The Shell of a Planetary Nebula Is Measured by the Doppler

question 109

Multiple Choice

The shell of a planetary nebula is measured by the Doppler shift of emission lines to be expanding outward at a speed of 10⁴ m/s, while its radius is measured to be 1 ly, or about 10¹⁶ m. Roughly how long has the shell been expanding? (Hint: 1 year = 3.15 *10⁷ sec.)

• A) 30 years
• B) 30,000 years
• C) 30 million years
• D) 10¹² years

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Definitions:

Industrial Workers of the World

Radical union organized in Chicago in 1905 and nicknamed the Wobblies; its opposition to World War I led to its destruction by the federal government under the Espionage Act.

American Federation of Labor

An early 20th-century national federation of labor unions in the United States, focused on better wages, hours, and working conditions.

Conservative

A belief system advocating for the preservation of conventional social norms and structures.

Pure Food and Drug Act

A 1906 U.S. law aimed at regulating the production and sale of food and medicine, marking the beginning of federal consumer protection in the United States.