Look upward / Look up

By habit, He looked upward and saw Orion and the Big Dipper, Gemini and the Pole Star, in the twinkling autumn sky.

This sentence is taken from Notebook by Nicholas Sparks. I wonder is it the same meaning if I replace the word “upward” by “up” ?

When looking up the oxford dictionary, upward is an adj and used only before noun. Why the author can write “Look upward”. Is it grammatical ?

Thank you for your help

This means ‘he looked in an upward direction’. The noun (direction) is assumed.

You could use ‘up’.

Beeesneees,
“Throughout the northern hemisphere, both over land and sea, one can see Polaris in the night to know the direction north.”
Is this sentence OK?

It is very awkwardly phrased.
This is what I’d say:
Throughout the northern hemisphere, on land and sea, one can find North by looking for Polaris in the night sky.

Hi, Beeesneees

“He looked upward” is another way to say ‘he looked in an upward direction’. The noun (direction) is assumed and omitted.
Could you give me an advice that when or in which case we can write with an assumption in English. Is it considered a right way to do in writing, especially in formal writing like novel, speech ?

Thank you for your help . Beeesneees