The Milky Way galaxy moves within the Local Group, which is gravitationally bound and orbits a common center. Unlike the circular motion of the sun around the Milky Way's center, the dynamics of galaxies in the Local Group are more complex due to their larger sizes and interactions. These interactions can lead to phenomena such as galaxies ripping each other apart, indicating that their motion isn't simply elliptical. The mass distribution within the Local Group complicates the understanding of galaxy movements, suggesting they may not follow traditional orbital patterns. Overall, the Milky Way's movement is influenced by its gravitational relationships with other galaxies in the Local Group.
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abdossamad2003
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How does the Milky Way galaxy move in the local Group? Is there a circular motion around the center of the local Group like the sun moves around the center of the galaxy?
I believe the Local Group is gravitationally bound, so there is a common center about which its mass must collectively orbit. However, the group is only about 100 times the diameter of the Milky Way, so galaxies are much larger in comparison to the spaces between them than stars are, so they interact in more complex ways than stars typically do - ripping each other apart, for example.
All that means that I think you have a mass distribution that isn't really well described as a fluid (like a galaxy) or a collection of point masses orbiting one (like a solar system). So I would suspect that galaxy motions aren't pure ellipses, because they interact a lot (and there are definitely satellite galaxies of the Milky Way). But I am not certain.
Partial solar eclipse from Twizel, South Isl., New Zealand ...
almost missed it due to cloud, didnt see max at 0710 NZST as it went back into cloud.
20250922, 0701NZST
Canon 6D II 70-200mm @200mm,
F4, 100th sec, 1600ISO
Makeshift solar filter made out of solar eclipse sunglasses
3I/ATLAS, also known as C/2025 N1 (ATLAS) and formerly designated as A11pl3Z, is an iinterstellar comet. It was discovered by the Asteroid Terrestrial-impact Last Alert System (ATLAS) station at Río Hurtado, Chile on 1 July 2025.
Note: it was mentioned (as A11pl3Z) by DaveE in a new member's introductory thread.
https://www.physicsforums.com/threads/brian-cox-lead-me-here.1081670/post-7274146
https://earthsky.org/space/new-interstellar-object-candidate-heading-toward-the-sun-a11pl3z/
One...
are in a beautiful arrangement tonight as I have just observed on the walk back from the pub.
Does anyone have access to an image without city light pollution and better exposure control than my phone?
Edit: snapshot attached