Backtalk 2/19/2009

Feb. 17, 2009
The Earth is slowing down by about 0.002 sec/day, meaning that the Earth doesn’t rotate exactly once every 24 hr (or 86,400 sec)

Taking the Leap
The Earth is slowing down by about 0.002 sec/day, meaning that the Earth doesn’t rotate exactly once every 24 hr (or 86,400 sec). The Earth’s varying rotation is due to cumulative effects of friction from ocean’s tides, the Moon’s orbital momentum, snow (and the lack thereof) at the polar ice caps, the Earth’s 23°tilt, the atmosphere, solar wind, space dust ,and magnetic storms.

This slowing went unnoticed until atomic clocks arrived in the 1960s. Developed by the National Institute of Standards and Technology (NIST), the clock’s precise measurements of the Earth’s position relative to the stars indicated miniscule slowing of the rotation.

Prior to the atomic clock’s arrival, the definition of a second would be changed to match the Earth’s rotation. This changed in 1972 when it was decided by international agreement that the world’s atomic-clock operators would adjust the time of day by adding 1 sec — a leap second — to the world’s official time when needed to keep Coordinated Universal Time (UTC) in sync with astronomical time — the position of the sun above the Earth. When the International Earth Rotation Service observes that the Earth is out of sync with UTC, a leap second is scheduled. After several months notice, the leap second is added at 18:59.59 Eastern Time (corresponding to 23:59.59 at the zero median in Greenwich, England) on either Dec. 31 or June 30. If you’re interested in watching the leap second occur this year, log onto before midnight, London time, and clicking on their time zone.

The US Airways flight that ended in the Hudson River recently became an instantly popular, free online video game, “Hero on the Hudson.” (At press time, the hosting site, TastyPlay. com, indicates the originating site,, has been disabled.)

The scenario presented to players was: “Both engines are out. The plane is too low and too slow to make it to the airport. You decide to make emergency landing in the river.”

While flight dynamics are not presented in a flight-simulatorlike manner, players control the game via left and right arrows. Successful ditchings are signaled by passengers stepping out on the wings and a banner that declares you a hero. Players who fail to land the jet successfully watch it sink.

LEDs light up the Avenue of the Arts
With the flip of a switch, color-changing LED lights transformed Philadelphia’s Avenue of the Arts into a multicolor canvas this past holiday season. The lighting, from Philips Color Kinetics, Burlington, Mass., illuminated the historic facades to a synchronized score of The Nutcracker. The color-changing light show danced along buildings at the intersection of Broad and Walnut St., and in between the sound and light shows, coordinated lighting changes moved up and down the buildings. The dazzling display, permanently installed to illuminate nine buildings along the Avenue of the Arts throughout the year, uses Philips ColorGraze Powercore and ColorBlast Powercore fixtures.

Philadelphia’s 548-ft-tall City Hall was illuminated (just for the holidays) using Philips’ newest fixture, ColorReach Powercore, a high-performance architectural floodlight that illuminates large-scale buildings while curbing energy use and reducing maintenance. With more than 5,000 lumens of output and over 500 ft of light projection, the fixture consumes just 290 W, compared to its metal-halide counterparts that typically consume 1,600 W and require the use of filters to produce color.

The permanent lighting displays were designed by Philadelphiabased The Lighting Practice, and the architectural firm Vitetta. The installation was carried out by Philadelphia’s Gordon Electric with system- integration support by entertainment-solutions provider PRG.

Men ride shotgun on first dates
A recent poll of 500 women by shows that 18% now choose to drive on a first date (up 12% from last year). While LeaseTrader isn’t sure of the reasons; it could be that woman are taking a more-active role in selecting their vehicle or they’re in love with their vehicle (and not so sure yet about that date). According to LeaseTrader, “times are a changin’ and it’s time for men to ride shotgun on the first date.”

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