In mid-2025, astronomers confirmed the arrival of a remarkable cosmic visitor: 3I/ATLAS, the third known interstellar object to pass through our solar system. This object is an interstellar comet, meaning it originated around another star and is merely passing through our celestial neighborhood on a one-time journey. Prior to this, humanity had documented only two such interstellar interlopers – the enigmatic cigar-shaped 1I/‘Oumuamua in 2017 and the cometary 2I/Borisov in 2019. The discovery of 3I/ATLAS opened a new chapter in astronomy, giving scientists and the public a chance to study a piece of another star system up close. Comet 3I/ATLAS has captivated researchers worldwide. It was first detected by an automated sky survey and soon identified as an alien visitor not bound by the Sun’s gravity. Though faint and distant, this comet generated enormous excitement: for the first time in years, we had another messenger from beyond to observe. Over the ensuing months, telescopes across the globe (and even spacecraft in space) trained their eyes on 3I/ATLAS. What they found was a faint greenish comet on a hyperbolic path, racing through the inner solar system before heading back into interstellar darkness. The significance of 3I/ATLAS lies not just in its rarity, but in what it represents – a tangible link between our solar system and the wider galaxy. In the sections that follow, we will explore the story of 3I/ATLAS in depth, from its discovery and unusual orbit to its composition, comparisons with its interstellar predecessors, and the questions it raises about our place in the cosmos.