Integrating Extended N-Body Trajectory
Loading Live Data
DOPRI5(4) :: tol 1e-9 :: 8 planets (Simon 1994) + Moon + 16 MBAs + GR + Yarkovsky
Astrophyzix Flagship Series OBS-09
PHA LIVE N-BODY FLOAT64

Live Apophis Tracker Console V5

Real-time numerical propagation of asteroid 99942 Apophis using Dormand-Prince 5(4) adaptive Runge-Kutta. Eight major planets seeded from Simon et al. (1994) A&A 282, 663 analytical elements (superseding Standish 1992; planet position error reduced from ~50,000 km to ~500 km). Separated Earth and Moon via Brown-Meeus lunar series, sixteen most-massive main-belt asteroids, Schwarzschild GR correction, and Yarkovsky thermal drag. JPL Horizons orbital solution baseline. Float64 throughout.

DOPRI5(4)
26 BODIES
SIMON 1994
FLOAT64
5.0
~500 km
UTC clock initialising...
Integrator Status
DOPRI5(4) :: 7-stage FSAL :: PI step
- steps
tol 1e-9
-
Simon et al. 1994 A&A 282, 663
Live Position (numerical integration)
HELIO DIST
-
AU
EARTH DIST
-
AU / Mkm
SPEED
-
km / s
VIS MAG
-
apparent V
RA J2000
-
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)MagRA DecElong
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.

Notable Near-Earth Asteroids
ObjectDiameterea (AU)ClassVisited by
99942 Apophis~340-450 m0.1920.923 PHA, AtenOSIRIS-APEX, Ramses
101955 Bennu490 m0.2041.126 PHA, ApolloOSIRIS-REx (sample 2023)
65803 Didymos780 m + 150 m0.3841.644 PHA, binaryDART (2022), Hera (2026)
162173 Ryugu900 m0.1901.190 Apollo, C-typeHayabusa2 (sample 2020)
433 Eros16.8 km0.2231.458 Amor, S-typeNEAR 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
  • Planet ephemeris: Simon et al. (1994) A&A 282, 663 - replaces Standish (1992)
  • Perturbers: 8 planets + Moon (separated) + Big-16 MBAs = 25 bodies
  • Planet positions: Simon 1994 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
  • Sun J2: 2.2e-7 with R_sun = 0.004652478 AU
  • SRP: 5.36e-13 AU/d^2 at 1 AU
ASTROPHYZIX :: OBS-09 DOPRI5(4) :: 26 BODIES :: SIMON 1994 :: GR + YARKO
Copyright (c) 2026 Astrophyzix.org. All rights reserved.
Redistribution not allowed. Instrument Recalibrated: June 2026
Data sources: JPL Horizons :: CNEOS :: ESA Planetary Defence