As you know the old (4.5 billion years) sun is incredibly powerful. Actually without sun there would be no live plants, no energy, no life on Earth! So we are pretty dependent on that big (radius: 432,500 miles/ 696,000 km) thing up there.

But like everything, too much of anything can be bad for you. Which you may know way too well having experienced a sunburn. What is damaging for your skin in sunrays is the ultra violet radiation.

Scientists talk about 3 different types or lengths of ultra violet radiation. The shorter the more dangerous. The longest (UV-A) causes sunburn, the shorter (UV-B) can cause skin cancer and the shortest (UV-AA) can be used to sterilize stuff because it kills bacteria and viruses!

Of course ultraviolet radiation is good for something; a large portion of the vitamin D that humans and animals need for good health is produced when the human's or animal's skin is irradiated by ultraviolet rays.

The Ozone Layer
above the North Pole...

To see the latest
picture (daily) click here

But, again if all the ultraviolet radiation produced by the sun were allowed to reach the surface of the Earth, most life on Earth would probably be destroyed. Fortunately, the ozone layer of the atmosphere absorbs almost all of the short-wavelength ultraviolet radiation, and much of the long-wavelength ultraviolet radiation protecting all us down here.

The bad part is that in the 1980s, scientists began finding evidence that the ozone layer was being depleted. Or in other words holes were starting to form in the layer, especially over the North – and South Poles.

So what is ozone? Ozone is a naturally occurring gas that is found in two layers of the atmosphere. It is a pale blue, relatively unstable molecule. In Greek the word ozone means "to smell" and as the name suggests, it has a strong odor which you may have smelled during electrical storms or if some electrical device like your toaster got fried!

In the layer surrounding the Earth’s surface (the troposphere) ground-level or "bad" ozone is an air pollutant that is a major factor of urban smog.

The troposphere extends up to the stratosphere, which is where "good" ozone protects life on Earth by absorbing some of the sun’s UV rays. Stratospheric ozone is most concentrated between 6 to 30 miles above the Earth’s surface.

Though ozone is pretty tough it does have some enemies such as methyl bromide (used in pesticides), halons (used in fire extinguishers) and methyl chloroform (used in industrial processes). Unfortunately, as you can see of these few mentioned, we humans release a rather large amount of this into the air which then depletes the ozone layer that protects us against the damaging UV rays from the sun.

Realizing how damaging CFCs and other substances are to our planet, countries around the world have signed a treaty called the Montreal Protocol to phase out the production and use of ozone-depleting substances.

You can check out the UV Index daily -- It basically tells you how thin the ozone layer is that day ...and how much you should protect yourself!

Click here to see how it works.

So, now everything is ok, right!? Not quite yet. Unfortunately it will take probably ten more years before scientists can see the results of this treaty since the ozone depletion is such a slow process. The lucky part is that natural atmospheric processes eventually will repair the ozone layer. Probably around the middle of the 21st century. Until then, we can expect increased levels of UV radiation hitting the Earth’s surface. These increased UV levels can lead to a greater risk of overexposure to UV radiation and related health effects. Meaning you have to be very careful and protect yourself against the sun.

The danger of exposure to increased UV levels is actually what we here in the US consider a "serious public health threat" which is why the U.S. Environmental Protection Agency (EPA) is working with schools and communities across the nation through the SunWise School Program to make us all sun smarter. Check it out here !

Put on a Hat
Notice how your eyes, ears, face and back of the neck are hard to protect and always get red first!? A hat solves that problem.

Wear GOOD Sunglasses
They must block 99-100% of UV radiation...or they may do more damage than good! If you do not wear them it can lead to cataracts and other eye damage.

NOW, test your
UV, Sun and Ozone knowledge
at  the puzzle!