How do you explain the CMB anisotropy diagram?

AI Thread Summary
The discussion focuses on the Cosmic Microwave Background (CMB) anisotropy diagram, specifically the significance of the multipole moment on the x-axis. Participants express surprise at the physical relevance of high-order multipole moments, such as those reaching 1000. There is a request for clarification on the concept of "opening angle," with values mentioned ranging from 20 to 22. The conversation highlights the complexity of interpreting CMB data and the need for further explanation on specific terms. Understanding these elements is crucial for grasping the implications of the CMB anisotropy in cosmology.
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http://map.gsfc.nasa.gov/media/070950/070950b.jpg
So the x-axis is multipole moment, which I remember from 2nd-quarter electromagnetism. Anyways, it surprises me that 1000-order multipole moments can even be physically significant.
 
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I got a professor to explain most of it to me. But I still don't get "opening angle". You supposedly can get a value with an "opening angle of 20". Or 21. Or 22.
 
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