Meaning of HORIZON in English
BAD : The tiny light looked like a star in the horizon.
GOOD : The tiny light looked like a star on the horizon.
on the horizon (NOT in ): 'The sun was setting on the horizon.'
BAD : Further education enables you to broaden your horizon.
GOOD : Further education enables you to broaden your horizons.
your horizons (WITH - s ) = the range of things that you are involved or interested in: 'As a politician, his horizons extend no further than the next election.'
Longman Common Errors English vocabulary. Английский словарь распространенных ошибок Longman. 2012