Is There Life on Earth?

I mean… how do you really know?
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If we lived light years from Earth, how would we know there’s life here? Let’s take a look at the search for extraterrestrial life on habitable exoplanets, and discover what biosignatures would show someone else that we’re here.


Kaltenegger, Lisa. “How to Characterize Habitable Worlds and Signs of Life.” Annual Review of Astronomy and Astrophysics 55, no. 1 (August 18, 2017): 433–85.….

Sagan, Carl. “Is There Life On Earth?” Engineering and Science 35, no. 4 (1972): 16–19.

Sagan, Carl, W. Reid Thompson, Robert Carlson, Donald Gurnett, and Charles Hord. “A Search for Life on Earth from the Galileo Spacecraft.” Nature 365 (October 21, 1993): 715.

Schwieterman, Edward W., Nancy Y. Kiang, Mary N. Parenteau, Chester E. Harman, Shiladitya DasSarma, Theresa M. Fisher, Giada N. Arney, et al. “Exoplanet Biosignatures: A Review of Remotely Detectable Signs of Life.” Astrobiology 18, no. 6 (June 2018): 663–708.

Seager, Sara, and Drake Deming. “Exoplanet Atmospheres.” Annual Review of Astronomy and Astrophysics 48, no. 1 (August 2010): 631–72.….


Twitter: @DrJoeHanson @okaytobesmart
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It’s Okay To Be Smart is hosted by Joe Hanson, Ph.D.
Director: Joe Nicolosi
Writer: Joe Hanson
Creative Director: David Schulte
Editors/animators: Derek Borsheim and Sara Roma
Producers: Stephanie Noone and Amanda Fox

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