The Sun on Earth

To the best of our knowledge, our Sun is the only star proven to grow vegetables. Philip Scherrer

Auroras, rainbows, sun dogs, green flashes, sun pillars, sunfish, sunflowers, glorious sunrises -- the Earth is full of wonderous references to the Sun, each inspired by the life-giving force from our special star.

The Sun-Earth Connection

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Auroras | Rainbows | Sunrise, Sunset | Global Warming | Watering with Seawater | The Sun in Nature

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The Majestic Auroras

Image by Don Rice, Fairbanks, Alaska

Named after the Roman goddess of dawn, auroras shimmer and glow in the polar regions of the Earth. What are they and how are they caused? What do they have to do with the Sun? How are the auroras at the North and South poles related? When and why do auroras sometimes frequent lower latitudes? Can we predict auroras? What do auroras look like from spacecraft? Do other planets have auroras?

What does it feel like to experience an aurora for the first time? Read Sten Odenwald's The Cosmologist and the Aurora.

To explore auroras, start with these:

• Physics of ther Aurora by NCAR and the COMET Program
  An interactive learning module that focuses on the physical systems and processes in the Earth's upper atmosphere and magnetosphere that produce these mysterious lightg.
• A web course on the aurora
• Auroras: Self-guided Lesson (The Exploratorium in San Francisco)
• Current Aroral Maps NOAA POES satellite data
• The Aurora Page Michigan Tech
• Auroral Activity Forecast Geophysical Institute, University of Alaska
• The Auroral Oval Marshall Space Flight Center
• The Auroral Observatory University of Tromso, Norway

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Nature's Charming Rainbows

We all know that rainbows are caused by light refracting through raindrops. But do you really understand what that means? Do 2 people standing a ways apart see the same rainbow? Are the colors of a rainbow in any particular order? Why do we sometimes see 2 rainbows, a second fainter one "echoing" the first? How can you make your own rainbow? Are there other ways to break up light into its colors? What does a rainbow look like from a high-flying aircraft (hint: it's not an arch anymore)?

These sites won't tell you all the answers, but here are some places to start:

• About Rainbows
• Rainbows - an overview
• Demonstration of How Rainbows Work
• How a Rainbow Works
• Light, Reflection & Refraction

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Not until 1959 did Parliament revoke a 300-year-old law in Britain that made it a crime punishable by burning at the stake to forecast the weather.

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Sunrise, Sunset, and Other Atmospheric Phenomena

We've all experienced that special moment when our Sun, yellow-orange in the haze, finally sets and leaves our world. But, do you know why the sunset is red, or why the Sun appears "squashed" as it sets? Have you ever seen the green flash just after sunset? Or a sun pillar just before dawn?

The Sun and our atmosphere are a magical and mischievous team, often trying to trick us with unlikely appearances. Explore more about white sunsets, mirages, a blue sun at noon, silver linings, sun halos, Glories, and why our sky is blue (and Mars' isn't). (Image Credit: National Park Service. NOAA Photo Library.)

More on Atmospheric Optics

Image Credit: Linda Brown

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Global Warming

Global warming -- a gradual increase in planet-wide temperatures -- is now well documented and accepted by scientists as fact. A panel convened by the U.S National Research Council, the nation's premier science policy body, in June 2006 voiced a "high level of confidence" that Earth is the hottest it has been in at least 400 years, and possibly even the last 2,000 years. This warming is largely attributed to the increase of greenhouse gases (primarily carbon dioxide and methane) in the Earth's upper atmosphere caused by human burning of fossil fuels, industrial, farming, and deforestation activities.

Some uncertainty remains about the role of natural variations in causing climate change. Solar variability certainly plays a minor role, but it looks like only a quarter of the recent variations can be attributed to the Sun. At most.

Want to learn more? Visit our global warming page.

Image Credit: Environmental Protection Agency. NOAA Photo Library

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Nature

Photo courtesy of Mike Johnson	Amongst the fishes of the sea, the Sunfish ("Mola mola") is most likely the strangest. Named for its habit of laying on its back near the surface to "sunbathe", this gentle giant resembles a fish designed by committee -- squarish, missing a tail, and its fins are in the wrong place! Most fish do not lie on their sides to sunbathe. Why do you think the Sunfish does?
	The Sunflower is reknown for its ability to track the sun throughout the day. How do you think it does this? Some sunflowers live near the polar regions, where their "day" is 6 months long. Do you think they "spin down" when their sun finally sets?
	The Sun Scorpion. Despite their common name, Sun Scorpions are not scorpions and they shun the sunlight, preferring to hunt at night. They are also called wind scorpions because they appear to run as fast as the wind. They are sometimes called camel spiders or sunspiders after their sunny desert habitat. Image credit: Royal BC Museum