Point the binoculars or telescopes at the sun -- without looking through the lenses -- and aim the other end onto a piece of paper or cardboard.
As they describe in Nanoscale Research Letters, they have invented a way of concentrating the energy in the sun's rays without the need for mirrors.
Since San Juan is largely without power, when the sun goes down darkness prevails, pierced only by the occasional flicker of candlelight.
But a product's SPF indicates only its ability to defend against sunburn-causing ultraviolet-B rays and not against ultraviolet-A, which penetrate deeper into the skin and cause premature aging. (Both types contribute to skin cancer.) For example, a person wearing SPF 50 could spend considerable time in the sun without getting burned.
Without the earth's 23.5-degree tilt to the sun there would be no seasons, no variation in daylight and darkness, said Fothergill.
But those of you lucky enough to enjoy a more southern exposure should spend 15 minutes in the sun every day without sunscreen.
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City enjoyed more possession in the opening 90 minutes without causing the Doncaster defence too many alarms, save for a Sun Jihai shot in stoppage time which hit the bar.
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Instead, the prevalent Russian theory is that the Chinese will follow the advice of their great military philosopher Sun Tsu, who said the best general wins wars without fighting a single battle.
Would we really be calm and unconcerned if, just as suddenly, real light -- the sun's light -- without notice went away?
The sun has gone more than two years without a significant solar flare.
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For a sun-kissed stay along Banderas Bay, flock to the Flamingo without delay.
Without it, we might still fancy the Earth situated in the center of the cosmos, with the sun, the moon and all the stars orbiting around us.
Without expensive and difficult-to-maintain tracking systems, there is no way for flat panels to continuously face the sun.
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