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Asteroid Near-Earth

1998 SD9

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(1998 SD9)

Where is it now

Distance from Sun
0.709 AU
True anomaly
121.15°
Distance from Earth
1.2 AU
As of
15 October 2026

Two-body Kepler propagation — accurate to ~0.1% for major planets over decades, less so for highly-perturbed bodies. Use JPL Horizons for high precision.

Sun Earth — 0.997 AU from the Sun Earth 1998 SD9 — 0.709 AU from the Sun 1998 SD9
Seen from above the ecliptic, north up, to scale. Grid: Earth's orbit in blue. 1998 SD9 is 1.2 AU from Earth today (10.0 light-minutes).

In the sky

Right ascension
15h 51m 24s
Declination
-18° 45′ 33″
Constellation
Libra
Distance from Earth
1.2 AU
Elongation from the Sun
36.59° — near the Sun — look low at dusk or dawn

Favours the southern hemisphere; low or below the horizon from far north.

From your location

See how high it is right now, whether it is up after civil twilight, and when it rises and sets where you are.

How do I find my coordinates?

Google Maps on a computer

  1. Right-click the spot where you'll be observing.
  2. The first line of the menu is the coordinates, e.g. 51.50722, -0.12758 — click it and they're copied.
  3. Paste them above.

Google Maps on a phone

  1. Press and hold the spot to drop a pin.
  2. The coordinates appear in the search bar (or on the pin's card) — tap to copy, then paste above.

A full Google Maps link works too, but the short maps.app.goo.gl share links don't carry coordinates — copy the numbers instead. We round to about a kilometre; that's all the sky calculation needs.

Know your what3words address? Paste it, e.g. ///filled.count.soap. This is optional — the three words are sent to what3words to convert them, and we don't store the address or the result.

Your location stays in your browser and is sent only for this calculation. Using a what3words address is optional; if you do, the three words go to what3words to be converted and we don't record them. Set a location first, then you can save an email alert for this object. See our privacy policy.

Two-body approximation, good to about a degree for the planets — enough to find the constellation and know whether it is up.

Orbital elements

Semi-major axis
0.702 AU
Eccentricity
0.5044
Inclination
2.99°
Orbital period
215.1 days
Perihelion
0.348 AU
Aphelion
1.057 AU
Longitude of ascending node
165.74°
Argument of periapsis
7.7°
Epoch · J2000
2461200.5
Orbit class · ATE
Aten
Earth MOID · 3.4 LD
0.0087 AU
Tisserand (Jupiter)
8.041

Orbit quality

Orbit very well determined (uncertainty code 0).

Observations used
150
Data arc
19.99 years
First observed
18 September 1998
Last observed
15 September 2018
Residual RMS
0.43 ″
Solution · Otto Matic
20 December 2022

Visual & observation

Absolute magnitude (H)
24.09

Discovery & classification

Aten Near-Earth Object

Close approaches 394 on record

Flyby geometry
Ecliptic flyby of 1998 SD9 at 2028-08-25 23:42 UTC Top-down view of the ecliptic, Earth at the centre, for the 2028-08-25 23:42 UTC close approach of 1998 SD9. Catalogue miss distance 23.4 LD · 8.99 × 10⁶ km. The curve is the geocentric path from 2028-08-22 to 2028-08-28, with a mark at UTC midnights and an arrow for the direction of motion. The circle is the Moon’s mean orbit; the Moon is plotted at closest approach. A ray shows the Sun’s direction. The labelled distance is the full separation. The drawn radius is the part that lies in the ecliptic plane. The path is a geocentric ecliptic ephemeris from JPL Horizons. The inset is a heliocentric view and is approximate. Sun 23.4 LD · 8.99 × 10⁶ km 2028-08-25 23:42 UTC Earth Moon Heliocentric, approximate

Top-down view of the ecliptic, Earth at the centre, for the 2028-08-25 23:42 UTC close approach of 1998 SD9. Catalogue miss distance 23.4 LD · 8.99 × 10⁶ km. The curve is the geocentric path from 2028-08-22 to 2028-08-28, with a mark at UTC midnights and an arrow for the direction of motion. The circle is the Moon’s mean orbit; the Moon is plotted at closest approach. A ray shows the Sun’s direction. The labelled distance is the full separation. The drawn radius is the part that lies in the ecliptic plane. The path is a geocentric ecliptic ephemeris from JPL Horizons. The inset is a heliocentric view and is approximate.

JPL Horizons

When (UTC) Body Distance Lunar distances Relative speed
2026-09-22 02:41:00 Merc 0.0408 AU 15.9 LD 20.1 km/s
2026-09-22 02:41:00 Mercury 0.0408 AU 15.9 LD 20.1 km/s
2027-11-08 18:07:00 Merc 0.0736 AU 28.7 LD 26.7 km/s
2027-11-08 18:07:00 Mercury 0.0736 AU 28.7 LD 26.7 km/s
2028-08-25 23:42:00 Earth 0.0601 AU 23.4 LD 12.5 km/s
2028-12-13 15:39:00 Earth 0.453 AU 176.3 LD 8.6 km/s
2029-09-24 12:09:00 Venus 0.087 AU 33.9 LD 21.2 km/s
2030-05-04 19:00:00 Venus 0.129 AU 50.2 LD 12.9 km/s
2031-10-01 17:48:00 Earth 0.0334 AU 13.0 LD 9.8 km/s
2032-01-10 20:42:00 Mercury 0.0432 AU 16.8 LD 21.4 km/s

Next ten from today. 1 lunar distance = 384,400 km. Source: JPL close-approach data.

Sources