The sun delivers the most UV when it is high overhead at midday in the spring or summer. A good rule of thumb is: "if your shadow is shorter than you are, you must protect yourself from the sun."
My Mom noticed the sky looked like there were a trillion stars last night. So we looked into it!
While blue-white Deneb maybe the third brightest member of the Summer Triangle stellar formation and ranked as the 19th brightest star in our sky, don't be fooled by its apparent weakness. Marking the tail of Cygnus-the swan constellation (or head of the cross), this star is one of the most powerful and remote stars visible to the unaided-eye anywhere on Earth.
Located at least 1500 light years away, Deneb is still one of the brightest celestial beacons in our sky. Burning 70,000 times brighter than our sun, this supergiant is ranked as one of the brightest stars in the entire Milky Way galaxy. If Deneb was as close to Earth as Vega (25 light years) it would cast shadows at night and be visible even in daytime. But if it were as close as the wintertime powerhouse Sirius (8 light years), Deneb would shine brighter than the full moon. With over 25 times the mass of our Sun, astronomers estimate that in the next million years or so Deneb might blow itself up in a supernova explosion.
- Andrew Fazekas
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