18 February in history.

1930

Pluto is found. Clyde Tombaugh, a 24-year-old assistant at Lowell Observatory, spotted a faint moving dot while comparing photographs of the sky. It was Pluto.

Wikipedia: Clyde Tombaugh

Photo: NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute/A… / Wikimedia Commons (Public domain)

More from 18 February

1. 

   1885

   Huckleberry Finn reaches American readers

   Mark Twain's novel about a boy and an escaped enslaved man rafting down the Mississippi was published in the United States.

   Wikipedia: Adventures of Huckleberry FinnWikipedia: Mark Twain

   Photo: E. W. Kemble / Wikimedia Commons (Public domain)

2. 

   1911

   The first official airmail

   French pilot Henri Pequet flew about 6,500 letters a short distance across the river in Allahabad, India, on the first official airmail flight.

   Wikipedia: AirmailWikipedia: Henri Pequet

   Photo: Kristoferb at English Wikipedia / Wikimedia Commons (CC BY-SA 3.0)

3. 

   1930

   A cow takes to the skies

   Elm Farm Ollie became the first cow to fly in an airplane, and was milked during the flight over Missouri.

   Wikipedia: Elm Farm Ollie

   Photo: Man vyi / Wikimedia Commons (Public domain)

4. 

   1977

   The Space Shuttle rides a jumbo jet

   NASA's first shuttle, Enterprise, made its first flight carried on the back of a Boeing 747, the start of tests for a new kind of spaceship.

   Wikipedia: Space Shuttle Enterprise

   Photo: NASA / Wikimedia Commons (Public domain)

Moments chosen for discovery, creativity and courage. Each one links to a source where you can read more; photos are credited to their owners.