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Perihelion Day occurs every January, marking the point in Earth’s elliptical orbit when our planet is closest to the Sun. It’s a fascinating reminder of the celestial mechanics governing our solar system. Discover more about this annual astronomical event and explore the science behind it.
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Expected Perihelion Day Deals
While Perihelion Day isn’t a traditional shopping holiday, science enthusiasts can find deals on related items. Look for discounts on telescopes from brands like Celestron and Meade Instruments, offering a clearer view of the cosmos. Educational retailers such as National Geographic Store and Discovery Store often feature sales on astronomy kits, globes, and space-themed books. Online course platforms like Coursera or edX might offer promotions on astrophysics or planetary science courses. We will update this page with confirmed live deals as January approaches.
Platform Guide for Perihelion Day
Tag @nationaltoday_ and use #PerihelionDay. Share stunning space photography or infographics explaining Earth’s orbit.
TikTok
Tag @www.nationaltoday.com and use #PerihelionDay. Create short, engaging videos explaining perihelion and aphelion with visual aids.
X/Twitter
Mention @NatlToday and use #PerihelionDay. Share breaking astronomy news, facts about Earth’s orbit, and scientific discussions.
Perihelion Day Hero
Johannes Kepler
History of Perihelion Day
Perihelion is an astronomical occurrence that happens around two weeks from the December Solstice. Even though it is winter in the Northern Hemisphere during this period, Earth reaches the closest point of over 91 million miles to the sun on this day. Perihelion does not directly affect Earth’s temperature; it does not make us feel any warmer, nor does it provide respite from the chilling temperature. However, it does indirectly affect seasons because Earth’s orbital speed is at its maximum at perihelion. On this day, the sun appears the largest in the sky for the entire year, gradually growing smaller through the remainder of the year.
In 1246, Perihelion Day was on the December Solstice. Every 58 years since then, the date has changed by a day. Perihelion Day varies each year due to precession and orbital factors that follow specific cyclical patterns known as the Milankovitch cycles. Another cause is the moon’s presence, which can make the date vary by up to two days from one year to another. While the Earth-Moon barycenter moves on a stable orbit around the sun, Earth’s center, which is around 2,900 mi from the barycenter, can shift in any direction from it, thus affecting the actual time of the perihelion.
In 2000, the longitude of the perihelion was about 282.895°, and by 2010, it had become around 283.067°. According to astronomers, in the year 6430, the perihelion will happen simultaneously as the March Equinox.
Perihelion Day timeline
Johannes Kepler coins the terms ‘Perihelion’ and ‘Aphelion.’
Johannes Kepler and Isaac Newton discover the basic planetary laws which the orbits follow.
It is observed that Mercury's perihelion shift is different by about 43 arcseconds per century from what the classical gravitational theory predicted.
Albert Einstein’s general theory of relativity gives a more detailed description of Kepler's orbit laws.
Earth is observed in transit from Mars across the solar disk.
Sumich, J.L., reports that during Earth’s perihelion, the tidal ranges are enhanced.
Perihelion Day FAQs
When is Perihelion Day?
Perihelion Day 2026 falls on Saturday, January 3, when Earth reaches its closest point to the Sun in its elliptical orbit.
What is perihelion?
Perihelion is the point in the orbit of a planet, asteroid, or comet where it is closest to the Sun. It is the opposite of aphelion, which is the point where the object is farthest from the Sun.
How far is Earth from the Sun at perihelion?
At perihelion, Earth’s center is approximately 91.4 million miles (147.1 million kilometers) from the Sun’s center. This is about 3 million miles closer than its average distance.
Why is Earth closest to the Sun in winter?
Earth is closest to the Sun during the Northern Hemisphere’s winter because the seasons are determined by the tilt of Earth’s axis, not its distance from the Sun. When the Northern Hemisphere tilts away from the Sun, it experiences winter, even though the Earth is at perihelion.
How to Observe Perihelion Day
Read about astronomy
Many astronomical events occur that we are not aware of and don’t understand. For instance, if perihelion means Earth is closest to the sun, it should also mean we would experience hotter temperatures, right? Wrong. This occurrence falls during winter! Brush up on your astronomy to understand the science behind this.
Do a science project
This day can be an excellent excuse to do a little science project just like the old days. Make cardboard cutouts of the sun and the earth, and show how planet Earth is closest to the sun on this day. It will be a fantastic way for kids to learn science.
Visit a planetarium
Planetariums offer a unique experience of space without going to space, which is quite tricky if you’re not an astronaut. Visit a planetarium on Perihelion Day, view planets from a telescope, attend a show about the planets and stars, and learn more about how the galaxies function.
5 Important Facts About Perihelion
A Greek word
The name comes from the Greek words ‘peri’ (near) and ‘helios’ (sun).
The aphelion is the exact opposite
The opposite of perihelion is aphelion, which is when Earth is farthest from the sun.
Distance is still very far
The difference in distance between Earth's nearest point to the sun in January and the farthest point from the sun in July is 3.1 million miles, only a 7% difference.
Seasons during the Perihelion
On perihelion, it is winter in the northern hemisphere and summer in the southern hemisphere.
It affects the seasons in some way
Perihelion doesn’t make the seasons happen, but Earth moves faster as it gets closer to the sun, which means a five-day shorter winter in the Northern Hemisphere and summer in the Southern Hemisphere.
Why Perihelion Day is Important
It’s a remarkable astronomical occurrence
The earth's closeness to the sun is a rather unique event, happening only once a year. Many such instances occur in space that affect the way our planet works.
It teaches us about the seasons
We learn that even though the earth is closest to the sun, we don’t experience blazing hot temperatures during this holiday. Due to the earth’s tilted axis, it does not affect the seasons directly. The northern hemisphere will be wearing layers of clothes to keep warm from the freezing temperatures today.
We appreciate the professionals
Determining the perihelion or any other astronomical event isn’t easy. It requires a great deal of calculation and work. Highly qualified astronomers and mathematicians have to work with utmost precision and clarity to determine such occurrences.
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