Uranus was not quite right. I had managed to return to the proper Italian sonnet rhyme scheme for the sestet, but there were still several faults. 

The first few lines talk about the view of Uranus from Titania always suspended on the horizon. But unless you know or think about tidal locking, you may wonder why it stayed there (other than by poetic license.) SO I made that explicit. In doing so, I fixed a minor issue with the scansion of the first line - having two adjacent three syllable words (horizon and Uranus) meant this line was not iambic pentameter like the rest of the poem. It is now.

The second problem was that the sestet did not really break into two sections, although the rhyme was correct. Instead, a sentence rambled across from line 3 to 4 in this passage. So that got a fair bit of a tweak, changing half of line 3 so the sentence ends on line 3 and a new concept starts on line 4.

All this resulted in about 5 full lines changed, as well as a couple changed for better grammar and scansion. And yet, the feel of the poem is almost identical. Those "not quite right" problems could probably have been tweaked with less work, but I'm much happier with what the extra effort has produced.

Uranus was discovered by William Herschel in 1781 with a homemade 6.2 inch reflecting telescope. In areas with extremely low light, it is visible to the naked eye (just) but had been mistaken for a star because it is so faint. Herschel discovered both Titania and Oberon, the largest and second largest of Uranus' moons, in 1787.

Both are tidally locked, presenting only one face to Uranus as happens with our own moon. So from Titania, Uranus will always be in the same place in the sky on the near side, its position in the sky dependent on your position on the moon. If you are close to the terminator line, the planet will appear low on the horizon. I've placed these astronauts so only half of Uranus is visible - the rest is hidden over the horizon.

From Uranus, the sun would have about 1/8th the diameter as seen from the earth, and be 390 times dimmer. It would be 2-3 times bigger than Venus as seen from earth, (and brighter because Venus only shines from reflected light.) So the "sun a distant star" is a slight exaggeration, but not far from the truth.