By Mass:
* The current champion is likely the hypergiant "Stephenson 2-18"**. It's estimated to be around 250 times more massive than the sun, and potentially even larger, though its exact size is debated.
* However, there are likely other, even more massive stars lurking in the Milky Way that we haven't discovered yet. They are often hidden by dust and gas, making them very hard to observe.
By Size:
* If we're talking about the star with the largest radius, that title goes to "UY Scuti." It's a red supergiant estimated to be around 1,700 times the radius of our sun.
* Betelgeuse, another well-known red supergiant, also competes for the "biggest" title. Its size fluctuates considerably, and at times it may be even larger than UY Scuti.
Important Note: It's worth remembering that these are all very large and unstable stars. They are likely nearing the end of their lives and will eventually explode in spectacular supernova events.
So, there's no definitive answer to your question. The "biggest" star in the Milky Way is a constantly evolving title, and we're likely still discovering new stars that could challenge the current champions!
