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Orbital Mechanics: Perigee vs. ApogeePerigee/Apogee

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Live Orbit Telemetry

PERIGEE PHASE

Earth-Moon Distance: 363,300 km

Perigee (363,300 km) Apogee (405,500 km)

Orbital Velocity (Kepler v): 1.082 km/s

Kepler Factor: 1.25x Peak

Gravitational Tidal Bulge: MAXIMUM

Tidal forces scale as 1/r³. At Perigee, tidal pulling power is ~30-40% greater than at Apogee, driving King Tides.

Speed: 1.0x

Ellipticity: High

Tidal Bulge Orbit Path

✦ Lunar Dynamics & Tides

1. What is Perigee and Apogee?

The Moon does not orbit Earth in a circle. It travels along an elliptical orbit where Earth sits at one of the two geometric focal points (Foci).

PERIGEE Closest lunar approach to Earth (~363,300 km). Moon appears ~14% larger.

APOGEE Farthest distance (~405,500 km). Moon appears smaller (Micromoon).

2. Kepler's Second Law

"A line segment joining a planet and the Sun sweeps out equal areas during equal intervals of time."

Notice how the Moon in this 3D graphic accelerates as it plunges towards perigee, and decelerates as it climbs out towards apogee.

3. How Perigee Triggers King Tides

Tidal gravitational gradient scales inversely with the cube of the distance (1 / r³). A small decrease in distance yields a big increase in ocean deformation.

Perigean Spring Tide ("King Tide"):

When the Moon is at Perigee and aligned with the Sun (New or Full Moon), both forces combine to create the highest coastal water levels of the year.

Tip: Click and drag to orbit around in 3D. Scroll to zoom in/out. Right-click drag to pan.