How many letters does the top answer for “the line at which the sky and earth appear to meet” have?

The most common answer is horizon (7 letters).

Crossword clue: the line at which the sky and earth appear to meet

2 answers found in Letterora's clue database (Wikidata facts, Open Trivia DB, WordNet and Webster definitions — all licensed sources).

horizon 7 letters wn-def

the line at which the sky and Earth appear to meet

skyline 7 letters wn-def

the line at which the sky and Earth appear to meet