tolkiens legendarium - Why was Bilbo not discovered by Sauron during his extended stay with the Wood Elves?

Currently reading The Hobbit to my daughter, and we came to the Barrels out of Bond chapter where the Dwarves are captured and imprisoned by the Wood Elves. Bilbo sneaks in with his magic ring of invisibility and eventually sets them all free.

But here's what piqued my curiosity: in the chapter it makes clear that Bilbo wore the one ring constantly for a very extended period of time: it specifically states he was down there at least two weeks and then - it's much less clear - possibly for even longer while he came up with and implemented his plan to rescue the Dwarves.

However in The Lord of the Rings, Frodo is constantly terrified of putting on the ring lest he (and the ring) should be located by Sauron. So why does Bilbo, wearing the ring for several weeks, escape detection?

The obvious thought is that Sauron was simply not powerful enough at this time. But that seems a pretty thin claim in many ways. Sauron was powerful enough to be "recognised" as a dangerous sorcerer in his guise as the Necromancer, and to start to gather his followers together. You'd have thought that simply locating the Ring would require a pitiful amount of comparative effort.

Furthermore I believe it's implied in The Lord of the Rings that it becomes increasingly dangerous to use the Ring the closer it gets to its maker (I don't have a reference for this - might be my imagination). If so, things become even more inexplicable since Thranduil's palace wasn't actually all that far from Dol Guldur, where Sauron was holed up.

Any explanation? Or do we have to chalk it up to the poetic license due to a world in development?

Answer

Because putting on the Ring doesn't cause you to be detected by Sauron.

However in The Lord of the Rings, Frodo is constantly terrified of putting on the ring lest he (and the ring) should be located by Sauron.

This isn't the case at all. Frodo only wears the Ring a total of 6 times in LotR - at Bombadil's house, in the Prancing Pony, on Weathertop, twice at the Breaking of the Fellowship, and on Mount Doom - and the only times Sauron is aware of him are the first time at the Breaking (where Frodo actually went looking first) and on Mount Doom (where Frodo claims the Ring for his own in the heart of Sauron's realm).

The times Frodo is afraid to put on the Ring are when he's being tracked by the Ringwraiths, and is under temptation to wear it so that they can have power over him in the shadow-world (because they have no power in the physical world). It's nothing to do with fear of detection by Sauron.

It's actually quite safe to wear the Ring otherwise.

Aside from what it will do to you of course, but otherwise the worst that can happen is that you'll turn into a Gollum over time, then finally become a wraith yourself.

Remember: Gollum had it for hundreds of years and was never detected.

Also consider Sam.

Sam actually wore the Ring in Mordor itself.

Without any clear purpose he drew out the Ring and put it on again ... He ran forward to the climbing path, and over it. At once the road turned left and plunged steeply down. Sam had crossed into Mordor. He took off the Ring ...

(RotK Book VI Chapter 1: The Tower of Cirith Ungol)

But yet Sam wasn't detected by Sauron either, so it's quite clear that putting on the Ring, even in Mordor, is safe enough to do.

It seems to me that the whole notion of "putting on the Ring causes Sauron to detect you" is a movie construct, because that's where it does happen, but you need to forget about that and focus on what happens in the books, and only what happens in the books.