This set of Astronautics Multiple Choice Questions & Answers (MCQs) focuses on “Flat Earth to Spherical Earth”.
1. One of the first to go against the Flat-Earth theory and obtain the circumference of the Earth was ___________
a) Isaac Newton
b) Edmund Halley
c) Albert Einstein
d) Eratosthenes
View Answer
Explanation: Eratosthenes was perhaps one of the greatest intellectual minds who ever lived and realized that the shape of our planet was not, as was widely believed, flat. He went on to be the first person ever to calculate the circumference of the Earth with mind-boggling accuracy (considering that there was virtually no scientific instrument available in 240 BC to aid humans) using just the concept of the angle of the shadows cast by two objects, each in two different locations whose distance away from each other was already known. He arrived at an estimate of 40,000 kilometers (fairly close to the present value of 40,075 kilometers).
2. The only way to identify the curvature of the Earth while stuck on the ground is to __________
a) observe a ship sail away from view
b) observe the ‘terminator’, i.e., the imaginary line that divides the moon’s illuminated and dark sides.
c) observe both a ship sailing away from view as well as the terminator
d)walk towards to the horizon
View Answer
Explanation: Observing a ship sailing away from view: If the Earth were truly a sphere (which it is), then the ship would gradually disappear from plain sight bottom-first (assuming perfect visibility conditions). Because of Earth’s curvature, the ship’s lowermost portion would first pass below the horizon (which exists only because of Earth’s curvature), and the remaining portion would then slowly vanish too, starting from the bottom and slowly making way up to the top. If the Earth were flat, then a ship would continue to be visible even after traversing an enormous distance, and at what instant it fades out of view is entirely dependent on eyesight and external visibility conditions.
Observing the terminator: The terminator is the boundary between the Moon’s sunlit and dark sides, and exists only because of Earth blocking some of the light coming from the Sun. This happens during the various phases of the Moon’s orbit around our planet. The terminator is always a curve, and this is only possible if the Earth were round (and not flat).
3. If the Earth were flat, then it would be difficult to account for _____________
a) the shadows cast by different spatially-separated objects
b) the day-and-night cycle
c) the seasons
d) its uneven surface
View Answer
Explanation: In a flat Earth, the shadows of various objects would cast the same angle on the surface irrespective of where they are located. The actual case, however, shows us that at different locations on Earth, the shadows are cast at different angles. The day-and-night cycle can be explained simply by making the assumption that the flat-Earth itself rotates about an imaginary pivot (say the geometric center of the surface).
4. Humans first experimentally witnessed Earth’s curvature using ______________
a) aircraft
b) satellites
c) high-altitude balloons
d) telescopes
View Answer
Explanation: In the early 19th century, scientists first looked at Earth’s curvature through pictures taken from high-altitude weather balloons from a height of around 22 kilometers above Earth’s surface.
Humanity first captured a photo of Earth from outer space about 70 years ago in 1946 using a German V-2 missile. The shot was obtained from an altitude of about 100 kilometers and clearly depicts the spherical shape of our planet.
5. Stars appear to rotate in circles in a westerly sense due to Earth’s counter-clockwise rotation. Stars located near the equator trace out bigger circles than those stationed near the poles (with a star right above the North or South Pole appearing to be fixed, not moving in any circle at all). In a flat-Earth theory, if we justify this observation by assuming that the flat-Earth itself rotates about its geometric center in the plane of the surface, then which of the following phenomena are, as a result, impossible to explain?
a) The day-and-night cycle
b) The seasons
c) The day-and-night cycle as well as the seasons
d) Long-term changes in the positions of distant stars
View Answer
Explanation: By assuming that the flat (say, rectangular or circular) Earth rotates in the plane of the surface itself, we can justify the apparent motion of the stars. The ones far away from the center of rotation trace out bigger circles than ones near the center of rotation. However, since we’re assuming an in-plane rotation, our flat world would maintain its pre-defined orientation with respect to the sun, experiencing long periods of eternal daylight and darkness depending on its position in orbit. An out-of-plane rotation is needed to explain both the motion of the stars as well as the 24-hour day-night cycle.
Sanfoundry Global Education & Learning Series – Astronautics.
To practice all areas of Astronautics, here is complete set of Multiple Choice Questions and Answers.
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