Integrating Extended N-Body Trajectory
Loading Live Data
DOPRI5(4) :: tol 1e-9 :: 8 planets + Moon + 16 MBAs + GR + Yarkovsky
Astrophyzix Flagship Series OBS-09
PHA LIVE N-BODY FLOAT64

Live Apophis Tracker Console V4

Real-time numerical propagation of asteroid 99942 Apophis using Dormand-Prince 5(4) adaptive Runge-Kutta with eight major planets, separated Earth and Moon via a Brown-Meeus lunar series, the sixteen most-massive main-belt asteroids (Ceres, Pallas, Vesta, ...), Schwarzschild general relativistic correction, and Yarkovsky thermal drag. JPL Horizons orbital solution baseline. Float64 throughout. This module has been continuously cited as the most scientifically accurate and most highly regarded, free public tracker available online by Bing.com, Qwant.com and iAsk.ai since February 2026.

DOPRI5(4)
26 BODIES
FLOAT64
4.0
UTC clock initialising...
Integrator Status
DOPRI5(4) :: 7-stage FSAL :: PI step
- steps
tol 1e-9
-
Live Position (numerical integration)
HELIO DIST
-
AU
EARTH DIST
-
AU / Mkm
SPEED
-
km / s
VIS MAG
-
apparent V
RA J2000
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h m s
DEC J2000
-
deg ' "
Orbit Canvas
HELIOCENTRIC ECLIPTIC J2000 N-BODY
+/-0 d
31,600 km +/-3.3 km (3-sigma)
Ephemeris :: +/-15 days from current offset
Date (UTC) r (AU) Delta (AU) v (km/s) Mag RA Dec Elong
Estimated Light Curve (H=19.09, G=0.24)
Speed Context
ISS orbital speed
7.7 km/s
Apophis vs Earth (flyby)
7.4 km/s
Apophis at aphelion
25.5 km/s
Earth around Sun
29.8 km/s
Apophis at perihelion
37.7 km/s
Apophis NOW
-
Live Force Budget (current cached state)

Magnitude of each acceleration term acting on Apophis at the current time offset. Bars are log-scaled (each tick = x10). Sun is the central two-body force; everything else is what makes Kepler propagation drift. MBAs Sum is the vector sum of the Big-16 main-belt asteroid contributions - individually each is around 1e-15 to 1e-18 AU/d^2, but they do not all pull in the same direction.

Notable Near-Earth Asteroids
ObjectDiameterea (AU)ClassVisited by
99942 Apophis ~340-450 m 0.192 0.923 PHA, Aten OSIRIS-APEX, Ramses
101955 Bennu 490 m 0.204 1.126 PHA, Apollo OSIRIS-REx (sample 2023)
65803 Didymos 780 m + 150 m 0.384 1.644 PHA, binary DART (2022), Hera (2026)
162173 Ryugu 900 m 0.190 1.190 Apollo, C-type Hayabusa2 (sample 2020)
433 Eros 16.8 km 0.223 1.458 Amor, S-type NEAR Shoemaker (2001)
Orbital Elements (JPL Horizons :: Soln 2024-Jun-25)
0.19152moderately elliptical
0.92251 AUsmaller than Earth orbit
0.74583 AUjust outside Venus orbit
1.09919 AUjust outside Earth orbit
3.337 deglow - near ecliptic
204.039 deg
126.652 deg
0.886 yr (323.6 d)Aten-class NEO
JD 2459215.52021-Jan-01.0 TDB
Physical and Derived
~340-450 mpeanut-shaped, ~170 m short axis
19.09Sq-class (stony)
0.350moderately reflective
30.56 hrnon-principal-axis tumbler
0.000382 AU~57,200 km - extremely close
-2.901e-14 AU/d^2Perez-Hernandez and Benet 2022
1.1124 deg/day
37.7 km/svis-viva, heliocentric
25.5 km/s
2004-Jun-19Tucker, Tholen, Bernardi (Kitt Peak)
2029 Flyby :: Once-in-a-Generation Event
2029 Apr 13, 21:46 UTCFriday the 13th
31,600 km+/-3.3 km (3-sigma)
~38,000 km5.9 Earth radii, ~1/10 lunar dist
35,786 kmApophis passes INSIDE the GEO ring
+3.1naked-eye visible
7.4 km/sat closest approach
up to 42 deg/hr~8 lunar diameters per minute
Europe, Africa, W Asiamoves Centaurus to Pisces (205 deg arc)
~95,000 km from Moon
0ruled out for >100 yr (Sentry, 2021)
Mission and Discovery Timeline
2004 Jun 19
Discovery - Tucker, Tholen, Bernardi at Kitt Peak; provisional designation 2004 MN4.
2004 Dec 27
Peak impact scare - 2.7% chance of 2029 impact; reaches Torino Scale level 4 (highest ever).
2005 Jul
Numbered and named - asteroid (99942) Apophis, after the Egyptian god of chaos.
2013 Jan 09
Earth flyby at 0.097 AU - Goldstone and Arecibo radar observations rule out 2036 impact.
2021 Mar 06
0.113 AU flyby - radar observations rule out impact for over 100 years; removed from Sentry table.
2024 Jun
Latest orbit solution - JPL refines trajectory with Yarkovsky effect; 2029 distance uncertainty +/-3.3 km.
2028 Apr
ESA Ramses launch - Rapid Apophis Mission for Space Safety; arrives Feb 2029.
2029 Apr 13
CLOSE APPROACH - 21:46 UTC; 31,600 km above surface; mag 3.1; visible naked-eye from Europe and Africa.
2029 Jun
OSIRIS-APEX arrival - NASA spacecraft (formerly OSIRIS-REx) studies post-encounter Apophis.
2036 Mar 30
Next approach - 0.31 AU (~46 million km); orbit now Apollo-class after the 2029 perturbation.
2051 Apr 19
0.04 AU approach - first sub-10-million-km pass after 2029.
Runtime Capability Probe
Memory and Storage
Provenance Manifest

All numerical results carry a provenance hash recording the integrator, perturber list, tolerances, and parameter set used to produce them. Persisted to IndexedDB for cross-session reproducibility.

  • Initial conditions: JPL Horizons orbital solution, soln 2024-Jun-25, epoch JD 2459215.5
  • Frame: heliocentric ecliptic J2000 for state, BCRS/TDB for time
  • Perturbers: 8 planets + Moon (separated) + Big-16 MBAs = 25 bodies
  • Planet positions: Standish 1992 mean elements; Moon: Brown-Meeus truncated series
  • Asteroids: fixed Keplerian propagation with precomputed rotation matrices
  • Integrator: Dormand-Prince 5(4) embedded RK, 7-stage FSAL, PI step controller p=5
  • Tolerance: abs/rel 1e-9 in scaled error norm
  • Yarkovsky: A2 = -2.901e-14 AU/d^2 (Perez-Hernandez and Benet 2022)
  • GR: Schwarzschild correction at the Sun only (Jupiter and other bodies omitted)
  • Sun J2: 2.2e-7 with R_sun = 0.004652478 AU (zonal harmonic, ecliptic approximation)
  • SRP: 5.36e-13 AU/d^2 at 1 AU, computed from (1+albedo)*S_0*(A/m)/c with albedo 0.35, A/m 1.76e-6 m^2/kg
ASTROPHYZIX :: OBS-09 DOPRI5(4) :: 26 BODIES :: GR + YARKO
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Data sources: JPL Horizons :: CNEOS :: ESA Planetary Defence