<p align="right">Last Update: <font color="#4f81bd">January 07, 2025</font></p> ## BIG IDEAS - Cosmic Microwave Background (CMB) Analysis helps scientists infer the geometry and size of the universe. - The redshift of light from distance galaxies is used to measure velocities relative to Earth. - By comparing the observed brightness of supernovae with their intrinsic brightness, astronomers can calculate their distances. --- ### Scale of the Universe The scale of the universe is monumentally difficult to picture. The latest estimates are that in the known universe there are over 2 trillion [[galaxies]]. ### Techniques > The technique makes use of a familiar property of any sort of wave motion, known as the [[Module 4 Doppler Effect|Doppler effect]]. $^1$ > The time between crests is just the [[Wavelength|wavelength]] divided by the speed of the wave, so a wave sent out by a source moving away from us will appear to have a longer wavelength than if the source were at rest. $^1$ ### Hubble's Law According to Hubble's Law, the farther away a galaxy is, the faster it appears to be receding from us, which indicates the universe's expansion. By measuring the redshift and using the known rate of expansion ([[Hubble constant]]), cosmologists can estimate the distance to faraway galaxies. ### Slide Deck <div style="position: relative; width: 100%; height: 0; padding-top: 56.2500%; padding-bottom: 0; box-shadow: 0 2px 8px 0 rgba(63,69,81,0.16); margin-top: 1.6em; margin-bottom: 0.9em; overflow: hidden; border-radius: 8px; will-change: transform;"> <iframe loading="lazy" style="position: absolute; width: 100%; height: 100%; top: 0; left: 0; border: none; padding: 0;margin: 0;" src="https://www.canva.com/design/DAGaEEY_sdM/cYjBv80z2nUB9TmywRvyww/view?embed" allowfullscreen="allowfullscreen" allow="fullscreen"> </iframe> </div> ### Related Topics --- [[Home|Home]] | [[The Universe]] | [[The Big Bang|The Big Bang Theory]] | [[Solar System]] | [[Galaxies]] | [[Star Clusters]] | [[Superclusters]] | [[Black Holes]] ### Footnote [1]: Weinberg, S. (1993). _The first three minutes: A modern view of the origin of the universe_. Basic Books. p. 15.