Rosa Parks sparks Civil Rights Movement. On this day in 1955, Rosa Parks, an African-American, was arrested and charged with violating a Montgomery, Ala., ordinance that required her to relinquish her bus seat to a white passenger. Her act of defiance sparked a yearlong bus boycott in the segregated city.
View full size image. The speed of light in a vacuum is 186,282 miles per second (299,792 kilometers per second), and in theory nothing can travel faster than light. In miles per hour, light speed is, well, a lot: about 670,616,629 mph. If you could travel at the speed of light, you could go around the Earth 7.5 times in one second.
In metric terms, the speed of light is a tad less than 300,000 km/sec. 1 light year is approximately 5.9 trillion miles, 20.5 light years would therefore be 20.5 times 5.9 trillion miles or about 120 trillion miles.