Asteroid 2026 SA8 · Astrophyzix Scientific Close-Approach & Orbital Report
Top-down schematic. Orbit size and shape are drawn from the published elements (a, e, q, Q); the orientation of the orbit and the marked encounter point are approximate. 2026 SA8's orbit is nearly the same size as Earth's — an Apollo that happens to cross very close to home.
Key Takeaways of Asteroid 2026 SA8
- Close approach: predicted for 28 Sep 2026 at 06:45 TDB (timing uncertainty ± 22 minutes), confirmed in the JPL CAD record. The miss distance is 0.988 LD (≈ 379,868 km, 0.00254 au) — slightly closer than the Moon's own average distance from Earth (384,400 km), though still roughly 60 Earth radii out.
- Speed: 6.61 km/s relative to Earth (≈ 23,800 km/h), the slowest of the recent tracked passes; v∞ 6.45 km/s.
- Orbit class: Apollo NEO — a = 1.07 au, e = 0.231, i = 1.89°, orbital period ≈ 401 days (1.10 years). Its orbit is close in size to Earth's own, only about 10% longer in period.
- Earth MOID: 0.0027 au (≈ 404,000 km). This pass, at 0.00254 au, is actually a touch closer than the nominal MOID figure — with only a 2-day arc, both numbers carry some uncertainty.
- Size estimate: absolute magnitude H = 28.634, giving a diameter of about 6.7 m (range 5.0–11.1 m, albedo-dependent) — the smallest of the recent tracked objects. The size is H-derived, not measured.
- Orbit quality: the solution rests on a very short 2-day data arc with just 11 observations, so the orbital elements are provisional and should be treated as preliminary.
- Risk context: not a Potentially Hazardous Asteroid (H is far above the H ≤ 22 PHA threshold), not on the Sentry watchlist, and no Scout entry.
- Keep it in proportion: a sub-lunar-distance flyby from a ~7 m object is a routine, expected detection for current sky surveys — small objects like this pass this close to Earth regularly and burn up harmlessly if they ever did enter the atmosphere.
Approach Scale
2026 SA8's flyby distance sits almost exactly at the Moon's own distance — the marker and the Moon's tick nearly overlap on this scale.
Scientific Consensus Snapshot of 2026 SA8
Parameter Status Orbit class Apollo NEO (a > 1 au, q < 1.017 au — Earth-crossing) Semi-major axis (a) 1.07 au Eccentricity (e) 0.231 Perihelion distance (q) 0.818 au Aphelion distance (Q) 1.31 au Inclination (i) 1.89° Orbital period ≈ 401 days (1.10 years) Earth MOID 0.0027 au (≈ 404,000 km) Tisserand parameter (TJ) ≈ 5.8 † — well above 3, firmly asteroidal Absolute magnitude (H) 28.634 (very small object) Estimated diameter ≈ 6.7 m (5.0–11.1 m), H-derived Observations / data arc 11 observations over 2 days Sentry / Scout Not on Sentry watchlist · no Scout entry Hazard level Non-hazardous size; not PHA-class
| Parameter | Status |
|---|---|
| Orbit class | Apollo NEO (a > 1 au, q < 1.017 au — Earth-crossing) |
| Semi-major axis (a) | 1.07 au |
| Eccentricity (e) | 0.231 |
| Perihelion distance (q) | 0.818 au |
| Aphelion distance (Q) | 1.31 au |
| Inclination (i) | 1.89° |
| Orbital period | ≈ 401 days (1.10 years) |
| Earth MOID | 0.0027 au (≈ 404,000 km) |
| Tisserand parameter (TJ) | ≈ 5.8 † — well above 3, firmly asteroidal |
| Absolute magnitude (H) | 28.634 (very small object) |
| Estimated diameter | ≈ 6.7 m (5.0–11.1 m), H-derived |
| Observations / data arc | 11 observations over 2 days |
| Sentry / Scout | Not on Sentry watchlist · no Scout entry |
| Hazard level | Non-hazardous size; not PHA-class |
† Derived by Astrophyzix from a, e and i. All other values are taken from the JPL CAD/SBDB record.
2026 SA8 Close-Approach Overview
Date/Time (TDB) Body Nominal distance Min–Max distance (au) Vrel (km/s) 2026-09-28 06:45 ± 00:22 Earth 0.00254 au
0.988 LD 0.00251 – 0.00257 6.61
| Date/Time (TDB) | Body | Nominal distance | Min–Max distance (au) | Vrel (km/s) |
|---|---|---|---|---|
| 2026-09-28 06:45 ± 00:22 | Earth | 0.00254 au 0.988 LD | 0.00251 – 0.00257 | 6.61 |
Same-day company
Another small object passed later the same day (28 Sep 2026):
| Object | Date/Time (TDB) | Miss distance | Velocity | Est. size | ARI |
|---|---|---|---|---|---|
| 2026 SX2 | 2026-09-28 18:11 | 4.102 LD | 7.69 km/s | 13 m | 32 |
1. Asteroid 2026 SA8
Small Apollo NEO on an orbit close in size to Earth's own, with a sub-lunar-distance flyby predicted for 28 September 2026 — dynamically notable for how close it comes, but non-hazardous in current solutions.
Small Apollo NEO on an orbit close in size to Earth's own, with a sub-lunar-distance flyby predicted for 28 September 2026 — dynamically notable for how close it comes, but non-hazardous in current solutions.
Asteroid 2026 SA8 Orbital Geometry
Parameter Value Orbit class Apollo (APO) — Earth-crossing NEO Semi-major axis (a) 1.07 au Eccentricity (e) 0.231 Perihelion distance (q) 0.818 au Aphelion distance (Q) 1.31 au Inclination (i) 1.89° Mean motion (n) ≈ 0.90 deg/day † Orbital period ≈ 401 days (1.10 years) Earth MOID 0.0027 au (≈ 404,000 km) Data arc 2 days Observations used 11
| Parameter | Value |
|---|---|
| Orbit class | Apollo (APO) — Earth-crossing NEO |
| Semi-major axis (a) | 1.07 au |
| Eccentricity (e) | 0.231 |
| Perihelion distance (q) | 0.818 au |
| Aphelion distance (Q) | 1.31 au |
| Inclination (i) | 1.89° |
| Mean motion (n) | ≈ 0.90 deg/day † |
| Orbital period | ≈ 401 days (1.10 years) |
| Earth MOID | 0.0027 au (≈ 404,000 km) |
| Data arc | 2 days |
| Observations used | 11 |
Physical Characteristics of NEO 2026 SA8
Parameter Value Absolute magnitude (H) 28.634 Estimated diameter ≈ 5.0–11.1 m (nominal 6.7 m, assuming albedo 0.25–0.05) Size source H-derived (no radar or thermal measurement) Rotation period Not published Spectral type Unknown (no published taxonomy) PHA classification No — below PHA-class threshold (derived)
2026 SA8 occupies an orbit that is, in size, almost a twin of Earth's — a = 1.07 au against Earth's 1.00 au, and a period of 401 days against Earth's 365. What makes it Earth-crossing rather than co-orbital is its eccentricity of 0.231, which carries it from 0.818 au at perihelion (between Venus and Earth) out to 1.31 au at aphelion (between Earth and Mars). At only about 5–11 m across, it is smaller than the 2013 Chelyabinsk impactor and would pose no meaningful hazard even in a hypothetical atmospheric entry.
| Parameter | Value |
|---|---|
| Absolute magnitude (H) | 28.634 |
| Estimated diameter | ≈ 5.0–11.1 m (nominal 6.7 m, assuming albedo 0.25–0.05) |
| Size source | H-derived (no radar or thermal measurement) |
| Rotation period | Not published |
| Spectral type | Unknown (no published taxonomy) |
| PHA classification | No — below PHA-class threshold (derived) |
2026 SA8 occupies an orbit that is, in size, almost a twin of Earth's — a = 1.07 au against Earth's 1.00 au, and a period of 401 days against Earth's 365. What makes it Earth-crossing rather than co-orbital is its eccentricity of 0.231, which carries it from 0.818 au at perihelion (between Venus and Earth) out to 1.31 au at aphelion (between Earth and Mars). At only about 5–11 m across, it is smaller than the 2013 Chelyabinsk impactor and would pose no meaningful hazard even in a hypothetical atmospheric entry.
Interpretation of the Predicted Approach
With just a 2-day arc and 11 observations, this is the most provisional of the recent orbit solutions in this series — the ± 22 minute timing uncertainty on the approach itself reflects that. Both the approach distance and the quoted Earth MOID should be read as preliminary until more astrometry comes in.
The passage at 0.988 LD is closer than the Moon's own orbit, which is a useful reminder of scale: even "close by astronomical standards" here means a clean miss tens of thousands of kilometres beyond any risk to Earth.
Astrophyzix Assessment:
The predicted 28 September 2026 approach is safe and non-hazardous. Its short data arc makes it a priority target for follow-up astrometry in the days around closest approach, both to firm up this pass and to characterise the orbit for future apparitions.
Astrophyzix Risk Index (ARI)
43 / 100 for 2026 SA8, matching 2026 SY2's score despite being far smaller and slower — driven mainly by its very tight approach distance.
ARI is an Astrophyzix composite index used to rank close approaches at a glance. It is not an official NASA, ESA or IAU hazard rating; the authoritative impact-risk sources are Sentry and Scout.
43 / 100 for 2026 SA8, matching 2026 SY2's score despite being far smaller and slower — driven mainly by its very tight approach distance.
ARI is an Astrophyzix composite index used to rank close approaches at a glance. It is not an official NASA, ESA or IAU hazard rating; the authoritative impact-risk sources are Sentry and Scout.