My second floor office overlooks a delightful pedestrian mall lined with restaurants and shops. Strategically placed outdoor benches entice patrons and passersby to linger, converse and savor the ambience of a Midwestern college town. In the spring and fall, it is a venue filled with music, conversation and laughter.
Alas, as the continental United States remains in the ironfisted grip of a seemingly endless, harsh winter, the benches are snow covered and empty. The bundled pedestrians stride wearily forward, eyes squinted in a thousand yard stare as they seek solace from the prairie wind and cold. As Frost poetically observed, they have promises to keep, and miles to go before they sleep.
Trust the Science
Though the long past, languid days of northern latitude summer now seem like a waking dream, I have faith – grounded in science – that summer will come again. This oblate spheroid of revolution (aka a reference ellipsoid) we call planet Earth will again bring the warmth of summer to northern climes. (We can thank Isaac Newton's Principia for the proof that a rotating self-gravitating fluid body takes the form of an oblate spheroid of revolution.)
All of us are tempted to believe that seasonal variations are due to the varying distance of the Earth from the sun – its orbital eccentricity. It seems intuitive and obvious, but it is incorrect. The eccentricity of the Earth's orbit is quite small. Even more interestingly, the Earth is closest to the Sun on January 3, the periapsis of its orbit. The real cause of the seasons is the 23.5-degree axial tilt of the Earth relative to its orbital plane around the sun.
As the Earth orbits the sun, its tilted axis always points in the same direction. During part of the year, the northern hemisphere (that's us) is tilted toward the sun, yielding longer days and more direct sunlight; that is our summer. During our winter, the southern hemisphere tilts toward the sun, giving it summer and a now frigid winter to those of us in the north. As Newton showed and Einstein later expanded, in a few months, gravity and orbital mechanics will bring summer back again. A helpful NASA cartoon explains why this is the case.
STEM Education Really Matters
If you did not know the orbital cause of the seasons or had forgotten it, then you are in good company. In a famous, some might say infamous, 1987 study, a group of education researchers asked newly minted Harvard graduates to explain the cause of the seasons. As this brief video shows, most of them answered incorrectly, despite years of K-12 and college-level science and mathematics classes.
As my friend, Neil deGrasse Tyson, once wryly remarked, "The good thing about science is that it's true whether or not you believe in it." Natural processes proceed with or without our understanding, but they are discoverable via systematic application of the scientific method – formulating hypotheses and testing them via repeatable and verifiable experiments.
I am not suggesting that everyone should be a scientist or engineer. A detailed understanding of celestial mechanics will not affect your job prospects (unless you are an aspiring astronomer), but in a global economy, a working knowledge of basic science, engineering and mathematics and a systematic approach to problem solving certainly will. Equally importantly, public policy issues, whether in health care, transportation, communications or energy, increasingly rest on scientific principles and shared understanding that must inform our collective debate and decision-making.
In technology-driven world, effective Science, Technology, Engineering and Mathematics (STEM) education is crucial for all of our students. We must do a better job of inculcating fundamental scientific principles and their practical applications, moving science and mathematics education beyond dry facts and formulas to vibrant and predictive experiential learning. Science education, when done right, is fun, filled with joy and passion for discovery and understanding. That's one of the great beauties of science; anyone can apply the scientific method and independently verify scientific claims.
Spring will come again, as surely as the Earth orbits the sun. Meanwhile, I am counting the days until the vernal equinox brings the sound of laughter back to the pedestrian mall.