Our galaxy, the Milky Way, has a diameter of about 100,000 light years. How many years would it take a spacecraft to cross the galaxy if it could travel at 99% the speed of light? A) 1.4 × 10³ yrs B) 1.0 × 10⁵yrs C) 1.4 × 10⁴ yrs D) 7.2 × 10³ yrs E) None of these is correct.

Question

Quizplus · Accepted Answer

The distance across the Milky Way is approximately 100,000 light years. If a spacecraft could travel at 99% of the speed of light, then we can use the formula:
Time = Distance/Speed
Time = 100,000 light years / (0.99c)
Time = (100,000 light years) / (0.99 x 299,792,458 m/s)
Time = 1.39 x 10^14 years or 1.4 x 10^14 years (rounded to two significant figures)
Therefore, the answer is option C: 1.4 × 10^14 years.

Our Galaxy, the Milky Way, Has a Diameter of About