Resumen de Ask the experts.

Steven Allison, Jeff Waldstreicher

• This article presents questions and answers related to science. One person asks why most of the ground is brown; Steven Allison of the University of California, Irvine, says carbon in inorganic forms absorb most wavelengths of light and give soil its brown shades. Another person asks why rainbows form instead of straight bands of colors; Jeff Waldstreicher of NOAA's National Weather Service says rainbows form through refraction, which is the bending of light, making light turn as it goes through raindrops.