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Where Does The Solar System End?  
User currently offline2707200X From United States of America, joined Mar 2009, 8793 posts, RR: 1
Posted (2 years 6 months 5 days ago) and read 2384 times:

In the news I have read that Voyager 1 has reached the edge of the Heliosphere and is at the heliopause where the interstellar media and the solar wind balances out.

In the research that I have done I have not been able to find out where the real edge of the solar system is. It was always thought initially that the solar system ended with the orbit of Pluto, then we heard about the Kuiper Belt it made common sense that the edge of the solar system should be extended by definition. Following the discovery of Sedna which has a maximum aphelion of 927 AU and finding out the potential existence of the Oort Cloud extending out some 20,000 AU or 0.32 LY from the Sun.

Unless their is a is a textbook definition on how far the solar system extends I can estimate that the solar system ends where the gravitation of the Sun is to weak to keep an object in orbit and the distance varies depending of the gravitational perturbation effect of other stars. If their is no textbook definition on where the solar system ends, where do you think it should end?


"And all I ask is a tall ship and a star to steer her by." John Masefield Sea-Fever
17 replies: All unread, jump to last
 
User currently offlineDocLightning From United States of America, joined Nov 2005, 20335 posts, RR: 59
Reply 1, posted (2 years 6 months 5 days ago) and read 2382 times:

It ends at whichever excuse the Voyager spacecraft have to celebrate something.

Signed,

-NASA's PR department


User currently offlinesccutler From United States of America, joined Jan 2000, 5615 posts, RR: 28
Reply 2, posted (2 years 6 months 5 days ago) and read 2375 times:

If you've ever driven from LA to Texas, I think you'd agree that it ends at Blythe, California.


...three miles from BRONS, clear for the ILS one five approach...
User currently offlineConfuscius From United States of America, joined Aug 2001, 3875 posts, RR: 1
Reply 3, posted (2 years 6 months 4 days 23 hours ago) and read 2349 times:

Quoting 2707200X (Thread starter):
Where Does The Solar System End? 

Uranus?



Ain't I a stinker?
User currently offlineBMI727 From United States of America, joined Feb 2009, 15831 posts, RR: 27
Reply 4, posted (2 years 6 months 4 days 23 hours ago) and read 2346 times:

It's like asking where your neighborhood ends. Different people will likely have different answers.


Why do Aerospace Engineering students have to turn things in on time?
User currently offlinetrav110 From Canada, joined Jun 2005, 536 posts, RR: 3
Reply 5, posted (2 years 6 months 4 days 22 hours ago) and read 2324 times:

It ends around the point where forces from interstellar winds and the suns radiative pressure equal out. Anything past that point wouldn't be considered part of the solar system.

User currently offlinetugger From United States of America, joined Apr 2006, 5773 posts, RR: 10
Reply 6, posted (2 years 6 months 4 days 22 hours ago) and read 2321 times:

Quoting 2707200X (Thread starter):
Unless their is a is a textbook definition on how far the solar system extends I can estimate that the solar system ends where the gravitation of the Sun is to weak to keep an object in orbit and the distance varies depending of the gravitational perturbation effect of other stars. If their is no textbook definition on where the solar system ends, where do you think it should end?

Google "heliosphere"....

The modern "normal textbook definition" of the solar systems edge is the where the suns energy meets and is matched by the outside cosmic radiation. This is the limit of the solar-wind which fills the heliosphere and the general edge of Sol's influence upon the local environment.

Quote:
The heliosphere is a bubble of charged particles in the space surrounding the Solar System, "blown" into the interstellar medium (the hydrogen and helium gas that permeates the galaxy) by the solar wind. Although electrically neutral atoms from interstellar volume can penetrate this bubble, virtually all of the material in the heliosphere emanates from the Sun itself.

For the first ten billion kilometers of its radius, the solar wind travels at over 1 000 000 km/h. As it begins to interact with the interstellar medium, it slows down before finally ceasing altogether. The point where the solar wind begins to slow is called the termination shock; then the solar wind continues to slow as it passes through the heliosheath leading to a boundary where the interstellar medium and solar wind pressures balance called the heliopause. In situ data from the Voyagers suggest the heliosheath has magnetic bubbles and a stagnation zone.

[....]

A 'stagnation region' within the heliosheath, starting around 113 AU, was detected by Voyager 1 in 2010. There the solar wind velocity drops to zero, the magnetic field intensity doubles, and high-energy electrons from the galaxy increase 100-fold. Starting in May 2012 at 120.5 AU, Voyager 1 has also detected a notable increase in cosmic rays, an apparent signature of approach to the heliopause.
http://en.wikipedia.org/wiki/Heliosphere

It is sort of equivalent to the magnetosphere of the earth.

You could argue that Sol's gravity affects more beyond the heliosphere and so the edge should be where that gravitational influence ends which is fine but technically gravity's influence never ends, the mass's influence just grows weaker the further away you get from the body.

Tugg



I don’t know that I am unafraid to be myself, but it is hard to be somebody else. -W. Shatner
User currently offlineDocLightning From United States of America, joined Nov 2005, 20335 posts, RR: 59
Reply 7, posted (2 years 6 months 4 days 21 hours ago) and read 2280 times:

Quoting tugger (Reply 6):
You could argue that Sol's gravity affects more beyond the heliosphere and so the edge should be where that gravitational influence ends which is fine but technically gravity's influence never ends, the mass's influence just grows weaker the further away you get from the body.

At that point, you would have to ask when the gravitational force of the sun is overwhelmed by the background gravitational field of the galaxy, which is the definition of the "end of the solar system" that I've heard. There is also the bow shock region, which could also be considered the edge of the solar system.


User currently offlineeinsteinboricua From Puerto Rico, joined Apr 2010, 3367 posts, RR: 8
Reply 8, posted (2 years 6 months 4 days 17 hours ago) and read 2198 times:

Considering that Solar System refers to all bodies under the Sun's influence, I'd say it's just until the heliopause (where Solar and interstellar energy are in balance). I guess it also depends on your perspective. Many say Solar System and refer exclusively to the planets; some take it further and include Pluto; some continue on to the Kuiper Belt, the Scattered Disk, the Oort Cloud, and beyond.


"You haven't seen a tree until you've seen its shadow from the sky."
User currently offlinevarigb707 From , joined Dec 1969, posts, RR:
Reply 9, posted (2 years 6 months 4 days 17 hours ago) and read 2185 times:

Quoting 2707200X (Thread starter):
Where Does The Solar System End?  

Science & Technology Updated: June 9, 2011, 5:49 p.m. ET
At the Far End of the Solar System: Space Bubbles
Some 10 billion miles from Earth, the decades-old twin Voyager spacecraft have beamed back new data that show frenzied bubbles near the edge of our solar system.

The twin Voyager spacecraft have beamed back a set of data that reshape our understanding of what's happening at the farthest edges of our solar system.

The farther the magnetic field extends out from the sun, the weirder it behaves, the study suggests.

At the far end of the solar system is the heliosphere, a tunnel created by solar wind. Both Voyager spacecraft are in the heliosphere's outermost layer now, the heliosheath, where that solar wind is slowed by high-pressured interstellar gas. Data suggest that inside the heliosheath is a sea of frenzied bubbles, sausage-like in shape, each bubble about 100 million miles wide. That's roughly the same as the distance between the earth and the sun.

Merav Opher, a Boston University astronomer and the study's lead author described it as "a really agitated Jacuzzi."

The theory is based on computer modeling that analyzed electron readings from the Voyager spacecraft. Readings had found dips and swells in the amount of electrons encountered by the two spacecraft. The models indicate these variations were caused by the spacecraft moving in and out of the bubbles.

The bubbles are believed to be part of the sun's magnetic field: charged particles of ionized gas, which stretch and twist as they move out toward the edge of the solar system and into the heliosphere. They are caused by lines of magnetic force explosively reorganizing themselves, scientists say. The findings were released Thursday in the Astrophysical Journal.

"We're pretty confident [data] is telling us that there is a major change in the structure of the magnetic field," Opher said.

Scientists ultimately want to know what happens when galactic cosmic rays and other subatomic particles from interstellar space enter our solar system via the heliosphere. "We still have to explore the details of how the galactic rays will get across the heliosphere, and how they're going to wander through those bubbles," said James Drake, a University of Maryland physics professor.

The bubbles cause no danger for those living on earth and no danger for the spacecraft, scientists say. "But if you're headed to Mars, you really do have to care about the radiation environment in the heliosphere," said Eugene Parker of the University of Chicago.

After 33 years charging through the solar system, the two Voyager spacecraft are now about 10 billion miles from Earth. Both spacecraft contain instruments that measure energetic particles and send that data back to Earth.

Next step, Opher said, is to send better instruments out to interstellar space. "Voyager was designed in the late '60s with wonderful instruments," she said. "But we need more sensitive instruments. We're just scraping the surface of how sensitive is the heliosheath."



User currently offlineconnies4ever From Canada, joined Feb 2006, 4066 posts, RR: 13
Reply 10, posted (2 years 6 months 4 days 15 hours ago) and read 2133 times:

Quoting sccutler (Reply 2):
If you've ever driven from LA to Texas, I think you'd agree that it ends at Blythe, California.

   Blythians won't like that but, hey, they're in Blythe.

Quoting trav110 (Reply 5):
It ends around the point where forces from interstellar winds and the suns radiative pressure equal out. Anything past that point wouldn't be considered part of the solar system.

There would still be bodies out there influenced by the Sun's gravitational field, however weak it might be.

Quoting tugger (Reply 6):
You could argue that Sol's gravity affects more beyond the heliosphere and so the edge should be where that gravitational influence ends which is fine but technically gravity's influence never ends, the mass's influence just grows weaker the further away you get from the body.

Per above, agreed. But "mass's influence" ? Please explain. There's inertia, of course.

Quoting DocLightning (Reply 7):
At that point, you would have to ask when the gravitational force of the sun is overwhelmed by the background gravitational field of the galaxy, which is the definition of the "end of the solar system" that I've heard. There is also the bow shock region, which could also be considered the edge of the solar system.

Agreed re gravity. Bow shock traditionally is meant to indicate the region where velocity of any given fluid or medium goes subsonic from supersonic. However IBEX and Voyager data recently interpreted indicates that a solar bow shock may not exist.

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

http://www.sciencemag.org/content/336/6086/1291.abstract

http://www.sciencedaily.com/releases/2012/05/120510141957.htm

http://physicsworld.com/cws/article/...w-shock-no-show-shocks-astronomers

So, it seems that once you get to the heliopause, you're starting to get very close to interstellar space. Perhaps only 10's of AUs. Hopefully for both Voyagers there will not be a toll booth.



Nostalgia isn't what it used to be.
User currently offlinetugger From United States of America, joined Apr 2006, 5773 posts, RR: 10
Reply 11, posted (2 years 6 months 4 days 8 hours ago) and read 2017 times:

Quoting connies4ever (Reply 10):
Per above, agreed. But "mass's influence" ? Please explain. There's inertia, of course.

I am just meaning any planetary or stellar mass (a star typically). The greater the mass the greater its influence on surrounding space. And of course the greater the distance away from the mass the weaker the influence. Yet technically (at least in theory) no matter where they are in the universe, two masses always have some effect on each other. If there were only two objects in the universe, they would interact and (depending on their velocities) slowly over time approach and orbit each other.

Just standard physics.

Tugg



I don’t know that I am unafraid to be myself, but it is hard to be somebody else. -W. Shatner
User currently offlineconnies4ever From Canada, joined Feb 2006, 4066 posts, RR: 13
Reply 12, posted (2 years 6 months 4 days 6 hours ago) and read 1980 times:

Quoting tugger (Reply 11):
I am just meaning any planetary or stellar mass (a star typically).

Ok, thanks for that. Terminology threw me off somewhat.



Nostalgia isn't what it used to be.
User currently offlineAesma From France, joined Nov 2009, 6925 posts, RR: 12
Reply 13, posted (2 years 6 months 1 day 4 hours ago) and read 1779 times:

When another star is having more gravitational pull than the Sun ?


New Technology is the name we give to stuff that doesn't work yet. Douglas Adams
User currently offlinehOMSAr From United States of America, joined Jan 2010, 1211 posts, RR: 0
Reply 14, posted (2 years 6 months 1 day 3 hours ago) and read 1766 times:

I suppose now would be a bad time to point out that Voyager left its wallet at home.


I was raised by a cup of coffee.
User currently offlineeinsteinboricua From Puerto Rico, joined Apr 2010, 3367 posts, RR: 8
Reply 15, posted (2 years 6 months 1 day 3 hours ago) and read 1758 times:

Quoting Aesma (Reply 13):
When another star is having more gravitational pull than the Sun ?

He asked where. Second of all, stars can only have so much influence over an area. With billions and billions of miles between them, there is sure to be a point where interstellar gas dominates an area and no star has influence over the objects between them. In this case, after the heliopause, interstellar winds are stronger and the Sun no longer influences objects. In theory, the solar system ends when the Sun's total influence ends and interstellar winds take over.



"You haven't seen a tree until you've seen its shadow from the sky."
User currently offlineDocLightning From United States of America, joined Nov 2005, 20335 posts, RR: 59
Reply 16, posted (2 years 6 months 1 day 1 hour ago) and read 1729 times:

Quoting einsteinboricua (Reply 15):
He asked where. Second of all, stars can only have so much influence over an area. With billions and billions of miles between them, there is sure to be a point where interstellar gas dominates an area and no star has influence over the objects between them. In this case, after the heliopause, interstellar winds are stronger and the Sun no longer influences objects. In theory, the solar system ends when the Sun's total influence ends and interstellar winds take over.

There is a background gravitational field of the galaxy, and there is certainly a point where the gravitational field of the nearest star becomes as strong as the sun's. I would argue that at those points, the sun would have no influence other than its paltry light.

The Oort cloud is definitely part of the solar system, but it is thought to extend out perhaps one or two light years from the sun. It is disingenuous to argue that you are in interstellar space when you are still passing objects that are orbiting the sun.


User currently offlineMax Q From United States of America, joined May 2001, 4778 posts, RR: 19
Reply 17, posted (2 years 6 months 1 day ago) and read 1718 times:

Just look for the sign




'you are now leaving our solar system'



The best contribution to safety is a competent Pilot.
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