Answer:
Yellow fever is a disease caused by a virus that is spread through mosquito bites. Symptoms take 3–6 days to develop and include fever, chills, headache, backache, and muscle aches. About 15% of people who get yellow fever develop serious illness that can lead to bleeding, shock, organ failure, and sometimes death.
Explanation:
I copy and pasted this from the internet but you can easily summarize this in different words.
Assuming we're just looking at this phrase, "learn'd" suggests that the astronomer studied to become intelligent in the astronomical field.
