An adverb is a word that can describe or modify an adjective, verb, another adverb, or a sentence in its whole. Adverbs can be used to express manner, degree, place, and time (i.e., how something happens, to what extent, and when).
Here is the full paragraph after filling with adverbs
An astronomer used to wander eagerly at night to observe the stars. One evening, after dinner, he thought, "I want to look at some stars. I don't want to go too far. I'll go nearby." So he opened the door and walked briskly to an open field. As he walked, he kept looking intently upwards. His attention was fixed on the stars and so he accidentally fell into a well. He shouted for help. A farmer heard him and came .Learning what had happened the farmer Coldly look at the stars is all very well, but you must also be watchfully and see what is Currently on the earth! said, 'Sir, looking Tenaciously. look Earnestly