Ah, December 11th! A date that shines brightly in the astronomical calendar, much like the stars themselves. Let me take you back to December 11, 2017, when a momentous event occurred that had astronomers buzzing with excitement.

On this day, the International Astronomical Union (IAU) announced the discovery of 'Oumuamua, the first known interstellar object to pass through our solar system. This cigar-shaped visitor from beyond our cosmic neighborhood was first spotted on October 19, 2017, by the Pan-STARRS 1 telescope in Hawaii, but it wasn't until December 11th that its true nature was confirmed and announced to the world.

'Oumuamua, which means "scout" or "messenger" in Hawaiian, caused quite a stir in the scientific community. This mysterious object, roughly 400 meters long and only about 40 meters wide, was traveling at a blistering speed of 87.3 km/s (196,000 mph) relative to the Sun. It was so fast that it was clear it wasn't bound by the Sun's gravity - a telltale sign of its interstellar origin.

The announcement on December 11th sparked a flurry of observations and wild speculations. Some even suggested it could be an alien probe! (Spoiler alert: it probably isn't, but wouldn't that be something?)

As 'Oumuamua tumbled through space, it reflected sunlight in a way that suggested it was rotating once every 7.3 hours. This cosmic tumbleweed had scientists scrambling to gather as much data as possible before it sped out of reach of our most powerful telescopes.

The discovery of 'Oumuamua opened up a whole new field of astronomy - the study of interstellar objects passing through our solar system. It's like finding out your quiet neighborhood is actually on an intergalactic highway!

So, on this day in 2017, astronomers around the world raised their telescopes (and perhaps a glass or two) to toast the first confirmed interstellar visitor to our cosmic block party. Who knows what other cosmic wanderers might be out there, just waiting to be discovered on future December 11ths?