The correct spelling of the phrase "wert on the horizon" is with a 'w', not with a 'u'. The 'w' in 'wert' is pronounced like the 'w' in 'water' and the 'e' is pronounced like the 'e' in 'her'. The IPA phonetic transcription of the word is '/wərt/'. This phrase is often used metaphorically to represent a future event or situation that is approaching and can be seen coming from afar. Therefore, it is essential to spell the word correctly to convey the intended meaning.