From DeepSkyVideos.

Mike Merrifield and Seth Shostak discuss a bewildering discovery in NGC 2403… and an offer to its alien inhabitants — Patreon bonus: https://www.patreon.com/posts/129506586 — Full Shostak video: https://youtu.be/xy2mE07Pp8E

NGC 2403 is also known at Caldwell 7
Our video on Caldwell 1 – https://youtu.be/Et2Ij161PXE
Our video on Caldwell 2 – https://youtu.be/Or3Db6ENf84
Messier 33 – https://youtu.be/4shqOBkCki8

Seth Shostak: http://sethshostak.com
Seth Shostak’s thesis: https://core.ac.uk/download/pdf/11812191.pdf

Mike Merrifield is an emeritus professor from the University of Nottingham: https://about.me/michael.merrifield

Messier Objects playlist: http://bit.ly/MessierObjects

Back us on Patreon: https://www.patreon.com/deepskyvideos

Astronomy at The University of Nottingham: https://www.nottingham.ac.uk/astronomy/

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Video by Brady Haran and James Hennessy