"An American Tail" (note spelling) was NOT a Disney production. It was produced by Amblin Entertainment and Universal Pictures. Steven Spielberg was executive producer (whatever that means). In the soundtrack, SOMEWHERE OUT THERE was performed by Linda Ronstadt and James Ingram. It won a Grammy for "Best Song Written Specifically for a Motion Picture or for Television" – so that rules out its being older than 1986. Since then, lots of other people have recorded it. Lyrics are available at lots of places on the Internet.

SOMEWHERE OUT THERE
James Horner, Barry Mann, Cynthia Weil

Somewhere out there, beneath the pale moonlight,
Someone's thinking of me, and loving me tonight.
Somewhere out there, someone's saying a prayer
That we'll find one another, in that big somewhere out there.

And even though I know how very far apart we are,
It helps to think we might be wishing on the same bright star;
And when the night wind starts to sing a lonesome lullaby,
It helps to think we're sleeping underneath the same big sky.

Somewhere out there, if love can see us through,
Then we'll be together, in that big somewhere out there.