TODAY IN HISTORY

MARCH 13

 1852: Czar Alexander II of Russia is assassinated in St. Petersburg, by a bomb planted by members of the People's Will revolutionary group, which sought to overthrow the Russian monarchy. He is succeeded by his son, Alexander III.

1881:Frank Henry Bellew creates the first image of Uncle Sam, published in the New York Lantern newspaper on this day. Over the years, the image of Uncle Sam will come to embody the United States, portraying the nation as a kindly uncle.

1930: Clyde Tombaugh announces the discovery of Pluto, the ninth planet in our solar system, at the Lowell Observatory in Flagstaff, Ariz. Pluto is only one-tenth the size of Earth and, because it crosses the orbital path of neighboring Neptune, will be downgraded to "dwarf planet" status by the International Astronomical Union in August 2006.

Related articles

• The man who discovered Pluto is currently on his way there! (angelzero01.wordpress.com)
• Final push for Pluto's postage stamp - msnbc.com (blog) (cosmiclog.msnbc.msn.com)