On July 3, 2025, at 3:54 PM ET, Earth will reach its farthest point from the Sun this year, a phenomenon known as aphelion. The planet follows an elliptical orbit, which means its distance from the Sun fluctuates throughout the year. In contrast, perihelion—the point at which Earth is closest to the Sun—occurs in early January, with the next instance set for January 3, 2026.
At aphelion, the distance between Earth’s center and the Sun’s center will measure approximately 152,087,738 kilometers (about 94,502,939 miles). During perihelion, Earth is roughly 5.1 million kilometers (about 3.2 million miles) closer to the Sun, resulting in a 6.8 percent increase in solar radiation received in January compared to early July.
Interestingly, this variation in distance does not dictate seasonal weather patterns. The tilt of Earth’s axis is the primary driver of seasons. Currently, the Northern Hemisphere is tilted toward the Sun, leading to the summer months, while the Southern Hemisphere experiences winter. In about six months, the situation will reverse, and the Southern Hemisphere will enjoy summer as the Northern Hemisphere faces winter.
The dates of aphelion and perihelion shift over time due to cyclical astronomical processes. Every 58 years, these points move by about one day. Various factors, including the addition of leap days, also contribute to year-on-year variations. Historically, significant moments like New Year’s Day coincided with perihelion in the late 1800s, and during the mid-1200s, solstices aligned with these important dates.
The shape of Earth’s orbit is not static; it is affected by the gravitational influence of Jupiter and Saturn. Over vast timescales, Earth’s orbit has transitioned from slightly elliptical to nearly circular. Currently, the orbit is approaching its most circular state, a development categorized under Milankovitch cycles.
While the geometry of Earth’s orbit changes, the length of the year remains constant due to gravitational laws. As the shape of the orbit fluctuates, the distance from the Sun shifts, causing variations in seasonal length. This means that during certain times of the year, such as spring and autumn, Earth is often closer to the Sun than during aphelion.
The length of each season is further influenced by the orbit’s shape. Seasons are classified astronomically based on Earth’s position within its orbit. At present, summer in the Northern Hemisphere lasts approximately 4.66 days longer than winter, while spring is about 2.9 days longer than autumn. These differences can lead to intriguing effects, as the circular nature of the orbit encourages a more uniform seasonal length.
In summary, aphelion and perihelion illustrate the complex relationship between Earth’s orbit and the seasons. Understanding these celestial mechanics not only sheds light on our planet’s movement but also enriches our appreciation for the dynamic nature of the universe we inhabit. As the Earth continues its journey around the Sun, these cycles will persist, forever shaping the rhythms of our seasons.