Each January, Earth reaches its closest point to the sun, known as perihelion. In 2026, this moment happened on January 3 at 12:15 p.m. EST, when Earth was approximately 91.4 million miles away from the sun. While it may sound important, this event doesn’t really affect our seasons.
Earth follows a slightly elliptical orbit around the sun, which means our distance changes throughout the year. This variation is about 3%, but it plays no role in our climate. Experts, like those at Space.com, stress that it’s the tilt of Earth’s axis that truly dictates our seasonal changes.
What Is Perihelion?
The term “perihelion” comes from Greek, meaning “around the sun.” It denotes the closest point of an orbiting body to the sun. In 2026, Earth’s perihelion was about 147 million kilometers away. In contrast, aphelion, the farthest point from the sun, occurs in early July, when we are about 5 million kilometers further away.
Despite the significant-sounding distance between perihelion and aphelion, this difference is minor on a cosmic scale. The average distance between Earth and the sun is defined as one astronomical unit (AU), approximately 149.6 million kilometers. The energy received from the sun at both points remains nearly the same, so this seasonal distance variation has a negligible effect on our climate.
Experts affirm that, compared to other celestial objects, perihelion can have much more importance. For example, NASA’s Parker Solar Probe takes advantage of its highly elliptical orbit for solar observations.
Historical Insights
Back in 1604, astronomer Johannes Kepler established his first law of planetary motion, demonstrating that planets follow elliptical paths around the sun. This marked a major shift in understanding planetary motion, previously thought to be circular. Kepler’s work was initially influenced by observations of Mars.
Medieval astronomers struggled with solar timing discrepancies. Edward Bloomer from the Royal Observatory notes that early scholars noticed solar days didn’t consistently match theoretical timekeeping. This realization was rooted in the elliptical nature of Earth’s orbit. Instruments like the analemma—a tool plotting the sun’s position over a year—helped them better understand these quirks.
Perihelion in Context
All planets experience perihelion but its impact varies. Planets like Venus and Neptune have nearly circular orbits, while Mercury, closest to the sun, has the most eccentric orbit. According to the Royal Greenwich Observatory, Mercury’s perihelion-aphelion swing is about 0.17 AU, significant for a planet that averages just 0.39 AU from the sun.
An intriguing aspect of perihelion involves Mercury’s orbital precession. Initially, Newtonian physics couldn’t fully explain the small, measurable shift in Mercury’s perihelion over time. This mystery puzzled astronomers until Albert Einstein’s theory of general relativity provided clarity, proving to be one of the theory’s critical tests.
Comets and asteroids also experience dramatic shifts in perihelion due to their high eccentricities. Their orbits can change substantially with each pass, sometimes even leading to their ejection from the solar system after interacting with larger planets like Jupiter.
In summary, while perihelion is an interesting astronomical event, its effects on Earth’s seasons and climate are minimal. Understanding the details of these celestial movements shows us the complexity and beauty of our solar system.
