The idea that Alaska is closer to the Sun during the summer is a common misunderstanding that confuses the reason for warmer temperatures with physical proximity. Alaska is not closer to the Sun in summer; in fact, the entire Northern Hemisphere is generally farthest from the Sun during its warmest season. The planet’s varying distance from the Sun has a negligible effect on Earth’s temperature compared to the tilt of our planet.
Understanding Earth’s Elliptical Orbit
Earth’s path around the Sun is an ellipse, meaning the distance between the Earth and the Sun constantly changes throughout the year. Astronomers define two points along this path: perihelion and aphelion.
Perihelion is when the Earth is closest to the Sun, occurring consistently in early January. Conversely, aphelion is the point where the Earth is farthest from the Sun, happening in early July. Therefore, the Northern Hemisphere, including Alaska, is actually at its greatest distance from the Sun during the summer months.
The difference in distance between these two points is approximately 3.1 million miles (5 million kilometers). At perihelion, the Earth is about 91.4 million miles from the Sun, compared to about 94.5 million miles at aphelion. This relatively small variation in distance is not the primary driver of seasonal temperature changes.
Why Surface Location Doesn’t Affect Solar Proximity
The question of a specific location like Alaska being closer to the Sun than other places is a matter of scale. The average distance from the Earth to the Sun is approximately 93 million miles (150 million kilometers). This immense distance makes any difference in latitude on Earth completely insignificant.
The diameter of the Earth is only about 7,926 miles (12,756 kilometers). Comparing the Earth’s diameter to the 93-million-mile distance to the Sun shows that all points on the planet are essentially the same distance from the Sun at any given moment. Whether standing in Alaska or at the equator, the distance to the Sun is practically identical.
A few thousand miles of latitude difference is negligible in the context of the vastness of space between the Earth and the Sun. The concept that one spot on Earth could be significantly closer to the Sun than another due to its location on the surface does not align with astronomical measurements.
The True Determinant of Temperature: Solar Angle and Axial Tilt
The true reason for seasons and temperature differences is the Earth’s axial tilt, which is approximately 23.5 degrees. This tilt causes the Northern and Southern Hemispheres to alternately lean toward or away from the Sun as the planet orbits. This leaning changes the angle at which sunlight strikes the Earth’s surface, known as the angle of incidence.
When the Northern Hemisphere is tilted toward the Sun in summer, the Sun’s rays hit places like Alaska at a steeper, more direct angle. This direct angle concentrates solar energy over a smaller surface area, leading to more intense heating and warmer temperatures. The steeper angle also means the sunlight travels through less of the atmosphere, reducing energy lost to scattering.
Conversely, during the winter, the Northern Hemisphere is tilted away from the Sun. Sunlight hits Alaska at a shallow, oblique angle, spreading the same amount of solar energy over a much larger area. This diffused energy results in lower temperatures, despite the planet being closer to the Sun at that time. The axial tilt also dictates the length of the day, with summer experiencing longer periods of sunlight that contribute significantly to seasonal warmth.