This Topic in Depth explores the Web's offering related to the science of the spring season. The first site -- Seasons, Equinoxes, Solstices, and Climate (1) -- is offered by Assistant Professor of Physics and Astronomy, Eric G. Blackman of the University of Rochester. Visitors can learn how the earth's axis and orbit causes the seasons and what the equinox and solstice are, as well as about astronomical effects on the Earth's climate. The second Web site tackles similar issues, but at a more elementary level. Seasons Reasons (2), from ScienceU.com, explains what causes the seasons to change, and provides informative graphics of the Earth's orbit and axis angle during the various seasons. Next, from MSNBC News, comes the Mysteries of the Universe: What Causes Earth's Seasons (3) Web site. The highlight of this site is the well-designed and informative graphic at the top of the page that concisely explains the cause of the seasons. Other portions of the site include the history of our understanding of these topics, a description of the vernal and autumnal equinox, and more. The fourth site related to spring is offered by The University of Illinois Extension called There is a Season (4). The site describes how the sun rises and sets differently throughout the year, and provides two simple but well designed lesson plans related to this topic called I See the Light and Grab Some Rays. The next Web site focuses on a different spring science phenomenon specific to lakes called What is Lake Turnover? (5). Maintained by the Missouri Department of Conservation, the site (although a bit graphically uninteresting) gives an informative description of what spring lake turnover is and what causes it. The sixth site, also dealing with lake turnover, is provided by the Sea Education Association. This well-designed site offers a student activity that demonstrates this process, which is called Density Dynamics (6). The introduction explains that bodies of water form layers based on differences in density affected most by temperature in fresh water and both temperature and salinity in salt water. Using beakers filled with water of varying temperatures and food coloring, students observe what happens when these fluids are mixed in order to better understand what happens naturally in lakes. From the National Institute of Standards and Technology comes the Saving Time, Saving Energy: Daylight Saving Time, its History, and Why We Use It (7) Web site. Visitors can learn how seasonal daylight changes caused the US to adapt daylight saving time as early as 1883 and how its use has progressed throughout the world. The last Web site, offered by the Punxsutawney Groundhog Club, contains information on the weather predictions of Punxsutawney Phil and is called Phil's Past Predictions (8). The site chronicles the "famous" groundhog's predictions, which historically have been used to determine the coming of spring by whether or not it sees its shadow. Visitors will find a list of every year's results, its accuracy, and various other links relating to the groundhog's exploits.