Oort Cloud

[BenConway]

is there really a bubble around our solar system (which are the remains of a planetary nebula)?

[BenConway]

i just simply dont think there is one as it would probably distort astronomers views of objects outside our solor system.

[symesie04]

The Oort cloud as far as im aware is a mass of debris (mainly comets) that surround our solar system. Its a long way out and despite the huge number of comets estimated they would be so spread out covering a vast distance that they would not obscure views.

[Planetesimal]

What Symesie said. The Oort cloud is a vast, sparse region of comets surrounding the Sun. It's almost empty, but it's there just the same. It's thought to extend out from the Sun as much as two light-years, so you can imagine that even with a lot of comets there aren't enough of them to obscure the view. Perhaps the issue is with the word "cloud". Think of it more like a cloud of dust motes that you sometimes glimpse at home in a ray of sunshine coming through the window. The dust doesn't impede your view out the window at all, but there's lots of it there nonetheless. The Oort cloud is a bit like that but much more sparse.

[symesie04]

Im sure wiki can explain it far more eloquently than i and is actually quite an interesting read.

http://en.wikipedia.org/wiki/Oort_cloud

[BenConway]

yes but it is still hyperthetical. Im sure when andromeda passes through we will find out

[symesie04]

Yes it is hyperthetical but appears to fit with computer modelling of the formation of planetary systems and also with the origins of long period comets. Considering its agreement with such observations im not sure why it is still a hypothesis and not a theory. But either way much of astro physics is theory or hypothesis.

[VigdisVZ]

I love the new frontiers of the Oort cloud and the Kuiper belt. I know these are just theories and will proably turn up as false, but I like the possibility of cold stars and dark gas giants hiding just out of view at the frozen edge of interstellar space.

http://en.wikipedia.org/wiki/Nemesis_(hypothetical_star)

http://en.wikipedia.org/wiki/Tyche_(hypothetical_planet)

[goodricke1]

http://en.wikipedia....othetical_star)

Well I love the way you have to read it all through until the last line tells you the whole article is rubbish

[Treeden]

... Think of it more like a cloud of dust motes that you sometimes glimpse at home in a ray of sunshine coming through the window. The dust doesn't impede your view out the window at all, but there's lots of it there nonetheless.

I like that. Excellent analogy, thank you.

[Mr Q]

Speaking of the Ort Cloud, there is presently a space probe with an infrared scope looking for a possible binary companion to our Sun presently near or in the Ort Cloud. This companion has a very eliptical orbit that is close to our Sun at its closest and into the Ort Cloud at its farthest. It's

believed that this companion is a red dwarf (too faint to be seen from Earth) and has been interacting with many comets with gravitational forces that have sent some comets to the inner solar system (the one believed responsible for the extinction of the dinosaurs). Its orbit takes many millions of years to complete and it has been given the name "Nemisis". Untill the probe finds this companion, the existance of Nemisis is purely theoritical.

[symesie04]

I dont get that. Red Dwarfs are observable from Earth, in fact 20 of the 30 closest stars to earth are red dwarfs. Maybe not visible to the naked eye from earth. Either way the Oort cloud is thought to extend to around 1ly from the sun which is much closer than any of the red dwarfs thus far spotted so i really dont understand why this one has yet to be. Would this be the object of Myan domesday by any chance?

[Planetesimal]

Just right symesie. Our nearest star, Proxima Centauri, is a red dwarf, and that's over 4 light years away. I can see it in my 6" reflector.

Yeah, the Mayans are definitely at it again! I hope nobody seriously expects to be going to SGL8, what with the world ending in December and all...

[Mr Q]

I dont get that. Red Dwarfs are observable from Earth, in fact 20 of the 30 closest stars to earth are red dwarfs. Maybe not visible to the naked eye from earth. Either way the Oort cloud is thought to extend to around 1ly from the sun which is much closer than any of the red dwarfs thus far spotted so i really dont understand why this one has yet to be. Would this be the object of Myan domesday by any chance?

Like any spectral class of any star, a red dwarf can vary in temperature - thus its visibility - the cooler ones can be invisible to the eye (even in a scope) but still radiate in the infrared, like this one is supposed to do. No, it has nothing to do with the Mayan prophesy.

Maybe the term red dwarf in the program could have been better used as brown dwarf?

[symesie04]

Hmmm seems WISE disagrees with your program. Think i know which one my money would be on Unless of course your suggesting that this red dwarf is fainter then the brown dwarfs thus far discovered?

http://www.jpl.nasa.gov/news/news.php?release=2012-164

[Mr Q]

Hmmm seems WISE disagrees with your program. Think i know which one my money would be on Unless of course your suggesting that this red dwarf is fainter then the brown dwarfs thus far discovered?

http://www.jpl.nasa....elease=2012-164

Like any TV program, you have to expect some misinformation due to a serious lack of research on the subject. Debating whether it is a red or brown dwarf misses my original point, which is a theory to possibly explain how some comets in the Ort Cloud do end up making journeys close to our Sun and possibly hitting the Earth sometime in the past. The results of the infrared telescopic probe search could support or disprove the "Nemisis" theory. Time will tell.

[JulianO]

The results of the infrared telescopic probe search could support or disprove the "Nemisis" theory. Time will tell.

It can only support the theory. If it doesn't find anything, then it's always possible it's below the detection limit, so like the Lock Ness monster and Russell's teapot it might still exist.

I think I'm fairly definitely in the "Nemesis doesnt exist" camp, but it would be interesting to be proved wrong.

[Earl]

i just simply dont think there is one as it would probably distort astronomers views of objects outside our solor system.

If the said cloud is very low density it will probably make little difference, bit like muck on a mirror, there has to be lots to make any visible difference

[Ronnie67]

The Oort cloud is a hypothesized spherical cloud of comets which may lie roughly 50,000 AU, or nearly a light year, from the Sun. This places the cloud at nearly a quarter of the distance to Proxima Centauri, the nearest star to the Sun. The Kuiper belt and the scattered disc, the other two reservoirs of trans-Neptunian objects, are less than one thousandth of the Oort cloud's distance. The outer limit of the Oort cloud defines the cosmographical boundary of the Solar System and the region of the Sun's gravitational dominance.

The Oort cloud is thought to comprise two separate regions: a spherical outer Oort cloud and a disc-shaped inner Oort cloud, or Hills cloud. Objects in the Oort cloud are largely composed of ices, such as water, ammonia, and methane.

http://en.wikipedia.org/wiki/Oort_cloud

[Budding Star Gazer]

i very much doubt it but it would be cool if voyager continued to run to 50,000 AU and sent back information that there is more to our solar system than we realised.

it's just on the verge of leaving our solar system where they expect the suns reach to end and break into interstellar space.

wouldn't this be the definative edge of our solar system ? if the Oort cloud is there would this then be the definative edge of our solar system.

http://voyager.jpl.nasa.gov/

still our greatest achievement.

[Cath]

IF we are in a binary star system then I'm guessing 'close' means far father away than what our planrts are. Otherwise the planets orbits would have been badly affected time and time again, which I presume would mean no life on planet Earth.

[J_M_Franklin]

Couple of points on this thread;

• The Oort cloud is more than just theory, the majority of long period comets all have their perihelion points in the region between 30,000 and 60,000 AU from the Sun, implying that there is a reservoir of material at the this region and very occasionally some of this ends up in trajectories that brings them into the inner solar system. Investigations of other planetary systems show that the majority of stars have scattered disks and outer regions that resemble the proposed Oort Cloud in several ways.
  
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• A Red Dwarf in a million year long orbit about the Sun would be difficult to tell from the background stars because it would travel such a slow distance across the sky and would be difficult to separate from background stars.
  
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• The "wobble" of the Sun has been all but accounted for and whilst there are discrepancies that leave open the possibility of larger worlds beyond the current crop of outer solar system dwarf planets, these discrepancies are insufficient to account for a body even as large as Jupiter let alone a Dwarf Star...