What is the main visual difference between the lunar highlands and the lunar maria? What are the implications of this observation?
What will be an ideal response?
Question 2
What is a planetary nebula?
A) The bipolar jets ejected by a T Tauri variable
B) A planet surrounded by a glowing shell of gas
C) The disc of gas and dust surrounding a young star that will soon form a solar system
D) The ejected envelope, often bipolar, of a red giant surrounding a stellar core remnant
E) A type of young, medium mass star