Live Asteroid Apophis (99942)
2029 Flyby Tracker by Astrophyzix Digital Observatory
2004 MN4 | JPL Horizons orbital solution (#2024-Jun-25) | Keplerian elliptical propagation | Potentially Hazardous Asteroid
| Parameter | Value |
|---|---|
| Eccentricity (e) | 0.19152 moderately elliptical |
| Semi-major axis (a) | 0.92251 AU smaller than Earth's orbit |
| Perihelion dist. (q) | 0.74583 AU just outside Venus's orbit |
| Aphelion dist. (Q) | 1.09919 AU just outside Earth's orbit |
| Inclination (i) | 3.337° low - near-ecliptic |
| Asc. node (Omega) | 204.039° |
| Arg. perihelion (omega) | 126.652° |
| Orbital period (P) | 0.886 yr (323.6 d) Aten-class NEO |
| Epoch | JD 2459215.5 2021-Jan-01.0 TDB |
| Physical / Derived | Value |
|---|---|
| Diameter | ~340-450 m peanut-shaped, ~170 m short axis |
| Absolute magnitude (H) | 19.09 Sq-class (stony) |
| Albedo | 0.350 moderately reflective |
| Rotation period | 30.56 hr non-principal-axis tumbler |
| Earth MOID | 0.000382 AU ~57,200 km - extremely close |
| Mean motion (n) | 1.1124°/day |
| Speed at perihelion | ~37.7 km/s vis-viva, heliocentric |
| Speed at aphelion | ~25.5 km/s |
| Discovery | 2004-Jun-19 Tucker, Tholen, Bernardi (Kitt Peak) |
| Object | Diameter | e | a (AU) | Class | Visited by |
|---|---|---|---|---|---|
| 99942 Apophis * | ~340-450 m | 0.192 | 0.923 | PHA, Aten | OSIRIS-APEX (2029), Ramses (ESA, 2029) |
| 101955 Bennu | 490 m | 0.204 | 1.126 | PHA, Apollo | OSIRIS-REx (sample returned 2023) |
| 65803 Didymos | 780 m + 150 m moon | 0.384 | 1.644 | PHA, Apollo, binary | DART (impacted Dimorphos 2022), Hera (2026) |
| 162173 Ryugu | 900 m | 0.190 | 1.190 | Apollo, C-type | Hayabusa2 (sample returned 2020) |
| 433 Eros | 16.8 km | 0.223 | 1.458 | Amor, S-type | NEAR Shoemaker (landed 2001) |
| Closest approach time | 2029 Apr 13, 21:46 UTC Friday the 13th |
| Closest distance (surface) | 31,600 km +/-3.3 km (3-sigma) |
| Closest distance (Earth center) | ~38,000 km 5.9 Earth radii, ~1/10 lunar distance |
| Geosynchronous belt altitude | 35,786 km Apophis passes INSIDE the GEO ring |
| Peak apparent magnitude | +3.1 naked-eye visible (~Big Dipper stars) |
| Earth-relative speed | 7.4 km/s at closest approach |
| Angular speed | up to 42° / hour ~8 lunar diameters per minute |
| Visible from | Europe, Africa, W. Asia moves Centaurus → Perseus → Pisces (205° arc) |
| Lunar pass (16h later) | ~95,000 km from Moon's surface |
| Impact probability | 0 ruled out for >100 years (Sentry, 2021) |
| Date (UTC) | r (AU) | Delta Earth (AU) | Speed (km/s) | Mag (est.) | RA (h m s) | Dec (deg ' ") | Elong. |
|---|
How position is computed in this tracker
> Standard Kepler equation: M = E - e*sin(E) solved via Newton-Raphson (5-8 iterations for e=0.19)
> True anomaly: tan(nu/2) = sqrt((1+e)/(1-e)) * tan(E/2)
> Heliocentric radius: r = a*(1 - e*cos(E))
> Heliocentric speed (vis-viva): v = k * sqrt(2/r - 1/a) where k = 0.01720209895 AU^(3/2)/day
> Ecliptic X,Y,Z from nu via Euler rotation: Omega, i, omega (J2000.0 ecliptic)
> Earth position from VSOP87 low-precision L,B,R series (~1 arcmin)
> RA/Dec via ecliptic->equatorial rotation (eps = 23.4393 deg)
> Magnitude: V = H + 5*log10(r*Delta) - 2.5*log10((1-G)*Phi1 + G*Phi2) using H-G phase function
! Caveat: This tracker uses pure 2-body Keplerian propagation from JPL osculating elements at epoch 2021-Jan-01. Today's distance matches published values to within ~1%. However, long term it will NOT propagate accurately. Astrophyzix updates this module regularly to keep the governing mathematical equations correct for current live data. This issue will be remedied when the module is updated to include a full N-body numerical integrator with planetary perturbations, Yarkovsky drift, and GR correction. These updates are due on 9 May 2026. For mission-grade trajectories, query JPL Horizons directly. After 2029, Apophis's orbit permanently shifts (Aten -> Apollo class, a: 0.92 -> 1.10 AU).