Orientation of the Earth, Sun and Solar System in the Milky Way

  • #106
Cataclysmo
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Thanks for your response. Yes the big picture of this thread is in regards to the position of the solar system relative to the mid plane of the Galaxy. I hope this discussion is still relevant and not deviating too far.

I'm focusing in on the celestial plain and lunar plain relative to earth. It seems the celestial plane and lunar plain are tilted in opposite directions leading to the trend of the Moon passing higher through the sky during winter nights and the sun passing lower in the sky during winter days. Yes, like you said longer hours of moonlight in the winter. I'm speaking from a northern hemisphere reference and also I'm curious if this is naturally also applicable for the southern hemisphere? Hope this isn't coming across as a homework question but actually as in sincere curiosity the heavenly bodies.
Kindest Regards
If I may correct my terminology stating the lunar plane and Celestial plane are tilted in opposite directions is not very well worded. Basically I'm just saying the lunar plain is tilted higher than the celestial plain ( speaking from a northern hemisphere Viewpoint near winter solstice). I sure could use a better way to word that.
 
  • #107
sophiecentaur
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I'm curious if this is naturally also applicable for the southern hemisphere?
The Moon's orbit has to around the CM of Earth / Moon so the plane must go through the middle. I think that implies that the effects are the same, top and bottom.
Edit: I think that comment needs to be modified to include the idea of 'average over time'.
 
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  • #108
Janus
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If I may correct my terminology stating the lunar plane and Celestial plane are tilted in opposite directions is not very well worded. Basically I'm just saying the lunar plain is tilted higher than the celestial plain ( speaking from a northern hemisphere Viewpoint near winter solstice). I sure could use a better way to word that.
"Tilted higher" is a bit of an arbitrary statement. The Moon's orbit is tilted at 5 degrees to the ecliptic (the Earth solar orbit plane). The Moon's orbit also has a nodal precession; It "wobbles". The period of this precession is 18.6 years. This, in turn means that the Lunar orbit varies from being 18.5 to 28.5 degrees in tilt with respect to the celestial equator over that 18.6 year period.

While in one year, at the winter solstice, the Lunar orbit will align so that the full moon can appear higher in the Southern sky (as seen from the Northern hemisphere) than the Sun does on the Summer solstice(The difference between maximum and minimum declination will be the greatest), 9.3 years later, the full moon will never get as high in the sky as the Sun does on the Summer solstice (the difference between declinations will be the least).
 
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  • #109
Drakkith
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The Moon's orbit also has a nodal precession; It "wobbles". The period of this precession is 18.6 years. This, in turn means that the Lunar orbit varies from being 18.5 to 28.5 degrees in tilt with respect to the celestial equator over that 18.6 year period.

Whoa! That's a lot of wobble! I had no idea the Moon's orbit varied its tilt by 10 degrees.
Any idea where we are in the cycle now?
 
  • #110
phyzguy
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Whoa! That's a lot of wobble! I had no idea the Moon's orbit varied its tilt by 10 degrees.
Any idea where we are in the cycle now?

The moon's orbit is always inclined by 5 degrees relative to the ecliptic plane. It's just that as it precesses, the inclination to the Earth's equatorial plane ranges from 23.5-5=18.5 to 23.5+5=28.5.
 
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  • #111
Cataclysmo
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Thank you for the feedback I enjoy being an ambassador of this knowledge to my friends and family. Two nights ago we were at the beach early in the morning and I was describing the beginning of the perseid meteor shower when we saw a red fiery meteor shoot overhead. It was about a spaghetti noodle wide with a tail about 20 degrees in arc length. I will study the main thread further.
Cheers.
If your plan is for one year plant rice. If your plan is for ten years plant trees. If your plan is for one hundred years educate children.
Confucius
 
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  • #112
Cataclysmo
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"Tilted higher" is a bit of an arbitrary statement. The Moon's orbit is tilted at 5 degrees to the ecliptic (the Earth solar orbit plane). The Moon's orbit also has a nodal precession; It "wobbles". The period of this precession is 18.6 years. This, in turn means that the Lunar orbit varies from being 18.5 to 28.5 degrees in tilt with respect to the celestial equator over that 18.6 year period.

While in one year, at the winter solstice, the Lunar orbit will align so that the full moon can appear higher in the Southern sky (as seen from the Northern hemisphere) than the Sun does on the Summer solstice(The difference between maximum and minimum declination will be the greatest), 9.3 years later, the full moon will never get as high in the sky as the Sun does on the Summer solstice (the difference between declinations will be the least).
The Elegance of this description will make teaching others more efficient thank you.
 
  • #113
DaveC426913
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I have always imagined that the Sun revolves around the galaxy in a counterclockwise direction assuming the convention of looking down on it from "North" (i.e. moving to the right in typical pictures).

I never made the connection to the fact that the spiral arms spin out clockwise (as seen from the North/top).

You learn something new every day.
 
  • #114
Dr Wu
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Oh, for a 3D video representation of the entire shebang. . . and (in my case) the 3D means to view it :woot:
 
  • #115
sophiecentaur
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I never made the connection to the fact that the spiral arms spin out clockwise (as seen from the North/top).
It's worth while pointing out that the arms are not spinning like a Catherine Wheel Firework. They are just a density pattern or wave due to the interaction of each star with its 'close' neighbours. Density waves do not consist of the same stars all the time and do not travel at the same speed as their constituent stars so they can be looked upon as 'virtual'. Wiki gives a fair description of the effect.
 
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  • #117
diogenesNY
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That is neato-keen! Almost obvious (particularly the _winding effect_) if you stop to think about it, which I confess I have not until I read the wiki article.

diogenesNY
 
  • #118
Keith_McClary
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This is Venus, high in the morning sky, amid the faint pillar of light called the Zodiacal Light. The glow is sunlight reflected off cometary dust in the inner solar system.
Above is the centre of the Galaxy area of Sagittarius. Alan Dyer
https://amazingsky.net/2014/04/06/venus-in-the-zodiacal-light/

Since the Zodiacal Light lies in the ecliptic plane, we can see from this image that the plane of the solar system intersects the galactic centre.

(PF doesn't want to insert the image today.)
 
  • #119
Daystar
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20191018_114101.jpg
 
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  • #120
Daystar
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This is my "map" of the solar system with the orbits to scale. I have included the orbits of eight planets plus that of Pluto and the parts of Eris' orbit that falls into the frame. I will add some labels and a wire coming out of the map to indicate the passage of the system around the centre of the Milky Way. I'll also post a shot of the inner planets orbits as they are rather small in this picture.
20191018_114821.jpg
 
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  • #121
pishtaco
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Thanks Janus - I knew the moon's orbit was inclined relative to Earth's equator, but I didn't know it was inclined TOWARD the ecliptic. Interesting! I've included your suggestion in my diagram, which also includes phyzguy's suggestion. Really appreciate the input, hope this diagram isn't getting too busy.

View attachment 107362
That is a great modification. I think these diagrams are great at explaining what can be very complex as all these planes are at different angles to each other and hard to present in a way that makes sense in a 3D way. Great work, I am going to share these with a budding astronomer in the family. Thank you.
 
  • #122
pliney the whiney
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Thanks Janus - I knew the moon's orbit was inclined relative to Earth's equator, but I didn't know it was inclined TOWARD the ecliptic. Interesting! I've included your suggestion in my diagram, which also includes phyzguy's suggestion. Really appreciate the input, hope this diagram isn't getting too busy.

View attachment 107362
Wow. Great work. I was trying to do this in my head and it made my head hurt.
 
  • #123
Daystar
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Going back to fizixfan's first post and diagram, there were some comments about the solstices and equinoxes. I think that in that first diagram the solstices should be where the equinox labels are and vice versa. By the way why is fizixfan's name now struck through? Has he left the group?
 
  • #124
berkeman
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By the way why is fizixfan's name now struck through? Has he left the group?
Let's just say that he went from bad to worse in his behavior at PF over the 4 years that he was here, and by the end it was obvious that he had to leave. You won't see most of the worst of his posts, since they were obviously deleted.
 

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