Cosmic Microwave Background

https://www.8thwall.com/xiaohanwu/sky-effects

The Cosmic Microwave Background (CMB) is the afterglow of the Big Bang.  Depicted on the sky in this AR app, the orange and blue regions are the cold and hot spots of the CMB.  These temperature fluctuations are extremely small, having amplitudes of only 1 in 10,000.  To detect this faint signal of the CMB, our telescopes must carefully scan the sky.  This app shows the scanning pattern adopted by our ground-based CMB telescopes in Chile.  The dark circle shows the position of the beam, and the grey areas illustrates the regions that the beam has swept across.  The telescope model used here isn't a CMB telescope because we don't have one at hand, but is another radio telescope in Chile called ALMA (downloaded from https://skfb.ly/ooHL8).