Posts Tagged ‘UV Rays’

The Sun and its UV rays

9 July, 2009

If you’ve not totally forgotten Science class, you’ll recall that sunlight is made up of the spectrum of light of many colours at different wavelengths.

(Richard of York Goes Battle In Vain, anyone?)

So, beyond the red part of the solar spectrum, you’ll find infrared radiation. And, at the other end of the spectrum, is ultraviolet (UV) light.

Image: NASAThere are basically three kinds of ultraviolet (UV) radiation that the Sun emits. UVA, UVB and UVC. UVA is long wave, also known as black light. UVB is medium wave and UVC is short wave, or germicidal.

UV rays are important because they assist our bodies in making vitamin D, which strengthens bones and teeth and helps our bodies build immunities to diseases, among other medical qualities.

Besides being also used in the treatment of some medical conditions, UV rays have various commercial uses as well, such as sterilisation and disinfection.

Some animals can see UV rays, and UV vision helps bees to collect pollen from flowers.

SunburnHowever, in spite of all their positive uses, UV rays remain very harmful for anyone who spends a large amount of time in the sun without proper protection. The most common effect of exposure to UV rays is sunburn.

Sunburn is the damage caused to skin cells when they have absorbed too much energy from UV rays.

What happens is that the UV rays penetrate the top layer of skin and burns the layer beneath that.

The sunburn causes blood to rush to the affected area as the body tries to cool the burn, which accounts for the “redness” immediately after a sunburn. The damaged skin ultimately peels away.

BUT, that’s not all.

Long term exposure to the Sun and its UV rays without proper protection increases one’s risk of skin cancer.

SunburnThe Earth’s ozone layer blocks out 98.7% of UV radiation from entering our atmosphere, protecting us from its harmful effects. (That’s why it’s important to stop global warming and not destroy the ozone layer.)

At least on July 22, the Moon will stop the Sun for a full 6 minutes and 39 seconds. If you get a chance to witness it, don’t miss it because this will be the longest total eclipse of this century.


Know the Sun to stop the Sun

3 July, 2009

I wonder if we will ever get to see the Sun like this.

Author: Hinode JAXA/NASA

This image of the Sun was taken by Hinode‘s Solar Optical Telescope on January 12, 2007 and reveals the filamentary nature of the plasma connecting regions of different magnetic polarity on the surface of the Sun.

Hinode (ひので, Japanese: “Sunrise”; English pronunciation: hee-no-day), formerly known as Solar-B, is a Japan Aerospace Exploration Agency Solar mission with USA and the United Kingdom. Hinode is on a planned three-year mission to explore the magnetic fields of the Sun. It consists of a coordinated set of optical, Extreme Ultraviolet (EUV), and X-Ray instruments to investigate the interaction between the Sun’s magnetic field and its corona.

There’s so much we don’t know about our very own Sun.

Which explains why there are several missions launched to study the Sun. Such as the Solar Terrestrial Relations Observatory (STEREO) mission, which was launched in October 2006, consisting of two identical spacecraft which orbit and capture stereoscopic imaging of the Sun and solar phenomena, such as coronal mass ejections.

The more we know our Sun, the more we know how to protect ourselves from it, whether from solar flares and electromagnetic waves, or from something as basic as protection from UV Rays, which cause sunburn and increases our risk to skin cancer.

Some fun Sun facts

1 July, 2009

Some facts about our one and only Sun.

  • Author: NASAThe Sun is a star.
  • Its vital statistics are: it’s 4.6 billion years old (about middle aged as far as the lifespan of stars go) and weighs a mass of 2 x 1027 tonnes.
  • About 74% of the Sun is hydrogen. 24% is helium. The rest consists of trace amounts of iron, nickel, oxygen, and all other elements. 
  • The solar system consists of the Sun and eight planets, but the Sun pretty much makes the solar system. It accounts for 99.8% of the total mass of the solar system, most of the remaining 0.2% comes from Jupiter.
    Earth and the rest of the planets together make up just a fraction of the solar system’s mass.
  • The temperature of the Sun’s atmosphere reaches about 100,000°C. The temperature at the Sun’s surface, the photosphere, is less at about 6,000°C, but increases as we move inwards towards the Sun’s, which measures about 15 million degrees Celsius!
  • Ultraviolet light from the Sun has antiseptic properties and is used by industries to sanitize tools and water. In our bodies, it helps in the production of vitamin D. However, UV Rays also cause sunburn.

Protect yourself – a reminder in viewing safety

22 June, 2009

Photo: LykaestriaA gentle reminder to all again, if you are gonna catch the upcoming solar eclipse, or any future solar eclipses, please take proper precautions to view it safely.

The safest viewing technique is the pinhole projection method or to use a pinhole camera. Otherwise make sure you use proper solar filters.

Do not look at the Sun or a solar eclipse with your naked eyes.

(And yes, we can just hear you go “Yes, Mum.”)

Looking directly at the Sun, even briefly, can cause temporary blindness, possibly even permanent blindness.

The Sun delivers 4 milliwatts of sunlight to the retina, slightly heating it and potentially causing damage as our eyes cannot respond to the brightness. You could even suffer permanent blindness. Let’s not forget that the Sun is 1.3 million times the size of Earth, and made up of burning nuclear fusion energy.

Photo: NASAThe Sun also exposes us to UV rays. In our eyes, the UV rays yellows the lens and over a period of years cause cataracts. That’s why protective sunglasses are a good investment.

UV rays from the Sun are also what gives us sunburn; the rays reach the layer just under the skin’s surface, damaging the cells there and causing the “burn”. Over time, this could lead to higher risk of skin cancer.

The Sun may be magnificent and necessary for life, but it’s still a powerful force to watch out for.