Why Was It Difficult for Astronomers to Develop a Clear

question 45

Essay

Why was it difficult for astronomers to develop a clear understanding of the Milky Way until the last few decades?

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Definitions:

Oxygen-Rich Blood

Blood that is high in oxygen concentration, typically found in the arterial system after oxygenation in the lungs.

Liver

A large vital organ in vertebrates responsible for detoxification, protein synthesis, and production of biochemicals necessary for digestion.

Lymphocytes

A type of white blood cell that is one of the main types of immune cells, responsible for producing antibodies to fight off infections.

Lymph Node

Small mass of lymphoid tissue through which lymph filters; contains many B cells and T cells.