In astronomy, what is the scientific study of the Moon and its physical features called?

Introduction / Context:
Astronomy is a broad field that deals with celestial objects such as stars, planets, galaxies and natural satellites like the Moon. Within astronomy, various subfields focus on specific objects or phenomena. This question asks for the name of the scientific branch that deals specifically with the Moon, its surface, internal structure and related phenomena. Knowing such terms helps in understanding how science divides complex subjects into manageable disciplines.

Given Data / Assumptions:

- The topic is the scientific study of the Moon.
- Four terms are given: Selenology, Cosmology, Iridology and Planetology.
- We assume standard scientific terminology used in astronomy and related sciences.
- Only one term correctly refers to the study of the Moon.

Concept / Approach:
The term for the study of the Moon comes from Selene, a figure from ancient mythology associated with the Moon. Selenology is defined as the scientific study of the Moon, including its geology, surface features, composition and origin. Cosmology is the study of the origin and evolution of the universe as a whole. Iridology is associated with alternative medicine claims about the iris of the human eye. Planetology focuses on planets and planetary systems in general, not exclusively the Moon. By matching each term to its proper meaning, we can identify the correct answer.

Step-by-Step Solution:
Step 1: Recognise that the Moon is a natural satellite and has its own specialised field of study within astronomy.Step 2: Recall that Selenology, derived from Selene, refers specifically to the scientific study of the Moon.Step 3: Note that Cosmology deals with the universe as a whole, not just the Moon.Step 4: Understand that Iridology relates to the iris of the eye in alternative health claims.Step 5: Planetology focuses on planets and may include studies of many planetary bodies, so it is not limited to the Moon.

Verification / Alternative check:
If you recall word roots, you can verify the answer. The prefix selene is linked with the Moon. Words built from this root are typically associated with lunar science. In contrast, cosmo relates to the universe, and planet refers to wandering stars or planets. Remembering these roots helps you quickly decode scientific vocabulary in exam questions even if you have not memorised them separately.

Why Other Options Are Wrong:
Cosmology: This branch studies the large scale structure, origin and evolution of the universe and is not restricted to the Moon.
Iridology: This is a controversial alternative health practice that claims to diagnose conditions based on patterns in the iris of the eye and has no connection with astronomy.
Planetology: This field examines planets, moons and planetary systems as a whole, but the term for focused scientific study of the Moon is specifically selenology.

Common Pitfalls:
Some learners may choose cosmology or planetology simply because these terms sound more familiar from popular science. Others may be misled by similar sounding words without considering their roots. To avoid such errors, it is useful to learn a few common scientific prefixes and their meanings. Once you know that selen refers to the Moon, the term selenology becomes intuitive and easier to remember.

Final Answer:
The scientific study of the Moon is called Selenology.