How big is the Universe? (Intermediate)

I am preparing a presentation to 16 year old students about "How big is the Universe", mainly about how it is measured. I wondered if you know what is the current record holder for the most distant object from Earth. If you could point me at a URL with pictures I would be grateful.

You might say that the most distant object visible from Earth is the Cosmic Microwave Background (CMB), the remaining heat from the early Universe which is visible all around us. The CMB radiation that is reaching us today traveled to us from a part of the Universe that is now over 45 billion light years away. It appears as a smooth, even distribution of thermal radiation with a temperature of about 3 degrees Kelvin, that we see coming from all directions. NASA and ESA have used 3 satellites to observed the CMB, COBE, WMAP and Planck, click on the names for more info on how the CMB is observed.

If you're picky about what you call an "object," the CMB may not qualify. The most distant objects observed are generally galaxies that are undergoing periods of rapid star formation, and are gravitationally lensed by a foreground object, making them even brighter and thus easier to detect. Although the most distance known object changes quite frequently, at the moment the most distant known object is a galaxy called EGSY8p7 (great name, I know). It has a redshift of 8.68, which corresponds to a distance of about 30 billion light years.

This page was last updated on November 9, 2015.

About the Author

Mike Jones

Mike is a fourth year astronomy graduate student at Cornell, where he works with Professors Martha Haynes and Riccardo Giovanelli on the ALFALFA survey, a blind survey of gas-rich galaxies in the local Universe carried out with the 305m Arecibo telescope in Puerto Rico.


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