Events
1655 - Saturn's largest moon, Titan, is discovered by Christian Huygens.
1979 - The first fully functional space shuttle orbiter, Columbia, is delivered to the John F. Kennedy Space Center to be prepared for its first launch.
1992 - Cosmonaut Sergei Krikalev returns to Earth after a 10-month stay aboard the Mir space station.
Births
1539 - Christopher Clavius, German mathematician
1800 - Heinrich von Dechsen, German geologist
1863 - Simon Flexner, American pathologist
1884 - Georges Imbert, Alsatian chemist
1946 - Maurice Krafft, French vulcanologist
1952 - Antanas Mockus, Colombian mathematician
Deaths
1712 - Nehemiah Grew, English naturalist
1818 - Caspar Wessel, Danish mathematician
More like this
After spending all last weekend preparing our income tax return, I must have money on my mind. So this week's Casual Fridays study is about money. I don't want to tell you much more about it before you participate in the survey because it may affect the results, so just go ahead and click.
It's been a while since I've written a topology post. Rest assured - there's plenty more topology
Topology usually starts with the idea of a *metric space*. A metric space is a set of values with some concept of *distance*. We need to define that first, before we can get into anything really interesting.
Metric Spaces and Distance
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In the mid-1970s, the U.S. State Department prohibited the internal use of the term "space colony," due to the global bad reputation of colonialism.
You know, that photo bears quite some resemblance to your userpic. Which, by the way, is impressively emo. Good gad. What are those freshmen doing to you?