Earth orbits the Sun in a flat plane called the ecliptic plane. But Earth's axis is tilted 23.44° relative to this plane. That tilt gives us seasons — and it also means one point on Earth's surface is always "higher" above the ecliptic plane than any other.
That point is the Ecliptic Apex: the spot on Earth's surface that, at any given moment, extends farthest above the plane of our orbit around the Sun. This app computes and tracks it in real time.
Neither the North Pole nor Mt. Everest is, from this perspective, the top of the world. The North Pole is too close to Earth's spin axis and too far from the ecliptic zenith. Everest is the tallest mountain, but at 28°N it's nowhere near the right latitude. The true "top of the world" — the point farthest above our orbital plane — is a remote nunatak in East Greenland.
Because Earth is tilted. The direction that points "up" from the ecliptic plane is called the Ecliptic North Pole (ENP). It is fixed relative to the stars, tilted 23.44° away from Earth's geographic North Pole. As Earth rotates, the ENP direction sweeps around a circle in Earth's reference frame, tracing out a cone at about 66.56°N latitude (= 90° − 23.44°) once every sidereal day (23h 56m 4.1s).
So the apex isn't at the pole — it sweeps around the Arctic at roughly 15° of longitude per hour, circling the globe every 23 hours and 56 minutes. The green track on the globe shows this full daily path.
For any point on Earth's surface with ECEF position vector r, its height above the ecliptic plane is the dot product of r with the ENP unit vector:
The ENP direction in the inertial frame (ICRF) is constant:
We rotate this into the Earth-fixed frame (ECEF) using CesiumJS's high-precision ICRF-to-Fixed rotation matrix, then scan every point on a grid covering 60°N–75°N to find the maximum dot product. The grid uses ETOPO 2022 topographic data at 2-arc-minute resolution (~4.86 million points), so mountains that protrude above the WGS84 ellipsoid get a real advantage.
Yes, significantly. On a perfectly smooth WGS84 ellipsoid (no mountains), the apex would always lie at exactly the sub-ENP latitude (~66.56°N) and the ecliptic height would be determined entirely by Earth's oblate shape. The equatorial bulge (semi-major axis 6,378 km) vs. the polar flattening (semi-minor axis 6,357 km) creates a strong latitude dependence.
But mountains shift the apex. A peak doesn't need to be at the exact optimal latitude — it just needs enough elevation to compensate for being slightly off. The maximum ecliptic height any surface point can achieve (over all possible times) is:
where (x, y, z) is the point's ECEF position and ε = 23.44° is the obliquity. This depends only on latitude and elevation, not longitude — every point gets its turn once per sidereal day.
The single point on Earth that gets highest above the ecliptic plane is Mont Forel (3,383 m), a nunatak in the Schweizerland Alps of East Greenland at 66.935°N, 36.786°W. It wins because of its rare combination: a tall exposed rock peak sitting almost exactly at the magic latitude of ~66.56°N.
The apex visits Mont Forel once every 23 hours 56 minutes (a sidereal day — one rotation relative to the stars). But when? Here's an elegant shortcut: the Sun is always near the horizon at the apex. This is because the ecliptic north pole direction is perpendicular to the Sun (the Sun lies in the ecliptic plane, by definition), so the point highest above that plane is always ~90° from the subsolar point — right on the day/night boundary. If you're standing at the apex, you'll see the Sun on the horizon, either rising or setting.
So to catch the apex at Mont Forel, the Sun is always near the horizon. Which side depends on the season:
This pattern isn't a coincidence. The Arctic Circle (66.56°N) and the optimal apex latitude (~66.56°N) are both set by Earth's axial tilt of 23.44° (= 90° − 66.56°). Mont Forel sits at 66.94°N, right at this boundary, so the Sun is always close to the horizon when the apex arrives — it just transitions smoothly from rising to setting and back over the course of the year. Use the Go to Max Time for This Day button to find the next occurrence.
Here's how the top candidates compare:
| Peak | Latitude | Elevation | Max ecliptic height | vs. Mont Forel |
|---|---|---|---|---|
| Mont Forel, Greenland | 66.94°N | 3,383 m | 6,363.387 km | winner |
| Gunnbjorn Fjeld, Greenland | 68.92°N | 3,694 m | 6,358.419 km | −4,968 m |
| Dome, Watkins Range | 68.90°N | 3,683 m | ~6,358.3 km | −5,100 m |
| Cone, Watkins Range | 68.88°N | 3,669 m | ~6,358.1 km | −5,300 m |
| Denali, Alaska | 63.07°N | 6,190 m | 6,354.462 km | −8,925 m |
| Hvannadalshnúkur, Iceland | 64.01°N | 2,110 m | ~6,354.2 km | −9,200 m |
| Galdhøpiggen, Norway | 61.64°N | 2,469 m | ~6,347.3 km | −16,100 m |
| Ellipsoid optimum (sea level) | 66.56°N | 0 m | 6,360.141 km | −3,246 m |
| For comparison — famous "tops of the world" that aren't: | ||||
| North Pole | 90.00°N | 0 m | 5,832 km | −531 km |
| Mt. Everest, Nepal/Tibet | 28.00°N | 8,849 m | 4,979 km | −1,384 km |
Gunnbjorn Fjeld (Greenland's highest peak at 3,694 m) is 311 m taller, but at 68.92°N it's ~2.4° too far north — you'd need an 8,228 m peak at that latitude to tie Mont Forel. The other Watkins Range peaks (Dome, Cone) are nearby but slightly lower. Denali (6,190 m) is nearly twice as tall, but at 63.07°N it's ~3.5° too far south. Hvannadalshnúkur (Iceland) and Galdhøpiggen (Norway) are in the right latitude band but too short. Notice that the bare ellipsoid at the optimal latitude still beats every peak except Mont Forel — that's how finely balanced the tradeoff between latitude and altitude is.
At 3,383 m elevation, the optimal latitude shifts only negligibly from 66.561°N. Mont Forel sits at 66.935°N — just 0.37° off the theoretical optimum. No other named peak in the world combines this much height with this much proximity to the magic latitude. It's the Goldilocks peak: tall enough to matter, and in almost exactly the right place.
Mont Forel is a nunatak — an exposed rock summit protruding through the Greenland ice sheet. It was first climbed in 1939 by the Swiss expedition of André Roch and was believed to be Greenland's highest peak until Gunnbjorn Fjeld was surveyed in 1935. It is located in the Schweizerland Alps of East Greenland, north of Ammassalik.
The semi-transparent disc on the 3D globe shows the ecliptic plane passing through Earth's center. It's tilted 23.44° from the equator and appears to rotate slowly (one full turn per sidereal day) as Earth spins. The Camera: Ecliptic mode places the camera on this plane looking at Earth edge-on, with the apex visible at the top of the silhouette.
Speed — animation multiplier (1x real-time to 3600x).
Date/Time — jump to any moment.
Camera: Ecliptic — lock camera onto the ecliptic plane (apex at top).
Camera: Follow Apex — lock camera above the apex as it sweeps around.
Go to Max Time for This Day — jump to the next moment when the
apex reaches the global maximum (Mont Forel).
Topo toggle — compare topographic vs. pure ellipsoid apex.
Topography: NOAA ETOPO 2022, 60-arc-second global relief model, extracted for 60°N–75°N and downsampled to 2-arc-minute resolution. Sharp summit elevations corrected from survey data for known peaks.
Earth orientation: CesiumJS ICRF/ITRF rotation via IAU precession/nutation models.
Ellipsoid: WGS84 (a = 6,378,137 m, f = 1/298.257).
Obliquity: J2000.0 mean value, 23.4393°.