The Molniya Orbit
A Molniya orbit is one of the most elegant solutions in spaceflight: a steep, highly elliptical 12-hour orbit that leaves a satellite loitering over the far north for most of its circuit. AstroSat renders these orbits live, and their shape is unmistakable on the globe.
The numbers right now
As of August 3, 2026, AstroSat is tracking 34 satellites in this constellation — about 0.2% of every active satellite currently tracked, out of 18,436 active satellites in total.
This is a live catalogue count, not a fixed design figure: it includes retired and spare satellites that are still in orbit and still being tracked, which is why it can differ from the “official” constellation size. Refreshed automatically from Space-Track every two hours.
Why the orbit is shaped like that
Geostationary fails up north
A geostationary satellite sits over the equator, so from high latitudes it appears low on the horizon — or below it entirely. For a country as far north as Russia, that is a genuine problem.
Slow at the top, fast at the bottom
The orbit runs from a perigee of roughly 500 km to an apogee near 40,000 km. A satellite moves slowly at apogee, so it spends around eight of its twelve hours over the northern hemisphere and races through the southern half.
The 63.4° magic number
At an inclination of 63.4° the orbit's apogee stops drifting. At any other angle Earth's equatorial bulge would slowly rotate the ellipse and the satellite would stop loitering where it is needed.
Three satellites, full cover
With a 12-hour period, three satellites spaced evenly can hand over between them so one is always high in the northern sky.
Molniya means "lightning" in Russian, and the orbit takes its name from the communications satellites first flown in it in the 1960s. The design solves a real constraint: geostationary orbit is superb for the tropics and mid-latitudes and increasingly useless as you go north, and much of Russia is very far north. The same logic drives the Tundra orbit, a 24-hour variant used by Sirius satellite radio for the same reason at North American latitudes. The 63.4° inclination is not a design preference but a consequence of orbital mechanics — the one inclination at which Earth's oblateness stops rotating the ellipse. It is also why a Molniya satellite is a useful thing to watch on a live globe: the orbit track is dramatically asymmetric in a way a circular orbit never is, and the satellite visibly crawls at the top of its arc and dives through the bottom.
Frequently asked questions
What is a Molniya orbit?
A highly elliptical orbit with a period of about 12 hours, inclined 63.4°, with apogee near 40,000 km over the northern hemisphere and perigee around 500 km. It keeps a satellite high over high latitudes for most of each orbit.
Why 63.4 degrees?
It is the critical inclination at which Earth's equatorial bulge stops rotating the orbit's apogee. At any other inclination the high point would drift away from the region the satellite is meant to serve.
Why not just use geostationary orbit?
A geostationary satellite sits above the equator, so from far northern latitudes it appears very low on the horizon or not at all. A Molniya orbit puts the satellite high overhead where geostationary cannot reach.
Are Molniya satellites still in use?
The original Molniya communications series has largely been retired, but the orbit itself is still used — including by Russian early-warning satellites — and many older Molniya-orbit objects remain tracked.