An optical double is an illusion—the stars are at vast distances from each other and are not actually orbiting each other—whereas in a visual binary, the stars are actually orbiting each other. its total energy output into all space
GOLD IN THE SKY - By Alan E. Nourse
We can see in the story that the setting is in a cockpit, in a lab, simulating a landing to Mars because of this paragraph; "Greg twisted around in the cockpit that had been built just big enough to hold him, and shifted his long legs against the brace-webbing, trying to get them comfortable." We can see that Greg Hunter is nervous, "His heart hammered in his throat, and his eyes ached fiercely, but he paid no attention. His finger crept to the air-speed indicator, then to the cut-off switch." The time period we can state is around the 1950s. It implied the first trip to Mars, "He heard the count-down monitor clicking in his ears, and his hands clenched into fists. How far from Mars would he be 10 minutes from now?" In conclusion, the time is believed to be sometime in the 1950s, and the setting is in a lab where Gregory Hunter is going on a trip to mars when something wrong has happened.
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Answer: Getting scholarships to further their education, motivates high school students to join professional organizations
Explanation: The reason is because a person is able to work legally when he/she turns 18 and there are many students in the United States, who want to get further education but cannot due to financial constraints. Thus, many students are motivated to join a professional organization to save money and get scholarships for their higher studies.