Today marks the 23rd anniversary of Earth Day
. Celebrate the globe with this SciFri sampler:
There's artistry to creating the world, according to Rob Simmon, art director of NASA Earth Observatory. NASA's collection of Earth-from-space imagery dates back to the Apollo 8 mission, when astronauts snapped a picture of Earth rising over the moon. In this video from February 2012, Simmon and NASA scientist Gene Feldman explain how the modern "Blue Marble" images are made and how they relate to scientific study of the Earth.
Doug Wilson, a geophysicist at the University of California, Santa Barbara, explains in this 2011 video what we'd encounter if we drilled 6,000 meters below the seafloor to earth's mantle. The crust is made up of three layers—lava flows, sheeted dikes, and gabbro—all formed from magma that seeped up from the mantle.
Cartoonist Neil Wagner shares a few Earth Day facts, and a celebratory cartoon, with SciFri here
Finally, learn why Earth Day is also significant
to SciFri's host, Ira Flatow.