Maps

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Key Concepts:

• Maps represent the spherical sky or Earth on a plane

Let's begin with a brief discussion of sky maps.  They are no different from the familiar more familiar world maps.  If we imagine that CMB experiments looked "down" instead of up we'd represent the topography of the surface of the Earth as:

The map looks blurry because we've degraded the map to the 7 degree resolution of the COBE satellite.