"He studies astronomy".
Astronomy is a long word.
My brother is studying astronomy.
When it is at the start of a sentence.
I want to study astronomy later on in life.
I like the study of Astronomy. Of course.
He always dreamed of astronomy as his future profession, but he became a doctor instead.
When I hammered the nail, I accidentally hit my thumb. The astronomy teacher hammered the basics of star formation into our heads over and over again.
You can use the word Truss in a sentence like this.
Can you use the word concluding in a sentence? Done.
No, it shouldn't all be uppercase, and it doesn't need to be capitalized unless it is the first word in a sentence or part of a title.
Just use it! Or do you mean, can you use the word beheld in a sentence.
I don't believe in astrology. Astrology and astronomy used to be the same science.