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Here comes the sun: Rising early, staying late

June 7, 2007 12:35 am

WHAT GIVES US life-sustaining light and heat completely free of charge?

The answer is the sun, of course! We celebrate its dominance during June in the northern hemisphere, with the first day of summer June 21.

(When you're celebrating, don't make the mistake of looking directly at the sun--it can permanently damage your vision.)

Did you know that the sun is the closest star to the Earth? Yes, the sun is a star like many others we see in the night sky, but it is also unique in its own right.

Its distinction lies in the fact that it shepherds several planets; one of those, our planet Earth, harbors life.

As far as we know, intelligent life on our planet is an exclusive circumstance in the universe. Our ancestors built structures to worship, honor, and study the sun, and we measure a year based upon the Earth's orbit around it.

The sun is so large compared to our little planet that over a million Earths could fit inside of it. However, it is just an average-sized star compared to others in our galaxy.

It is the brightest object in the sky because the Earth is so "close" to it. Its average distance from the Earth at 93,000,000 miles, called an astronomical unit, is a safe enough gap for life to flourish on our planet.

If you could drive to the sun at a constant highway speed of 60 mph, it would take you about 177 years to get there, and that does not include any bathroom breaks! If you don't feel like driving, an airplane flight would take about 25 years.

The light we receive from the sun has traveled to the Earth at 186,000 miles per second, which is much faster than our imaginary trips in a car or airplane. Sunlight takes a little over eight minutes to reach the Earth. This means that if the sun were to stop shining as you read this, it would take a little more than eight minutes for us to notice the change.

Astronomers have estimated the sun to be about 10,000 degrees Fahrenheit at its surface and about 27 million degrees Fahrenheit at its core. That is some serious heat!

Most notably, the sun influences our weather, climate, ocean currents, and in conjunction with the Earth's tilt, makes our seasons change. Plants grow from sunlight using photosynthesis, and we humans depend on plants and animals for food.

Without the sun, most life on Earth would die. However, there is no need to worry about its energy output as it still has a few billion years' worth of life-sustaining light and heat for us.

Besides light and heat, the sun also emits an invisible stream of particles known as the solar wind. The solar wind can play havoc with radio communications, earth-orbiting satellites and our electrical systems. The solar wind can also create spectacular displays of the aurora borealis, better known as the Northern Lights. They are rarely seen in Fredericksburg, but they are very common well to the north of our area.

So, as you enjoy the warmth of summer this month, remember that the sun is not just an ordinary bright star in the night time.

If you want to learn about an international mission to study the sun, go to nasa.gov/mission_pages/ solar-b/ and discover the Hinode mission.

June features the longest days and shortest nights of the year. However, that should not preclude you from venturing outside after dark to find some bright lights in the summer sky.

Venus continues to be an impressive object in the western sky after sunset. If you want to view a pretty trio of objects, the moon will be between Venus and Saturn on June 18.

The planet Jupiter is well-placed this month and features its best views of the year as it rises in the southeast after the sun sets in the west. You can find it as the unmistakably bright, starlike object near the moon during the evenings of June 26-28.

The Rappahannock Astronomy Club hosts monthly star parties where you can view the moon, planets, and other celestial objects through amateur telescopes. For more information, go to http://www.raclub.org/