How should I see the CMB picture

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    Cmb Picture
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Discussion Overview

The discussion revolves around the interpretation of the Cosmic Microwave Background (CMB) map produced by the Planck Telescope. Participants explore how to understand the representation of temperature variations across the sky as depicted in the CMB chart, specifically addressing the nature of its projection and spatial arrangement.

Discussion Character

  • Exploratory, Technical explanation, Conceptual clarification

Main Points Raised

  • One participant inquires whether the CMB chart can be viewed as a "planisphere," questioning the relationship between points on the chart and their spatial arrangement in a spherical context.
  • Another participant confirms that the CMB maps represent the surface of a sphere projected onto a 2D plane.
  • A third participant elaborates that the CMB is depicted using the Mollweide projection, noting its characteristics of area preservation but distortion of angles and shapes, particularly at the edges.

Areas of Agreement / Disagreement

Participants generally agree on the nature of the CMB map as a projection of a spherical surface, but there are nuances regarding the specifics of the projection method and its implications for interpretation.

Contextual Notes

There are unresolved aspects regarding the implications of the Mollweide projection on the interpretation of the CMB map, particularly concerning the distortions introduced at the edges.

Who May Find This Useful

This discussion may be useful for individuals interested in cosmology, astrophysics, and the interpretation of astronomical data visualizations.

the_pulp
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These days have been full of news of the Planck Telescope. The most popular is the actualization of the CMB picture (the ellipse with dots red and blue). I know the idea of it. Each dot represents the "temperature" in some direction (from the earth) in some sort of (θ;ψ) chart -0≤(θ;ψ)≤2[itex]\pi[/itex] . But how do I have to look at that chart? Is it some sort of "planisphere" where the north pole is just one point and the south pole is just another point. If that's it, if I go to the top right I appear in the top left -as in a planisphere", or not?

Just a silly yes or no question, but I couldn't find it in any place.
 
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The CMB is depicted using Mollweide projection, a pseudocylindrical representation of the sky. This method preserves the accuracy of areas, but, the angle and shape are distorted, especially at the edges. For further illustration see http://lambda.gsfc.nasa.gov/product/map/pub_papers/firstyear/basic/wmap_cb1_images.cfm. You may also find this of interest - http://arxiv.org/abs/1008.4085, Central symmetry and antisymmetry of the microwave background inhomogeneities on Wilkinson Microwave Anisotropy Probe maps.
 
Thank you both very much!
 

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