The Case of the Strange Astronomy Test

Question

Nogginson Rossouw, professor of Astronomy at his university, set an exam a few days ago. However, it seems that all of the students who have taken the exam, wrote strange answers. The professor asked them to write short notes on 8 astronomy related topics and all of them have given weird answers. For example, one of the students, Drew Plater's answer script looks like this-

1. A measuring instrument and unit.
2. Organic compound found in our body.
3. A flat surface.
4. A hybrid between a primate and a carnivore?
5. Wooden case used for storing goods.
6. Divide and analyse a sentence.
7. Cost for a trip to the sun?
8. Humorous radiance?

Assuming that the students didn't purposefully perform vandalism, What were the topics the good professor asked his students to write notes on and why have they produced such strange results?

Answer 1

The students have produced strange results because

the topics are all missing a letter.

Topic 1:

mete(o)r

Topic 2:

(a)steroid

Topic 3:

plane(t)

Topic 4:

ap(h)elion (From @Takeshi)

Topic 5:

crate(r)

Topic 6:

parse(c)

Topic 7:

solar f(l)are

Topic 8:

co(s)mic ray