Can the sun kill you?

By: Charles W. Bryant
Sun Image Gallery The sun is giant ball of burning gas. See more sun pictures.
Pat Powers & Cherryl Schafer/Getty Images

Anyo­ne who's ever made it through the fifth grade can probably tell you that the sun is a star. It's one of the cooler early facts a kid learns, mainly because the sun do­esn't look anything like­ other stars -- at least not to the naked eye. The sun looks so much different because of its proximity to Earth. It's much closer than other stars, which makes it look like the bright, burning ball of gas that it is, rather than a tiny light twinkling in the distant darkness. We're talking close in a universe kind of way -- 93 million miles (150 million kilometers) from Earth to be exact [source: High Altitude Observatory].

The sun is also huge -- if it were a hollow sphere, more than one million Earths would fit inside of it. And if you were to take a car trip to the sun, it would take about 176 years to get there if you drove 60 miles per hour (96.5 kph) all day, every day [source: High Altitude Observatory]. That's one heck of a road trip. Luckily for the Earth, the sun comes to us. It takes about eight mi­nutes for light from the sun to reach us. That light, heat and energy are essential to our existence. Without the sun, Earth would be a big, dark, lifeless frozen sphere hurtling through the universe.


­The sun has been shedding light and energy on Earth for about 4.5 billion years, even though humans have only been around to enjoy a fraction of it. And while it provides us with life, it can also ­be dangerous. After all, the center of the sun burns at roughly 10 million degrees Fahrenheit (5.5 million degrees Celsius). That's a lot of heat, and if you're not careful, it can cause a lot of damage. Looking directly at the sun, even for a few minutes, can permanently blind you. Not only that, but the sun can actually kill you in certain circumstances.

Risk of Heat Stroke

Heat stroke is common for desert hikers, and it can kill you.
Sylvia Otte/Getty Images

One way tha­t the sun can kill you is by giving you a heat stroke. This is when your body is unable to cool itself down, and your body temperature rises above 104 degrees Fahrenheit (40 degrees Celsius). The human body has its own built-in cooling system. When we get overheated, we get rid of the excess heat by sweating. Under normal conditions, even when it's really hot, this temperature control mechanism does the job. But sometimes even a heavy sweat won't do the trick, and the body begins to overheat. The process from this point goes from heat cramps to heat exhaustion and finally to heat stroke.

Each of these is counted as its own heat-related illness, and they're all treated the same. You need to get cooler, plain and simple. Shade, air conditioning and drinking plenty of cool water can typically stop the overheating process at the cramping and exhaustion phase. If you're unable to cool yourself, heat stroke will be next. You'll know you're having a heat stroke if you notice the following:


  • Hot, red and dry skin
  • Strong, rapid pulse
  • Headache
  • Dizziness
  • Hyperventilation
  • Confusion
  • Nausea
  • Seizures
  • Hallucinations
  • Unconsciousness

If you're unable to cool down, you can actually die from heat stroke. Many times, shock will set in, which can cause damage to your major organs. Even if you don't fall into shock, your overheated body will cause your internal organs to swell, leading to serious internal damage and potential death.

The most likely candidates to be killed by heat stroke are the very young and the elderly. Infants up to four years old strapped into a parked car in the sun are at a very high risk because of the extreme heat and the fact that they can't care for themselves. The elderly are affected in the same way -- sometimes the heat stroke comes on so quickly that they aren't able to combat it in time.


Skin Cancer Risks

Don't forget the nose
Sunscreen can save your life and is loads of fun to apply with a friend!
Simon McComb/Getty Images

Another wa­y the sun can kill you is through skin cancer. The sun emits light in many different wavelengths. The one that humans need to worry about are ultraviolet (UV) light waves. We can't see this wavelength with our eyes, mainly because they're shorter waves than visible light. If you've ever bought a nice pair of sunglasses, they probably claim to block out 100 percent of UV rays. This doesn't mean you can look at the sun, but it does protect your eyes while you're outside in the daytime.

These UV rays are also the way you can get skin cancer. While you might like the way you look with a tan, it's actually a sign of skin damage from UV rays. In fact, most all of the changes to your skin are from UV exposure, including wrinkles and freckles. There are springy, fibrous proteins in the skin called elastin that help keep the skin flexible and tight. Over the years, damage to the elastin from UV exposure causes it to break down. This can lead to pre-cancerous or cancerous skin lesions or tumors.


Like all cancers, skin cancer is a result of the growth of abnormal cells -- in this case, skin cells. It's the most common kind of cancer and there are three main types:

  • Basal cell carcinoma
  • Squamous cell carcinoma
  • Melanoma

The first two kinds aren't very serious and make up about 95 percent of all cases of skin cancer. Melanoma is very serious and accounts for 75 percent of skin cancer deaths [source: WebMD]. Doctors will tell you that exposure to the sun's UV rays is the number one cause of skin cancer, making it one of the more preventable forms of cancer. It should also be noted that UV rays from tanning beds are just as dangerous.

You can help to prevent skin cancer by staying out of the sun between the peak hours of 10 a.m. and 3 p.m., or taking extra precautions if you can't avoid prolonged UV exposure. Sunscreen with a sun protection factor (SPF) of at least 15 is mandatory to help shield you from the harmful UV rays. If you're a parent, take care of your children's needs -- 80 percent of your lifetime's UV exposure comes before the age of 18 [source: WebMD].


Xeroderma Pigmentosum

Sadly, children with xeroderma pigmentosum can only play outside under the light of the moon.
Simon McComb/Getty Images

There's a rare skin disorder that's almost certain to kill you. It's called xeroderma pigmentosum (XP), and it only affects one out of every million people. A person who is stricken with XP is highly sensitive to sunlight -- so much so that they can never go outside during daylight hours. It's a cruel disorder that ends up claiming most of those afflicted by middle age, typically from skin cancer. The disorder is caused by a defect in the genes, so it's inherited at birth. It's rare because a child needs to inherit the gene from both parents.

UV exposure is the killer in this case, and it doesn't have to come from direct sunlight. Any kind of indirect exposure to the sun's rays or even UV light from fluorescent light bulbs can cause serious damage. There are only about 250 documented cases in the United States and most of them are children. If you have XP, you're more than 1000 times as likely to develop skin cancer as someone without it [source: Free]. That number could even be as close as 2,000 times as likely [source: Xeroderma Pigmentosum Society].


Sufferers of XP are forced to take great precautions throughout their lifetime. House windows are retrofitted with UV blocking tinting, and days are spent indoors for the most part. To a large degree, many people switch their daytime and nighttime habits and activities since each and every UV exposure causes cumulative and irreparable damage. The disorder is typically caught between one and two years old, and there is no cure. Some of the early warning signs are blistering and freckling from minimal exposure to the sun and premature aging of the lips, eyes, skin, mouth and tongue.

There is some hope for children who think they can never go outside and enjoy the daylight hours. NASA has developed a special "cool suit" similar to the ones used for space missions that is an effective UV blocker. The suit is pricey -- at $2,000 -- but it blocks 99.9 percent of UV rays and has allowed some children to play outside for the first time in their lives.


Lots More Information

Re­lated HowStuffWorks Articles
  • How the Sun Works
  • How Sunglasses Work
  • ­How Solar Eclipses Work
  • How Sunburns and Sun Tans Work
  • How Cancer Works
  • How the Immune System Works
  • How Cells Works
  • How Blood Works
  • What causes heat stroke?
More Great Links

  • "About the Sun." National Center for Atmospheric Research. 2009.
  • "Cosmetic Procedures: Sun Exposure and Skin Cancer." WebMD. 2009.
  • "Dehydration and Heat Stroke." University of Maryland Medical Center. 2009.
  • "Frequently Asked Questions (FAQ) About Extreme Heat." Centers for Disease Control and Prevention. 2009.
  • "Heat cramps: First aid." Mayo Clinic. 2009.
  • "Heat exhaustion: First aid." Mayo Clinic. 2009.
  • "Heatstroke." Mayo Clinic. 2009.
  • "Ultraviolet Waves." NASA. 2009.
  • "What is Xeroderma Pigmentosum?" 2009.
  • "XP." Xeroderma Pigmentosum Society. 2009.
  • Free, Cathy. "Paris by Moonlight." Reader's Digest. 2009. makes-the-sun-deadly/article28507.html