Set your alarm clocks - football starts at 9am/EST 6am/PST this week! #DETvsATL
https://t.co/bKhHal0sl4
— FOX Sports NFL (@NFLonFOX) October 21, 2014
This game will be played in London, and since the game will be on TV so much earlier than the usual Sunday games, FOX wants to make sure that people know about it so they don't miss it.
The only problem is that, anybody who follows the direction from this tweet literally will turn the game on one hour too late. The game does not kick off at 9am EST, it kicks off at 9am EDT. What's the difference? 9am Eastern Standard Time is one hour later than 9am Eastern Daylight Time.
"Daylight" time refers to Daylight Saving Time, the official setting in place across most of North America from the second Sunday in March until the first Sunday in November. When we observe Daylight Saving Time, we move our clocks forward one hour, which means that the hour that would naturally be 9am becomes 10am. Thus, 9am EST is actually 10am EDT, and anyone tuning in at 9am EST is tuning in at 10am EDT and thus has missed the first hour of the game.
Being a computer guy, there's one more angle: Eastern Standard Time is defined as UTC-5, which means five hours earlier than GMT (or UTC, the two are synonymous). Eastern Daylight Time is UTC-4. For those of us who deal with applications and programs that are time zone aware, this difference matters.
You may think that this is just an academic exercise and that this mistake doesn't matter, but consider this: there are two states in the United States that do not observe Daylight Saving Time, Arizona and Hawaii. Arizona is in the Mountain Time Zone (UTC-7), which is two hours earlier than Eastern time. However, during the summer, when most of the country advances the clocks one hour, Arizona remains on Standard time, meaning that it is three earlier in Phoenix than it is in New York during that period.
I live in Utah, which is also on Mountain Time. Throughout the winter, clocks are the same in Salt Lake City as they are in Phoenix, but when we in Utah spring forward, from MST to MDT, Arizona remains on MST, putting Phoenix on the same time as Los Angeles. Los Angeles is in the Pacific Time Zone (UTC-8), which becomes PDT during the summer. PDT is UTC-7, which is identical to MST. It does matter whether or not you get it right.
