Earth's orbit is almost a perfect circle - only 1.67% off - yet the Sun-Earth distance still swings by about 5 million km each year. Scrub the day-of-year slider to watch it happen.
Published figures: mean Sun-Earth distance 149,597,870 km (1 AU); perihelion about 147.1 million km in early January; aphelion about 152.1 million km in early July; orbital eccentricity 0.0167 (NASA NSSDCA planetary fact sheet, Old Farmer's Almanac).
Drag to orbit and scroll or pinch to zoom. Scrub the day-of-year slider, press Play year, or jump straight to perihelion or aphelion.
Earth Perihelion & Aphelion 3D Explorer
This browser explorer shows how far Earth actually is from the Sun on any day of the year: scrub to early January and Earth is at perihelion, about 147.1 million km away; scrub to early July and it is at aphelion, about 152.1 million km away - a swing of roughly 5 million km even though the orbit itself is almost a perfect circle.
Earth's orbital eccentricity is only 0.0167, so the ellipse drawn in the 3D view looks nearly circular - that is the real shape, not an error. The distance curve below the scene makes the swing visible: Sun-Earth distance rises and falls smoothly across the year, following Kepler's laws, calibrated to the published perihelion and aphelion figures.
- Scrub the day-of-year slider or press Play year to watch a full orbit
- Jump straight to perihelion (closest, early January) or aphelion (farthest, early July)
- Read the live Sun-Earth distance in millions of km and millions of miles
- See how much extra solar energy Earth receives at perihelion versus aphelion
- Drag to orbit, scroll or pinch to zoom
- Runs fully in the browser with the vendored three.js engine - no account, no upload
| Figure | Published value |
|---|---|
| Mean Sun-Earth distance (1 AU) | 149,597,870 km (92,955,807 mi) |
| Perihelion (closest, early January) | about 147.1 million km (91.4 million mi) |
| Aphelion (farthest, early July) | about 152.1 million km (94.5 million mi) |
| Distance swing | about 5 million km, about 3.3% of the mean distance |
| Orbital eccentricity | 0.0167 (nearly circular; 0 would be a perfect circle) |
| Extra solar flux at perihelion vs aphelion | about 7% more (flux follows 1 over distance squared) |
Here is the counterintuitive part: perihelion falls in early January, during Northern Hemisphere winter, and aphelion falls in early July, during Northern Hemisphere summer - the opposite of what "closer to the Sun means hotter" would predict. Distance is a minor factor at most; axial tilt (23.44 degrees) is what actually drives the seasons, tipping each hemisphere toward or away from direct sunlight. See the Seasons Explorer for that mechanism in detail.
For the general ellipse mechanics behind any orbit - not just Earth's - including Kepler's equal-area law and adjustable eccentricity, open the Kepler Orbits 3D Explorer.
Everything renders on your device with WebGL. The 3D engine loads once (about 0.7 MB) and is cached.
This is an educational approximation - the distance curve is a smooth Keplerian model calibrated to the published perihelion and aphelion values, not a day-by-day ephemeris, and the 3D orbit view is not to scale in overall size (only the ellipse shape - the eccentricity - is drawn accurately).
Frequently Asked Questions
What is perihelion and aphelion?
Perihelion is the point in Earth's orbit closest to the Sun, about 147.1 million km away, reached in early January. Aphelion is the point farthest from the Sun, about 152.1 million km away, reached in early July.
Why isn't perihelion in summer if Earth is closer to the Sun?
Because distance is not what causes the seasons. Earth's 23.44-degree axial tilt is what drives them - it tips each hemisphere toward or away from direct sunlight over the year. Perihelion (early January) happens to fall during Northern Hemisphere winter, and aphelion (early July) during Northern Hemisphere summer - the opposite of "closer means hotter."
How elliptical is Earth's orbit really?
Very slightly - the eccentricity is only 0.0167, where 0 would be a perfect circle. On screen the orbit looks almost circular because that is genuinely close to its real shape; the 5-million-km distance swing comes from a small deviation, not a dramatically stretched ellipse.
Does Earth get more sunlight at perihelion?
Yes - solar flux follows an inverse-square law, so Earth receives about 7% more solar energy at perihelion than at aphelion. This slightly moderates Southern Hemisphere summers and Northern Hemisphere winters, but it is a minor effect compared to axial tilt.
Does the perihelion date change every year?
Yes, slightly. The exact date can drift by up to about 2 days from year to year due to the calendar's leap-year cycle and slow changes in Earth's orbit, but it always falls in the first days of January.
Is this a real-time simulation of today's Earth-Sun distance?
No. It is an educational explorer using a smooth Keplerian model calibrated to the published perihelion and aphelion figures, not a live ephemeris or tonight's exact position.