REUTERS/NASA/Handout via Reuters/File Photo Earth's 28 fastest days ever recorded happened in 2020. On average, the planet rotated more quickly around its axis last year than it did in previous years. Scientists who measure the speed of Earth's rotation think 2021 may be even faster than 2020. If so, they may need to subtract a second from the year. As it turns out, 2020 was shorter than previous years – even though it didn't always feel that way. The 28 fastest days on record since 1960 all happened last year, since Earth revolved around its axis up to 1.5 milliseconds faster than usual. Those 28 days all broke the previous record for the shortest day ever documented: July 5, 2005. That day lasted 1.0516 milliseconds less than the standard 86,400 seconds. Now, the shortest day ever recorded lasted .45 milliseconds less than that previous record.