Astronomy Tonight for - 01-05-2025

On January 5th in astronomical history, one of the most significant events occurred in 2015 when astronomers announced the discovery of the oldest known solar system in our galaxy. This ancient system, named Kepler-444, is estimated to be about 11.2 billion years old, making it nearly 2.5 times older than our own solar system! Kepler-444 consists of a host star slightly smaller and cooler than our Sun, orbited by five small, rocky planets. These planets are all smaller than Earth, with the largest being about the size of Venus and the smallest about the size of Mercury. What's truly mind-boggling is that all five planets orbit their star in less than 10 days, with the closest planet whizzing around in just 3.6 days! Now, imagine being an astronaut on one of these planets. You'd need to pack sunscreen with an SPF of about a million, as you'd be much closer to your star than we are to the Sun. And forget about long, lazy years – you'd celebrate your birthday every few days! But here's the kicker: this system formed when the universe was only about 20% of its current age. That means if the universe were a person, Kepler-444 would have formed when it was still a teenager! This discovery challenged our understanding of planetary formation, suggesting that the universe was capable of creating rocky planets much earlier than we thought possible. So, as you look up at the night sky today, remember that among those twinkling stars could be ancient solar systems that have been around for most of the universe's existence. It's a humbling thought that makes our own 4.6-billion-year-old solar system seem like a cosmic newcomer!