else?

In any case, travelling at 1.5T km/s is hardly slower :-)

According to the formula on the page linked (s = w^(10/3)c), this is warp 102.3, even though, I know, warp speed can't exceed warp 10....

[Senjutsu]

22. You're right, I slipped a digit

Take 95,000,000,000,000,000,000 km/y, multiply by 10,000 years to recover original distance, divide by (10,000 years *
31,536,000 seconds/year) =

3,012,430,238,457 km/s

[nothingshocksmeanymore]

11. Thanks for educating me on this subject tonight Dino Boy

:D

[Ediacara]

14. No problem!

:-)

[soaky]

18. out of interest...

hi DinoBoy,

just out of interest, who is this speaker?

[Ediacara]

20. A fellow named Mace Baker

[pmbryant]

19. Some belated answers

I've perused the other answers and I think I may have a few things to add or to clarify that haven't been mentioned yet, so I'll go ahead and answer your questions myself:

1) Has the Oort Cloud actually been documented and photographed? I know there are plenty of Kuiper objects, but I am uncertain of the Oort Cloud.

It has never been physically seen; its existence is inferred, and is not scientifically controversial at the current time.

2) Did never-before-seen comets, like Hale-Bopp and Hyakutake come directly from the Oort Cloud? Even if the answer is no, I think it would be interesting to hear an explanation of where they came from in his opinion.

These 'never-before-seen' comets are also known as "Long Period Comets". It is these comets that led Oort to hypothesize the existence of the Oort Cloud. Here is an explanation from professional astronomer Dave Jewitt:

http://www.ifa.hawaii.edu/faculty/jewitt/oort.html

The orbits of comets exhibit a wide range of sizes, inclinations and eccentricities. In the past, it was convenient to divide the comets into two groups based on their orbital period. Long-Period Comets (LPCs) are those with period > 200 years, while Short-Period Comets (SPCs) have period < 200 years.

The LPCs have several remarkable orbital properties:

Their orbits are concentrated towards very large sizes.

They enter the planetary region isotropically (i.e. they show no preferred direction). 50% of LPCs are retrograde, consistent with a truly random distribution.

Jan Oort noticed that the concentration towards large orbital size was very tightly peaked. He calculated that comets falling into the solar system from very large distances should suffer perturbations from the planets (especially Jupiter) and found that these perturbations were actually larger than the width of the LPC peak. He reasoned that many of the LPCs must be entering the solar system for the first time, otherwise their orbits would already have been modified by gravitational perturbations due to the major planets. He also noted that the LPCs seem to fall from a distance of about 50,000 AU. Therefore, he suggested that the sun is surrounded by a spherical cloud of comets from which the observed LPCs are somehow perturbed. So good, so far.

3) How big is the universe? I ask this because I may ask him tomorrow where Hale Bopp and Hyakutake came from (well if indeed they are directly from the Oort Cloud), and if he still insists the Oort Cloud (if it exists) is at the end of the universe, well then..... I want a speed estimate (and yes I know, it would be something like Warp 146). I actually think I will put it onto a warp speed scale :-)

The Universe is about 13-14 billion years old, so the visible Universe comprises that size (EDIT: i.e., 13-14 billion light years). Of course, there could be stuff beyond what we can see, so how big the entire Universe is is an unknown question.

--Peter

[Ediacara]

23. Thanks Peter!

Universe edge comets travelling at warp 102.3... Jeez :-)