› added 7 years ago

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Have you ever played with a pocket-sized laser, wondering how far its light would travel? Could you, a naughty student inside a classroom on Earth, annoy a poor substitute teacher on Mars by waggling your laser pointer at him?

T​he short answer: no. By the time the light finally reached Mars, the glint would be a million times dimmer than the faintest light visible to the human eye.

Oovr1 TIL that the saying "O'Clock" is short form for "Of The Clock." It originated as early as the 14th century and was said to distinguish between other time telling methods.
QJEAd TIL that in 1994 a Boy Scout attempted to make a neutron gun and irradiated himself and his neighborhood in the process until he got arrested.
LkWPr TIL that Saturns’ rings are, cosmically speaking, a very brief event. We are about halfway through their 200 million year lifespan and are very lucky as a species to be alive to witness them. “Some velociraptor with a telescope looking at Saturn would not have seen rings.”
yVrp8 TIL about fire classes (in the USA) which each have specific ways to extinguish them—A (ordinary combustibles), B (flammable liquids/gases), C(electrical fires), D (metals like elemental sodium in water), and K (lipids/fats like kitchen fires).
awonN TIL Since its founding in the 1960s, the brand Vans has become a staple of American footwear culture, on the level with iconic brands like Converse (which is twice as old) and Nike (which is nearly 10 times as large)