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Question: Orientation of Solar System to Galactic Plane

  • A number of years ago I read somewhere that the plane of the solar system is oriented around 90 degrees to the galactic plane.  That can't be right -- the geometry just doesn't work.  So, how is the plane of the solar system oriented to the galactic plane?

  • Welcome to the discussion group, davidh.

     

    Actually the two planes intersect at an angle of about 60°.

     



    [edited by: Centaur at 06:10 PM (GMT -6) on Feb 09, 2008]

    For astronomical graphics, including monthly wallpaper calendar, visit:

    CurtRenz.com/astronomical

    Curt Renz - "Centaur"

  • But that would make the central regions of the galaxy only visible from one hemisphere, likewise the outer regions would be visible only to the other hemisphere.  Perhaps it is the yaw that is 60 degrees, but I would think the pitch would be fairly close to the galactic plane.

  • The central region of the galaxy is in the direction of the constellation Sagittarius and not far from Scorpius.  It is near them that the plane of the galaxy intersects the ecliptic (plane of Earth’s orbit) at an angle of about 60°.  If the planes were nearly parallel, then we would see the Milky Way running through all of the constellations of the zodiac. 

     

    Picture a summer evening while the region between Sagittarius and Scorpius is crossing your southern meridian.  The ecliptic would appear parallel to the horizon.   You would observe the Milky Way sweeping upward at an angle of about 60° to the ecliptic.

    You mention the Earth’s hemispheres, but they are separated by the Earth’s equatorial plane, not the ecliptic or galactic planes.  The equatorial plane currently intersects the ecliptic plane at more than 23°.  In the current era, the center of the galaxy is visible from the Earth’s South Pole and not the North Pole.  That will eventually reverse due to precession.  But in either case, observers on most of the Earth’s surface experience periods of the day during which the galactic center is above the horizon. 

     



    [edited by: Centaur at 10:53 AM (GMT -6) on Feb 10, 2008]

    For astronomical graphics, including monthly wallpaper calendar, visit:

    CurtRenz.com/astronomical

    Curt Renz - "Centaur"

  • Hello and many thanks for useful explanation, however.....as a picture tells a thousand words, and rather than re-inventing the wheel,  does anyone know of any website which would display the Earth's tilt and orbit within Solar System, within the Solar System's tilt and orbit around  MW,  in one diagram  ?

    If at all possible a winter and a  summer  view for Northern Hemisphere  and same for Southern Hemisphere.

    Many grateful thanks, Avionna

     

    H.D.  Thoreau :  "  Why should I feel lonely !  Isn't our planet in the Milky Way ?  "

  • A good explanation by James B. Kaler is here. His book The Ever Changing Sky has diagrams that will help, but I haven't found similar diagrams online.

    The illustration below (from the European Southern Observatory) dipicts the plane of the Solar System inclined 60 degrees relative to the plane of the Milky Way. It certainly is not to scale, and it shows the Sun centered in the Milky Way (which it certainly is not).

    A photo-realistic interpretation of these alignments is not possible, because the disc of the Milky Way is thousands of times thicker than the Solar System is wide and the diameter of the Milky Way 50,000 to 100,000 times that of the Solar System.

    So, the only accurate thing about the image is the rough angle between the two planes ...

    A modern celestial globe is often clear plastic, with the earth depicted as a ball in the center and the stars, the ecliptic, and the band of the Milky Way shown on the outer clear sphere. The one shown below is an illuminated world globe that when illuminated in a darkened room shows the band of the Milky Way (the cross-hatched pattern) against the pattern of stars and constellations we call the 'celestial sphere' ...



    [edited by: chipdatajeffB at 07:49 AM (GMT -6) on Jul 04, 2010]

    The universe is not only stranger than we imagine, it's stranger than we CAN imagine. --- JBS Haldane

    Come visit me at Comanche Springs Astronomy Campus (we're on Google Maps) in Texas.

    www.3rf.org

  • It might be noted that planets revolve around the Sun in a somewhat retrograde direction relative to that of the stars’ movement around the galactic center.  That means what I earlier called a 60° intersection of the ecliptic with the galactic plane might more accurately be described as 120°. 

     

    The IAU designates a point in the northern celestial hemisphere in Coma Berenices at RA 12:51.4 & Dec N 27°07’ (J2000.0) as the North Galactic Pole.  However, due to the generally retrograde motion of the galaxy relative to the Earth’s rotation, that point on the celestial sphere might be better described as the South Galactic Pole.



    [edited by: Centaur at 02:10 PM (GMT -6) on Jul 04, 2010]

    For astronomical graphics, including monthly wallpaper calendar, visit:

    CurtRenz.com/astronomical

    Curt Renz - "Centaur"

  • A diagram showing the solar system's orientation with respect to the Milky Way can be seen here.

    Dave Mitsky

    Chance favors the prepared mind.

    Fere libenter homines id quod volunt credunt.

    A man is a small thing, and the night is very large and full of wonders.

  • Now THAT is cool! Thanks, Dave!

    The universe is not only stranger than we imagine, it's stranger than we CAN imagine. --- JBS Haldane

    Come visit me at Comanche Springs Astronomy Campus (we're on Google Maps) in Texas.

    www.3rf.org

  •  

    Many grateful thanks for all the replies - it all makes a lot of differences to being able to  " visualise " for explaining........... without the hands going in all directions.

    Cordialement

    Avionna

    (Any more info in that style will be welcome.)

    H.D.  Thoreau :  "  Why should I feel lonely !  Isn't our planet in the Milky Way ?  "

  • A comment Dave Mitsky made in a reply to another thread today, made me recall that an image showing the band of the Milky Way along with the zodiacal band would show this relationship. The link in the previous sentence is to an excellent Web page, with images and an illustration, by Doug Zubenel.

    Here's an all-sky image by Laurent Laveder :

     

    The Milky Way extends from upper left of center to lower right. The zodiacal band is fainter, extending from just right of center at top, to lower left (about 7 o'clock).

    The zodiacal band is sunlight reflecting from dust in the plane of the Solar System, and extends about +/- 16 degrees either side of the path of the Sun through the sky (hence, it brackets the plane of the Solar System).

    In this photo you can clearly see the angle between the starry band and the dusty band.

     



    [edited by: chipdatajeffB at 02:44 PM (GMT -6) on Jul 16, 2010]

    The universe is not only stranger than we imagine, it's stranger than we CAN imagine. --- JBS Haldane

    Come visit me at Comanche Springs Astronomy Campus (we're on Google Maps) in Texas.

    www.3rf.org

  • Thanks for posting that, Jeff.  I'd seen Doug's image before but Laurent's was new to me.

    Dave Mitsky

    Chance favors the prepared mind.

    Fere libenter homines id quod volunt credunt.

    A man is a small thing, and the night is very large and full of wonders.

  • One good idea begets another ... Smile,Wink, & Grin

    Laurent's Web site is here. If you click on the Search box ("rechercher") and enter "Zodiacal" you'll find several dozen nice images of the zodiacal light and zodiacal band.

    Edit: Oops! Thanks, Oliver ... I fixed it!



    [edited by: chipdatajeffB at 11:26 AM (GMT -6) on Jul 17, 2010]

    The universe is not only stranger than we imagine, it's stranger than we CAN imagine. --- JBS Haldane

    Come visit me at Comanche Springs Astronomy Campus (we're on Google Maps) in Texas.

    www.3rf.org

  •  Jeff, that just links to the image again.

  • Hi, thanks again, many good info  since my question.

    Does anyone know of a constructed diagram with 4 intersecting orbital plane : MilkyWay, Sun, Earth ,  Moon.

    I have tried a mixture of words, a change of order of words in Google  but I only have found some websites with only 2 planes  and  I would like the "grand encompassing " view in one picture.

    Many thanks

    Cordialement

    Avionna

    H.D.  Thoreau :  "  Why should I feel lonely !  Isn't our planet in the Milky Way ?  "