What is our Solar System's orbital plane around the Milky Way?

In summary, the conversation discusses various theories and speculations about the orbit of our solar system around the center of the Milky Way galaxy. The concept of the galactic plane is explored, as well as the possibility of a wobble in the solar system's orbit. The idea of crossing the galactic plane and its potential effects on Earth is also mentioned. There is also a brief discussion about the accuracy of determining our position in the galaxy and the properties of the galaxy's black hole. Finally, the theory of the end of the world in 2012 is mentioned but dismissed as unfounded.
  • #1
Chaos' lil bro Order
683
2
Does anyone know a good link to an animation or nice diagram showing how our solar system orbits the center of our milky way? I always imagined the milky way's plane, where most of the material is accumulated, as a record, granted, with a bigger bulge and 2/3 out from the center of that record, lies our solar system. Next, I imagined our solar system, which spins around the milky way's center, much like the record spinning. Then, I wondered if there was a wobble in the record and would this wobble give our solar system a secondary orbit as it wobbles up and down, passing through the milky way's plane. This lead to me thinking about how strong the gravity of the plane was at its center and where our solar system currently was on the wobble, in relation to the galactic plane. Next I thought about late 2012, when, astronomers confirm our solar system will pass through the center of this plane. Then, I considered how the sun and our moon effect tidal forces inside the Earth's core and its oceans. Then I thought about global climate change. Finally, I wondered if bovine and automobile flatulence was more powerful then the mass of our entire galaxy, even if it was... far... far... away.
 
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  • #2
The ridiculous thing about 'crossing the galactic plane' is how you even define the plane. With 3 trillion stars, uncountable number of planets, lots of dust clouds and possibly a black hole in the middle, all of which are constantly moving in different directions, how o you say exactly when you cross the middle of it?
 
  • #3
Chaos' lil bro Order said:
Next I thought about late 2012, when, astronomers confirm our solar system will pass through the center of this plane.

This is utter, complete and total rubbish. Please produce a source for this where a reputable astronomer says this. If you can find one, I'll apologize.

Chaos' lil bro Order said:
Finally, I wondered if bovine and automobile flatulence was more powerful then the mass of our entire galaxy, even if it was... far... far... away.

Great ghu! Don't you have anything better to do than to post such tripe?
 
  • #4
hahaha you enjoyed reading my 'tripe' thoughts, didn't you.

Anyhow I've no problem admitting that it could all be crap. So do astronomers have any sense of our solar system's orbit in the milky way? Here is a link to a survey project that 'seems' to consider the galactic plane, at least for the purposes of their survey, about 5 degrees in width. Admittedly however, there is no clear cut definition of the galactic plane.

Still its a very interesting 1 page read with great diagrams and you will enjoy it. Cheers.

http://www.ras.ucalgary.ca/CGPS/where/

Here is a model of our galaxy created by Cardiff University, UK, confirming my earlier post about 'wobbling'. At least, their model agrees, but I'm not sure its true of accredited by other experts.

http://www.cardiff.ac.uk/news/articles/did-the-solar-system-bounce-finish-the-dinosaurs.html


A visualization of the plane, still, with no defined boundari's unfortunately.

http://apod.gsfc.nasa.gov/apod/ap011020.html
http://www.cardiff.ac.uk/news/articles/did-the-solar-system-bounce-finish-the-dinosaurs.html

Upon further reading I have found that in fact, its believed that our solar system has been in the galactic plane since 1998 and so 2012 would be just another year in the plane. However, since no one ever defines the boundary of this plane, from what I've read, this is somewhat meaningless.
 
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  • #5
The "galactic plane" is a man-made reference and not a physical thing. I don't know the accuracy of the determination in the Canadian survey (your first link), but due to the size (thickness) of the galaxy and speed the solar system moves around it, there would be no noticeable year-to-year change in our position. The galaxy isn't like Saturn's rings, which are all on an extremely narrow plane.

Also, "the gravity of the plane" (from your first post) is meaningless. The Earth is in orbit around the galaxy center of mass and passing through a region of higher density of stars (say...moving wrt the spiral arms...) doesn't change anything. Freefall is freefall.
 
  • #6
They recently discovered that our galaxy is twice as thick as what was previously thought, which is a pretty big discrepancy.
So I would assume we're not actually very close to accurately calculating our true position in the galaxy?
 
  • #7
russ_watters said:
The "galactic plane" is a man-made reference and not a physical thing. I don't know the accuracy of the determination in the Canadian survey (your first link), but due to the size (thickness) of the galaxy and speed the solar system moves around it, there would be no noticeable year-to-year change in our position. The galaxy isn't like Saturn's rings, which are all on an extremely narrow plane.

Also, "the gravity of the plane" (from your first post) is meaningless. The Earth is in orbit around the galaxy center of mass and passing through a region of higher density of stars (say...moving wrt the spiral arms...) doesn't change anything. Freefall is freefall.

Thank you Russ,

What is the prevalent theory on the properties of the Milky Way's BH? Is it possible for a BH to have a poles like a neutron star, that throw ejecta in 2 well defined regions out from both poles? I'm thinking like a GRB or something, but I'm not sure if the mechanics of a BH allow for such a possibility, or if BH's always radiate uniformly, or something else perhaps.

Cheers.

PS Hi Vanadium-50
 
  • #8
I seen something like that on DISCOVERY about Notre Damas predicting the end of life as we know it in 2012. Yeah what ever. It's suppose to end every decade and I am still here, but the discovery show went something like this, i.e. 26,000,000 years to orbit the galaxy, 13,000,000 years to orbit half way around, supposedly were coming up on the half way around point, coming up on the bar in the center of the galaxy and all chaos is suppose to break loose cause of the pull from our galaxy. Its got something to do with the MAYA and there calendar and where our solar system is at in space in our galaxy. I think if you go here you will see some of it, I only seen part of it, so I might be off on some of it. There trying to get it straightened out at least.

http://www.december212012.com/articles/news/Apocalypse%20in%202012.htm

They even sell shelters for 2012. If the world is going to end, I don't think the shelter will help any. LOL
This is what happens when something is put on T.V.
 
  • #9
It actually takes nearer 300M years to orbit the galaxy.
We do not cross the bar or anything like that - we cross an arbitrary meridian plane drawn near the middle of the galaxy. It's not even in the middle because it was based on older surveys (which is why the centre of the Galaxy isn't at 0,0 )

As I said in the earlier post it's like assigning some mystical significance to the centre of the USA but not saying if you are including Alaska, or which offshore islands.

Coincidentally the Maya calendar wraps around in 2012, the unix time_t reaches 1234567890 in about a week, and the shelf my DVDs are on is going to be full by my birthday - none of these signal the end of the world.
 
  • #10
dj1972 said:
I seen something like that on DISCOVERY about Notre Damas

Nostradamus.

Which is sort of indicative of the accuracy of the claims of doom and destruction.
 
  • #11
Hey I was just saying I seen something about it on Discovery. The original question was "Next I thought about late 2012, when, astronomers confirm our solar system will pass through the center of this plane" and someone else said something about Discovery channel. I was just saying I seen it on there, I don't agree with, I just seen it. And I said I might be off on some of it, I didn't watch the whole episode. Oh and thanks for correcting my "Nostradamus". LOL
 
  • #12
mgb_phys said:
It actually takes nearer 300M years to orbit the galaxy.
We do not cross the bar or anything like that - we cross an arbitrary meridian plane drawn near the middle of the galaxy. It's not even in the middle because it was based on older surveys (which is why the centre of the Galaxy isn't at 0,0 )

As I said in the earlier post it's like assigning some mystical significance to the centre of the USA but not saying if you are including Alaska, or which offshore islands.

Coincidentally the Maya calendar wraps around in 2012, the unix time_t reaches 1234567890 in about a week, and the shelf my DVDs are on is going to be full by my birthday - none of these signal the end of the world.

Hi mgb,

What is the angular velocity we orbit the galaxy at? 300M years you say and we're 2/3 out from the milky's center and our diameter is 100,000 LY wide?

How fast do we move?

Cheers
 
  • #13
Chaos' lil bro Order said:
Hi mgb,
What is the angular velocity we orbit the galaxy at? 300M years you say and we're 2/3 out from the milky's center and our diameter is 100,000 LY wide?
How fast do we move?
Assuming values given by the famous astronomer Eric Idle.

https://www.youtube.com/watch?v=buqtdpuZxvk

The Sun's orbit around the galaxy is about 220 km/s the distance to the centre is about 30,000lyr
so its orbital period is actually about 240 million years.
 
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  • #14
Quoting mgb:The ridiculous thing about 'crossing the galactic plane' is how you even define the plane. With 3 trillion stars, uncountable number of planets, lots of dust clouds and possibly a black hole in the middle, all of which are constantly moving in different directions, how do you say exactly when you cross the middle of it?

-Yes, this was my first response when I heard all this stuff about crossing the galactic plane. If I draw a line in the sand and cross it, will my world end? [It's so theoretical/imaginary/difficult to pin point.]

But I am as clueless as the dude who was talking about 'Notre Damas.' [Hey, before any of us heard or read about Nostradamus we didn't have a clue either, so let's not be snobs here even if we sometimes have some fun and amusement. A few centuries from now there will probably be millions of physicists and astronomers laughing at how clueless we currently are and pointing out the mistakes we now see as scientific gospel. None of us were born knowledgeable; we learned what we know from others.]

So my clueless question to someone knowledgeable about this is: why are some stating that the solar system is several dozen light years north of "the galactic plane" and moving away from it while others are stating that it has been moving through the plane from 1998 to 2016 (at center peak in 2007)? Is this bunk or are they talking about two different points of references that are being confused with one another and distorted? Assuming our imaginary plane in the "center" of the galaxy was "accurate," is one true and the other false? Or are they both false?

Conversely are they both relatively true (assuming our imaginary plane is quantifiable) but simply talking about two different phenomenon. [I am familiar with the precession of the equinoxes and the Earth "wobbling like a top," the "26,000 year rotation," and have heard discussions about this motion being confused with the "solar system moving through the galactic plane." Even though everybody may be arguing over something imaginary and worthless, I'd still like to know what each one is referring to (if anything) when they talk about several dozen light years away versus happening from 1998-2016. Does anybody know?
 
  • #15
Jennifer: I think mgb's post answers your questions well. The galactic plane simply isn't well-defined. Whereas some people may draw an arbitrary line, call it THE plane, and measure the sun's distance with respect to it, others consider a large area of high stellar density "the plane" and say that the Sun is in the plane.

See this scatterplot: http://staff.argyll.epsb.ca/jreed/math9/strand4/scatterplot1.gif. Imagine that each of those points represents a star. I want you to indicate the galactic plane. Will you draw an infinitely thin line? If so, where? If I draw a line 0.1 mm above yours, who's wrong and who's right? Will you draw a 1-mm-wide line and say everything the line covers is the galactic plane? But why 1 mm, and not 1.5 mm, or 2 mm? I should say that if those points really do represent stars in the Milky Way, a difference of 0.5 mm represents hundreds of light years.
 
  • #16
Thank you, ideasrule, for the confirmation and the scatterplot. Is it safe to say then that reports about the solar system being several dozen light years north of the galactic "plane" (or having just been passing through it from 98 to 2016)...are basically gibberish? Or are we missing something? Has something floating around been misinterpreted?
[floating around the internet, that is, not space]
 
  • #17
Jennifer Wood said:
reports about the solar system being several dozen light years north of the galactic "plane" (or having just been passing through it from 98 to 2016)...are basically gibberish?
The solar system will (or has) pass through the galactic plane.
But it depends if you mean the Galactic plane as defined by the galactic coordinate system (which were based on 100year old observations and are slightly wrong) or the best estimate of the plane as of today or actual plane of the galaxy which constantly changes and we don't accurately measure.

Either way it has no effect on the earth.
 
  • #18
The topic of crossing the "galactic plane", coinciding with the Mayan calendar, and the catastrophe of "world's end in 2012" are a mixed muddling of mythology.

The Mayan calendar comes to an end (in linear counting mode) in 2012. However, the calendar itself is a circle and the Mayans thought in this circular pattern, much the same way astrology and the Chinese calendar are cyclic patterns.

Crossing the galactic plane is speculation, but also a cyclic event. Much is still unknown about the electrical nature of the cosmos as far as "action at a distance". The concern from some theorists is that the "plane" transit is related to our magnetic field shift, which is also a cyclic pattern. Since we've only inhabited this rock as semi-sentient beings for a short time, we have yet to experience that effect first-hand.

Hard data is difficult to find and there is a lack of consensus among those who are "supposed" to know these things...

I'm just a knucklehead...

woolf
 
  • #19
woolf said:
The Mayan calendar comes to an end (in linear counting mode) in 2012. However, the calendar itself is a circle and the Mayans thought in this circular pattern,
It doesn't end it just clocks around a new leading digit (from 12 to 13), it last did this in the 17th century and nothing happened.

Crossing the galactic plane is speculation, but also a cyclic event.
Not speculation, our orbit around the galaxy is inclined - we must cross the plane twice in each rotation.

The concern from some theorists is that the "plane" transit is related to our magnetic field shift, which is also a cyclic pattern.
Apart from the complete lack of any mechanism to link these, the galactic orbit period is 220Myr and very regular.
Magnetic field reversals are not at all regular (and are probably chaotic) but occur at an interval of < 1Myr.

Since we've only inhabited this rock as semi-sentient beings for a short time, we have yet to experience that effect first-hand.
But lots of other species have and don't seem to have been over worried.
 
  • #20
Have you ever looked out into the night sky and seen the Milky Way Galaxy? Did you notice the obvious tilt? It is at a steep angle to the straight line of the horizon. Why? It turns out that our solar system appears to belong to another galaxy that is colliding with the Milky Way. This was recently discovered when scientists were trying to figure out sources for "Dark Matter" that would account for forces we can measure but not see visibly. Using near-infrared a huge sister galaxy circling the Milky Way was discovered. It's called the Sagittarius Dwarf Galaxy,(SGR for short). For those keen on the 2012 data, this is the reason our entry point to the rift, center, heart of the Milky Way is thru Sagittarius. The two collide at this point. This explains why our solar systems is at a angle to the plane of the galaxy and why we dip above and below that center line every 12,000 years or so. After slow, continuous gnawing by the Milky Way, Sagittarius will be whittled down to the point that it cannot hold itself together much longer!
 
  • #21
payne74 said:
Have you ever looked out into the night sky and seen the Milky Way Galaxy? Did you notice the obvious tilt? It is at a steep angle to the straight line of the horizon. Why? It turns out that our solar system appears to belong to another galaxy that is colliding with the Milky Way. This was recently discovered when scientists were trying to figure out sources for "Dark Matter" that would account for forces we can measure but not see visibly. Using near-infrared a huge sister galaxy circling the Milky Way was discovered. It's called the Sagittarius Dwarf Galaxy,(SGR for short). For those keen on the 2012 data, this is the reason our entry point to the rift, center, heart of the Milky Way is thru Sagittarius. The two collide at this point. This explains why our solar systems is at a angle to the plane of the galaxy and why we dip above and below that center line every 12,000 years or so. After slow, continuous gnawing by the Milky Way, Sagittarius will be whittled down to the point that it cannot hold itself together much longer!

There is no evidence for, and quite a bit against the idea that our Solar system was ever a part of the SGR. Any articles that say the contrary are a result of sloppy journalism and misrepresentation.
 
  • #22
Jennifer Wood said:
...So my clueless question to someone knowledgeable about this is: why are some stating that the solar system is several dozen light years north of "the galactic plane" and moving away from it while others are stating that it has been moving through the plane from 1998 to 2016 (at center peak in 2007)? Is this bunk or are they talking about two different points of references that are being confused with one another and distorted? Assuming our imaginary plane in the "center" of the galaxy was "accurate," is one true and the other false? Or are they both false?

Conversely are they both relatively true (assuming our imaginary plane is quantifiable) but simply talking about two different phenomenon. [I am familiar with the precession of the equinoxes and the Earth "wobbling like a top," the "26,000 year rotation," and have heard discussions about this motion being confused with the "solar system moving through the galactic plane." Even though everybody may be arguing over something imaginary and worthless, I'd still like to know what each one is referring to (if anything) when they talk about several dozen light years away versus happening from 1998-2016. Does anybody know?
I don't think they are confusing to separate phenomena, but rather stating the same thing in two different ways. As an example, some might say this…
Chaos' lil bro Order said:
...So do astronomers have any sense of our solar system's orbit in the milky way? Here is a link to a survey project that 'seems' to consider the galactic plane, at least for the purposes of their survey, about 5 degrees in width.
... And conclude that the Earth "is passing through" galactic plane. However, anyone who's taken their first year of geometry will tell you that a plane is 0° in width. Now, the exact location of the galactic plane may not be well known, but it most certainly does exist. The galaxy is rotating, and for all rotating objects there is both axes of rotation and a plane of rotation. Astronomers can have some hazy ideas as to the amount and distribution of mass in the galaxy, and those ideas might even be completely wrong. This could render our calculations as the galaxy's center of mass (as an example) to be completely inaccurate. Nevertheless, the galaxy most certainly has a center of mass. It also has an axis of rotation and a plane rotation.

For those who talk about the "plane of the galaxy" as an actual plane, we can be fairly certain that the Earth has passed through it. For those who use that term to refer to the general area of increased star density of the galaxy, we are passing through it. Just a difference in semantics, I think.
 
  • #23
Amusing. The 26,000 year cycle relative to what? Earth completes a 26,000 year wobble cycle every second, minute, hour, day, month ... etc. It would be an eerie coincidence if Earth's precessional cycle coincides exactly with the frequency the sun crosses the 'galactic plane' Just how often does this happen? I believe an 'alignment' event also occurred in 1998 - so it appears an earth-sun alignment with the plane of the galactic center can occur in as few as 14 years apart. Read between the hoof prints.
 
  • #24
I recall reading that periodic mass extinctions of life may be caused by the sun's orbit of the galaxy, when the orbit crosses through the galactic plane. This crossing of the galactic plane happens every 120 million years, twice during each 240 million year orbit. The greater density of objects in the galactic plane causes gravitationally-induced perturbation of the Oort cloud, which then rains down a comet bombardment on the earth. Since the dinosaurs vanished 65 million years ago, I don't think we will get back to the galactic plane by 2012! Also, I would expect the duration of the crossing to last on the order of a million years, because the galactic plane is 1000 light years thick (galactic diameter is 100,000 light years).
 
  • #25
CosmologyHobbyist said:
I recall reading that periodic mass extinctions of life may be caused by the sun's orbit of the galaxy, when the orbit crosses through the galactic plane.
Except none of them actually match the period /phase of the crossing.
The sun doesn't move in a perfect plane relative to the galaxy, it wobbles above and below it's incline - these wobbles may be linked to extinction events. But if you are free to choose which wobbles you want to include then you can get them to match any sequence of events you like.

Also, I would expect the duration of the crossing to last on the order of a million years, because the galactic plane is 1000 light years thick (galactic diameter is 100,000 light years).
The Sun's inclination to the plane isn't that high - we don't go all the way out of the disk. We are almost in the middle of the 1000 lyr thickness, it's just that we go from a few 10s lyr above a nominal plane to a few 10s lyr below it
 
  • #26
LURCH said:
Now, the exact location of the galactic plane may not be well known, but it most certainly does exist. The galaxy is rotating, and for all rotating objects there is both axes of rotation and a plane of rotation. Astronomers can have some hazy ideas as to the amount and distribution of mass in the galaxy, and those ideas might even be completely wrong. This could render our calculations as the galaxy's center of mass (as an example) to be completely inaccurate. Nevertheless, the galaxy most certainly has a center of mass. It also has an axis of rotation and a plane rotation.
Not sure if we are thinking along the same lines, but, it seems to me there is a sensible definition for "the galactic plane", even if if it's location cannot be measured accurately.

Our galaxy has angular momentum, which determines a rotation axis; the galactic plane would be perpendicular to that axis. Our galaxy also has a center-of-mass, which would lie within the galactic plane.

Since we can in principle specify the plane's orientation as well as a point that it contains, the plane is defined. However, actually measuring the necessary quantities (angular momentum and center-of-mass location) are another matter.
 
  • #27
We do define 'a' galactic plane, it's the basis of the galactic coordinates
It's not quite accurate, for instance the black hole at the centre of the galaxy isn't quite at 0,0

Defining the exact plane is tricky because it becomes a question of which objects you count as being in the galaxy (eg the LMC/SMC) and how far out you include the halo.
 
  • #28
mgb_phys said:
We do define 'a' galactic plane, it's the basis of the galactic coordinates
It's not quite accurate, for instance the black hole at the centre of the galaxy isn't quite at 0,0
Of course, we need to define a plane for the purposes of defining coordinates of celestial objects. Is it accepted practice to refer to it as the galactic plane? Sorry about my ignorance.
Defining the exact plane is tricky because it becomes a question of which objects you count as being in the galaxy (eg the LMC/SMC) and how far out you include the halo.
I concur, one would need to be clear about what objects are included. I myself am unfamiliar with the mass distribution and properties of the halo. And there is the issue of dark matter; do you (or anyone else) happen to know how well it's distribution within the galaxy is known?
 
  • #29
We pick the sun and the centre of the galaxy as two points to give a coord system
http://en.wikipedia.org/wiki/Galactic_coordinate_system

The mass distribution of the galaxy is pretty well known from rotation curves, at least as far out as we can see stars.
The centre of the galaxy is pretty well defined, it helps that there is a couple of million solar mass black hole there! The extent of the galaxy is like defining the edge of the atmosphere - it's pretty wooly.
 
  • #30
Redbelly98 said:
Not sure if we are thinking along the same lines, but, it seems to me there is a sensible definition for "the galactic plane", even if if it's location cannot be measured accurately.

Our galaxy has angular momentum, which determines a rotation axis; the galactic plane would be perpendicular to that axis. Our galaxy also has a center-of-mass, which would lie within the galactic plane.

Since we can in principle specify the plane's orientation as well as a point that it contains, the plane is defined. However, actually measuring the necessary quantities (angular momentum and center-of-mass location) are another matter.
yeah, that's pretty much what I was thinking.
 
  • #31
Dear MGB,

Thanks for the info on sun's journey within galactic disk - you are better than Google! You surprised me when you said we are near the midway point within the disk. A look at the Milky Way or photo of same shows a very obvious half-dome marking the half of the spherical galactic center that shows above the dust lanes; the other half of of the galactic center shows as mostly obscured by dust lanes. Are the dust lanes themselves are below (or above?) the mid-point of the galactic disk?

On the sun passing through the galactic disk, when I Googled that one, the real story is that mass extinctions line up with the one end of the "bar" of our barred spiral galaxy, passing by our sun. Another view is that a spiral arm passes through the area of our sun. The time periods match within 50% margin of error, so its not definitive, but still a possibility. In my original post I didnt want to get mired in all that detail, thanks for calling me on that - I hate laziness!
 
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  • #32
Janus said:
There is no evidence for, and quite a bit against the idea that our Solar system was ever a part of the SGR. Any articles that say the contrary are a result of sloppy journalism and misrepresentation.

The evidence is there for the ideal that our Solar system was a part of SGR. It's sloppy to say that it's misrepresentation! There's still no explanation of why the Milky Way is viewed at a angle in the night sky.
 
  • #33
payne74 said:
The evidence is there for the ideal that our Solar system was a part of SGR. It's sloppy to say that it's misrepresentation! There's still no explanation of why the Milky Way is viewed at a angle in the night sky.
Quote your source and then we will talk.
 
  • #34
This article is about the Sun and its planetary system. For other systems, see planetary system and star system.http://sunrent.de/smileynormal.ico
 
  • #35
Jug of rum - doom and gloom. The solar system is roughly aligned with the galactic plane because it is part of our milky way galaxy. Most stars reside near the galactic plane in all spiral galaxies - shocking. duh.
 

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