* No fixed order: Planets don't have a specific order within a galaxy. Galaxies are vast and contain billions of stars, each with its own planetary system.
* Ongoing discovery: Astronomers are constantly discovering new planets, making it impossible to definitively say which planet is "first."
* No center: Galaxies are not organized in a way that would allow for a "first" planet. They are swirling collections of stars, gas, and dust.
So, there isn't a planet designated as the "first" in the Milky Way galaxy.
