USAP Science Practice Exam

The speed in question is about orders of magnitude larger than everyday motion—astronomical objects moving around the center of the Milky Way travel at speeds that are tens to hundreds of kilometers per second. In common quick estimates used for teaching, these galactic orbital speeds are often rounded to a value around 100,000 mph when expressed in miles per hour. Among the given options, that rough magnitude is the best match to the statement, since the other numbers are either far too small or clearly not in the same rough range. For context, the more precise measurement of the Sun’s actual orbital speed is about 220 km/s, which is roughly 490,000 mph, illustrating that the true value sits in the 10^5–10^6 mph range. The question uses a simplified figure, so selecting the option describing about 100,000 mph aligns with that approachable estimate.