Aeronautics encompasses which of the following areas?

Aeronautics is the science and practice of designing, building, and flying aircraft. It encompasses various disciplines related to the study and implementation of flight technology both within the Earth's atmosphere and in space. Option C correctly highlights that aeronautics includes a combination of both aeronautics, which focuses on flight within the atmosphere, and aspects of space technology, which deals with flight outside the atmosphere.

The other options reflect narrower areas of study that, while related, do not encompass the full scope of aeronautics. For instance, focusing solely on atmospheric phenomena, as suggested in one of the choices, overlooks the significant element of space exploration in the wider field of aerospace. Earth and atmospheric sciences might include relevant elements, but do not specifically address the aviation technologies central to aeronautics. Furthermore, navigation techniques for pilots are indeed a part of aeronautics, but they are just one specific aspect and do not embody the entirety of the field or its intersection with space technology.