The Identification of "Spiral Nebulae" as Large Groupings of Stars

question 52

Multiple Choice

The identification of "spiral nebulae" as large groupings of stars outside of our own galaxy was proven by ____.

• A) photographic plates made by Edwin Hubble showing stars and Cepheid variables
• B) the results of the Shapley-Curtis debate
• C) Immanual Kant's "island universe" theory
• D) William Parsons' observation and description of their spiral structure
• E) Harlow Shapley's observations of their radio spectrum

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Definitions:

Monopolistically Competitive

Refers to a market structure where many firms sell similar, but not identical, products, allowing for some degree of market power and differentiation.

Profit-Maximizing Output

The level of production at which a firm achieves the highest possible profit, where marginal revenue equals marginal cost.

Short Run

A period in economic theory during which some factors of production are fixed, and only some variables, typically labor or raw materials, can be adjusted.

Average Total Cost

The total cost divided by the number of units produced, representing the cost per unit of output.