I am very interested in astronomy.
as-tro-no-MI-a: stress on fourth syllable. 'Interessa' = in-te-RES-sa.
Use this for intellectual or scientific hobbies. It signals curiosity and an enquiring mind. Italians with similar interests will appreciate the specificity and may mention famous Italian astronomers like Galileo.
'Interessare' follows the piacere pattern: 'mi interessa' (it interests me) with the subject being the thing of interest. Plural subjects require 'mi interessano': 'mi interessano le scienze' (I am interested in sciences).
Sono affascinato/a dall'astronomia.
I am fascinated by astronomy.
'Affascinare' adds a sense of wonder and enchantment
Ho un telescopio e osservo le stelle.
I have a telescope and I observe the stars.
Describes the practical activity — very specific
Partecipo a un gruppo di astrofili.
I am part of an amateur astronomy group.
Shows community involvement in the hobby
Italy has a glorious astronomical heritage — Galileo Galilei was Italian, and the Vatican Observatory (Specola Vaticana) is one of the oldest astronomical institutions in the world. Many Italian towns have amateur astronomy clubs and dark-sky reserves for stargazing.