The tilt of Earth's axis causes the apparent position of continents to shift with the seasons. Most people learn in elementary school that the seasons are caused by Earth's rotation on a tilted axis as it orbits the sun. This tilt, approximately 23.5 degrees, is believed to have been caused by a massive collision with a planetary body called Theia about 4.5 billion years ago, the same event that led to the formation of the moon. To visualize this, imagine Earth as a spinning top tilted to one side. During the June solstice, the Northern Hemisphere tilts toward the sun, receiving more direct sunlight and experiencing longer days. During the December solstice, the Southern Hemisphere tilts toward the sun instead. This is why the Northern Hemisphere experiences summer in June and the Southern Hemisphere does so in December. The March and September equinoxes mark the midpoint between these extremes. On these days, the terminator—the line between the sunlit and dark sides of Earth—passes through both poles, resulting in nearly equal day and night lengths across both hemispheres. NASA's EPIC (Earth Polychromatic Imaging Camera), aboard the DSCOVR (Deep Space Climate Observatory) satellite, provides a view of Earth from about 1 million miles away. The spacecraft maintains an orbit that keeps it between the sun and Earth, allowing EPIC to continuously capture images of the sunlit side of our planet. As Earth rotates, EPIC takes a full-disk image of the planet every few hours. Four images from EPIC show how the view of the Western Hemisphere changes over the course of a year, from the December solstice to the March equinox, June solstice, and September equinox. The most noticeable difference is between the two solstices. In December, South America is near the center of the image, and Antarctica is visible, while North America is partially out of view. In June, the situation is reversed: the Northern Hemisphere and North America are more centered, Arctic sea ice becomes visible, and Antarctica is completely out of view. There are other subtle differences in the images. For example, Earth appears slightly smaller during the equinoxes because the DSCOVR satellite was farther away from Earth on those dates compared to the solstices. This change in distance is not due to Earth's tilt but is a result of the spacecraft's orbit. DSCOVR follows a looping, three-dimensional path known as a Lissajous orbit, keeping it near a gravitational balance point called Lagrange point 1. This orbit allows the spacecraft to remain in position with minimal fuel use. The distance between DSCOVR and Earth fluctuates roughly every three months, and the timing of these fluctuations can shift slightly each year due to lunar influences and orbital adjustments. Another difference is the angle between the sun, Earth, and the satellite, which varies between 2 and 12 degrees. This variation affects how Earth appears in the images. At smaller angles, Earth appears fully illuminated, while at larger angles, it looks less rounded, like a "bite" has been taken out, similar to the gibbous phase of the moon. For instance, the September equinox image shows a slightly lower angle than the December solstice image, making Earth appear slightly rounder and fuller. While these changes are subtle, they highlight the complex orbital dynamics at play. However, the most obvious changes—such as the apparent location of continents—are due to Earth's tilt. EPIC's vantage point not only helps visualize the cause of seasons but has also provided over a decade of data on Earth's daily and seasonal cycles, offering new insights into features like vegetation, clouds, ice, snow, UV radiation, ocean color, and aerosols.