This Massive Galactic Wall Challenges Our Understanding of the Universe!

What is the largest known structure in the observable universe?
What is the main gas responsible for global warming?
What is the name for a compound with the same molecular formula but different structural formula?
What is the name for a polygon with eight sides?
What is the name for a type of study in which the researcher manipulates one or more variables to determine their effect on another variable?
What is the name for the study of carbon-containing compounds?
What is the process by which we learn through consequences (rewards and punishments)?