How Many Galaxies Are There?

We've been trying to count the galaxies in the universe since the mid '90s, but our estimates change as our tools improve. So what does our current estimate really mean?

Hosted by: Reid Reimers
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Sources:

https://arxiv.org/pdf/1607.03909v2.pdf
https://www.nasa.gov/feature/goddard/2016/hubble-reveals-observable-universe-contains-10-times-more-galaxies-than-previously-thought
https://www.theatlantic.com/science/archive/2016/10/so-many-galaxies/504185/
https://phys.org/news/2017-01-universe-trillion-galaxies.html
https://gizmodo.com/we-were-very-wrong-about-the-number-of-galaxies-in-the-1787750693
https://www.spacetelescope.org/news/heic1620/ [includes PR videos]
https://www.scientificamerican.com/article/universe-has-10-times-more-galaxies-than-researchers-thought/
https://www.nature.com/news/hubble-telescope-reveals-deepest-view-of-the-universe-yet-1.14489
https://www.nature.com/news/universe-has-ten-times-more-galaxies-than-researchers-thought-1.20809
http://www.skyandtelescope.com/astronomy-news/universe-2-trillion-galaxies/
https://www.smithsonianmag.com/smart-news/there-are-10-times-many-galaxies-previously-thought-180960796/
http://www.slate.com/blogs/bad_astronomy/2016/10/14/there_are_two_trillion_galaxies_in_the_universe.html

http://hubblesite.org/image/385/news_release/1996-01

Images:

https://www.spacetelescope.org/images/heic0814a/
https://www.spacetelescope.org/images/opo1724a/
https://commons.wikimedia.org/wiki/File:HubbleDeepField.800px.jpg
https://commons.wikimedia.org/wiki/File:Hubble_ultra_deep_field_high_rez_edit1.jpg
https://en.wikipedia.org/wiki/File:James_Webb_Space_Telescope_2009_top.jpg
https://www.spacetelescope.org/images/heic0910i/
https://www.spacetelescope.org/images/heic1215b/
https://www.spacetelescope.org/images/heic1414a/
https://www.spacetelescope.org/images/heic0911b/
https://www.nasa.gov/mission_pages/hubble/science/hst_img_20080520.html

Видео How Many Galaxies Are There? канала SciShow Space