On January 4, 2025, Earth will reach its closest point to the Sun, an event known as Perihelion Day. Occurring annually, this phenomenon takes place every January, providing insight into the planet's elliptical orbit.
During perihelion, Earth will be approximately 147 million kilometers from the Sun. Although the Sun may appear slightly larger in the sky, this change is nearly imperceptible. This year, perihelion will occur at 8:28 a.m. EST.
The term 'perihelion' is derived from the Greek words 'peri' (near) and 'helios' (Sun). This event generally occurs between January 2 and 4, shortly following the December solstice. Conversely, the aphelion, or the farthest point from the Sun, occurs in early July.
Despite the proximity to the Sun, temperatures in the Northern Hemisphere remain low during this time. The axial tilt of Earth, rather than its distance from the Sun, dictates seasonal weather patterns. At perihelion, the Northern Hemisphere tilts away from the Sun, leading to cooler conditions despite increased solar radiation.
Earth's orbit is elliptical and not a perfect circle. Its shape, or eccentricity, changes over time due to gravitational influences from the Moon and other celestial bodies. Every 100,000 years, the orbit fluctuates between nearly circular and more elliptical.
This variation in Earth's orbit plays a significant role in climatic patterns, although it has minimal effect on the Sun's apparent size. For astronomers and enthusiasts, perihelion presents a unique opportunity to reflect on Earth's journey through space.