Certainly! On October 21st in the world of astronomy, we celebrate a fascinating discovery that occurred in 2003. On this date, astronomers Mike Brown, Chad Trujillo, and David Rabinowitz discovered what would later be recognized as the dwarf planet Eris.

Eris, named after the Greek goddess of discord and strife, caused quite a stir in the astronomical community. Initially thought to be the "10th planet" of our solar system, Eris played a pivotal role in the great planet debate that ultimately led to the reclassification of Pluto.

This icy world, located in the scattered disc region beyond Neptune's orbit, is slightly more massive than Pluto but has a smaller volume due to its higher density. Eris takes a whopping 557 Earth years to complete one orbit around the Sun, and its highly elliptical orbit takes it as far as 97 astronomical units from our star.

One of the most intriguing features of Eris is its moon, Dysnomia, named after the daughter of Eris in Greek mythology. This little moon, discovered in 2005, is believed to be about 700 km in diameter and orbits Eris every 16 days.

The discovery of Eris sparked a celestial controversy that shook the very definition of what we consider a planet. It forced astronomers to reconsider the criteria for planetary status, leading to the creation of the "dwarf planet" category in 2006. This decision not only affected Eris but also demoted poor Pluto from its planetary status, causing an uproar among space enthusiasts and spawning countless "Save Pluto" campaigns.

So, on this day, we can raise a toast to Eris – the troublemaker of the solar system – whose discovery quite literally changed our cosmic perspective and reminded us that the universe is full of surprises, waiting to challenge our understanding of the cosmos. Who knew a chunk of ice and rock billions of miles away could cause so much drama here on Earth?