Galactic
One galactic year ≈ 225 Myr. Sol orbits Sagittarius A* at 220 km/s from a radius of 8.122 kpc.
Top-down view of the Milky Way's 4-arm logarithmic spiral. Sol is marked at radius 0.58 of the visualization, mapped to its actual 8.122 kpc orbit. The angular position derives from the current galactic-year cycle phase.
A galactic year (≈ 225 Myr) is one full orbit of the Sun around the Milky Way's center. Earth has completed roughly 20 of these since formation 4.543 Gyr ago.
The Sun's motion through the galaxy: 220 km/s tangential orbital velocity around Sgr A*, plus a 13.4 km/s peculiar motion relative to the Local Standard of Rest, pointing toward the constellation Hercules (the Solar Apex).
The S-stars orbit Sagittarius A* at distances of a few light- days. Their orbits are tracked precisely; S2 has a 16.05-year period and provided the strongest evidence for the central supermassive black hole.
Positions are propagated live from published orbital elements (period, eccentricity, semi-major axis, time of pericenter).
A pericenter is the moment a star is closest to Sgr A* — when relativistic effects (gravitational redshift, Schwarzschild precession) are strongest and most observable. The apocenter is the farthest point. Together they form each star's core orbital cycle.
The Sun itself orbits the galactic center on an eccentric path with its own pericenter and apocenter. Best current estimates put Sol's most recent apocenter passage around ~7 Myr ago and the next pericenter in roughly ~15 Myr, with a full galactic year of ~225–250 Myr.
Because no third body is involved, this is technically a core cycle too — but the timescale is so long (and the orbital parameters poorly constrained vs. the S-stars) that we list it here as reference rather than including it in the live Galactic Calendar above.
Each star's true-anomaly in degrees is computed live from its Keplerian orbit around Sagittarius A* — the supermassive black hole at the heart of the Milky Way. 0° is pericenter (closest approach), 180° is apocenter, 360° returns to pericenter.
Why apsides? Pericenter and apocenter form a core cycle — an orbit defined purely by the star and the single mass it orbits (Sgr A*), with no dependence on any third body. This is the cleanest, most fundamental rhythm to study. Compound cycles (like a moon phase, which depends on three bodies shifting at once) are derivative; apsidal cycles are primary.
Solving Kepler's equation (M = E − e sin E) gives the exact angle within the orbit at this instant. Periods range from ~4 yr (S4716) to ~3580 yr (S85).
The Σ Sum and μ Average across every tracked star form a galactic-scale alignment signature — unique to this exact moment. This data is computed locally and cross-referenced with our internal apsis database; no public ephemeris service publishes these values live.
The compact radio source at the Milky Way's center, confirmed to be a supermassive black hole of ~4.15 million solar masses. Its event-horizon-scale image was published by the Event Horizon Telescope collaboration in 2022.
Nested timescales and spatial scales that anchor TIME CORE's galactic context — from our 4.567 Gyr solar system to the ~93 Gly observable universe.