Learn Hardcore Russian: Мне всегда было интересно смотреть на звёзды через телескоп. - I have always been interested in looking at the stars through a telescope.

Why does the sentence use Мне instead of Я? In English we say I have always found it interesting…, but in Russian it’s Мне всегда было интересно…

Russian often uses the dative case to express the experiencer of a feeling or state. So:

Мне всегда было интересно… = literally: To me it was always interesting…
The form мне is dative of я.

This is the same pattern as:

Мне холодно. – I am cold. (literally: To me it is cold.)
Ему скучно. – He is bored. (literally: To him it is boring.)
Мне трудно говорить по‑русски. – It’s hard for me to speak Russian.

So instead of saying Я интересуюсь смотреть на звёзды, Russian treats интересно as a kind of impersonal description, and the person who experiences it is in the dative: мне.

What is the grammatical subject here? Why is it было in neuter, not был or была?

The sentence is impersonal: it doesn’t have a grammatical subject like я, он, это, etc.

было is the neuter singular past tense form of быть used in impersonal constructions.
интересно is a short-form adjective used like a predicate: (было) интересно = it was interesting.

So the structure is basically:

(Мне) + (было) + интересно + (что делать?) смотреть на звёзды…

There is no noun or pronoun in nominative acting as subject. In such impersonal sentences, Russian uses neuter singular for the past-tense verb.

Why is it всегда было интересно (past tense) if in English we say has always been interesting (a kind of present-perfect idea)?

Russian does not have a present perfect tense like English. To express “has always been,” Russian usually uses:

Past tense + всегда
Мне всегда было интересно… = I have always found it interesting…

This form:

can cover your whole life up to now, not only a finished past;
doesn’t necessarily say whether it is still true now, but context usually implies it still is.

If you strongly want to emphasize it is still true now, you could say:

Мне всегда было интересно смотреть на звёзды через телескоп, и до сих пор интересно. – I have always found it interesting to look at the stars through a telescope, and I still do.

Or just use present:

Мне всегда интересно смотреть на звёзды через телескоп. – It is always interesting for me to look at the stars through a telescope.

Can we change the word order, like Мне интересно было всегда смотреть на звёзды…? How flexible is the word order here?

Russian word order is flexible, but not all variants sound equally natural. Some possibilities:

Мне всегда было интересно смотреть на звёзды через телескоп.
– Neutral, natural, what you were given.
Мне было всегда интересно смотреть на звёзды через телескоп.
– Also possible, but всегда sounds a bit more highlighted.
Всегда мне было интересно смотреть на звёзды через телескоп.
– Emphasizes always (as contrast: it was *always interesting to me*).
Мне интересно было всегда смотреть на звёзды через телескоп.
– Grammatically possible, but sounds awkward and unnatural for most contexts.

In normal speech/writing, the original word order (Мне всегда было интересно…) is the best and most idiomatic.

Why is смотреть in the infinitive? Could it be когда я смотрю or something like that?

After adjectives like интересно, трудно, легко, Russian very often uses an infinitive to express “doing something”:

Мне интересно смотреть на звёзды. – It is interesting for me to look at the stars.
Ему трудно работать ночью. – It is hard for him to work at night.

So смотреть here answers что делать? – what (to) do?

If you change it to a finite verb like когда я смотрю, you change the structure and the meaning:

Мне всегда было интересно, когда я смотрю на звёзды через телескоп.
This sounds odd and incomplete; you would expect something after it (e.g. что‑то происходит).

The natural pattern is:
Мне (кому?) + было интересно (как?) + смотреть (что делать?) на звёзды…

Why is it смотреть на звёзды, with на, instead of just смотреть звёзды?

With the meaning to look at / to watch, the verb смотреть normally takes на + accusative:

смотреть на звёзды – to look at the stars
смотреть на картину – to look at a painting
смотреть на людей – to watch people

Without на, смотреть usually means more like to watch (a show/film/program):

смотреть фильм / телевизор / спектакль – to watch a film / TV / a play

So:

смотреть на звёзды – correct and idiomatic (you’re directing your gaze at them).
смотреть звёзды – sounds wrong or at least very unnatural in this meaning.

What case is звёзды in, and why does it look like nominative plural but is used with на?

звёзды is feminine plural accusative of звезда.

For feminine nouns ending in ‑а / ‑я, the nominative plural and accusative plural forms are often identical:

Nominative plural: звёзды есть на небе.
Accusative plural: смотреть на звёзды.

The preposition на with a verb like смотреть на requires the accusative. So grammatically it is accusative, even though the form looks like nominative.

Why is it через телескоп? Could we also say в телескоп? What is the difference?

Both are possible, but they emphasize different things:

смотреть через телескоп
– literally: to look through a telescope
– focuses on the medium through which you see the stars (the optical path).
смотреть в телескоп
– literally: to look into a telescope
– focuses a bit more on looking into the device itself.

In practice, when speaking about astronomy, both can be used and will be understood as looking at stars using a telescope. Many speakers slightly prefer в телескоп in everyday speech, but через телескоп is also normal and clear.

Could we use a different verb, like наблюдать or глядеть, instead of смотреть? Would that change the meaning?

Yes, but with some changes in structure and nuance:

наблюдать
Usually takes за + instrumental when meaning “observe”:
- Мне всегда было интересно наблюдать за звёздами в телескоп.
  – I have always found it interesting to observe the stars through a telescope.
наблюдать sounds a bit more scientific, like to observe rather than just to look.
глядеть
Colloquial, often used like смотреть:
- Мне всегда было интересно глядеть на звёзды через телескоп.
This is more informal; смотреть is more neutral and standard.

So смотреть на звёзды через телескоп is a good neutral choice.

Can we omit мне and say just Всегда было интересно смотреть на звёзды через телескоп?

Yes, you can omit мне, but the meaning shifts slightly:

Мне всегда было интересно… – clearly “I have always found it interesting…”
Всегда было интересно смотреть на звёзды… – more like “It has always been interesting to look at the stars…” (in general), without explicitly saying to whom.

In many contexts, listeners will still assume you’re talking about yourself, but grammatically, the version with мне is clearer and more personal.