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Asteroid Near-Earth Potentially hazardous

403775

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403775 (2011 HS4)

Where is it now

Distance from Sun
1.373 AU
True anomaly
158.46°
Distance from Earth
2.327 AU
As of
22 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 — 0.995 AU from the Sun Earth 403775 — 1.373 AU from the Sun 403775
Seen from above the ecliptic, north up, to scale. Grid: Earth's orbit in blue. 403775 is 2.327 AU from Earth today (19.4 light-minutes).

In the sky

Right ascension
14h 40m 09s
Declination
-12° 27′ 58″
Constellation
Libra
Distance from Earth
2.33 AU
Elongation from the Sun
12.5° — too close to the Sun to observe

Visible from both hemispheres.

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
0.938 AU
Eccentricity
0.68
Inclination
5.46°
Orbital period
332 days
Perihelion
0.3 AU
Aphelion
1.576 AU
Longitude of ascending node
117.48°
Argument of periapsis
314.29°
Epoch · J2000
2461200.5
Orbit class · ATE
Aten
Earth MOID · 2.3 LD
0.0059 AU
Tisserand (Jupiter)
6.165

Orbit quality

Orbit very well determined (uncertainty code 0).

Observations used
135
Data arc
22.01 years
First observed
1 June 2002
Last observed
5 June 2024
Residual RMS
0.52 ″
Solution · Otto Matic
6 June 2024

Visual & observation

Absolute magnitude (H)
20.9

Discovery & classification

Discovered by
Mt. Lemmon Survey
Discovery date
26 April 2011
Discovery site
Mount Lemmon

Also known as 2011 HS4

Aten Near-Earth Object Potentially Hazardous Asteroid

Close approaches 222 on record

Flyby geometry
Ecliptic flyby of 403775 at 2030-04-23 23:12 UTC Top-down view of the ecliptic, Earth at the centre, for the 2030-04-23 23:12 UTC close approach of 403775. Catalogue miss distance 67.5 LD · 2.59 × 10⁷ km. The curve is the geocentric path from 2030-04-20 to 2030-04-26, 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. At closest approach the object is north of the ecliptic. The path is a geocentric ecliptic ephemeris from JPL Horizons. The inset is a heliocentric view and is approximate. Sun 67.5 LD · 2.59 × 10⁷ km 2030-04-23 23:12 UTC Earth Moon Heliocentric, approximate

Top-down view of the ecliptic, Earth at the centre, for the 2030-04-23 23:12 UTC close approach of 403775. Catalogue miss distance 67.5 LD · 2.59 × 10⁷ km. The curve is the geocentric path from 2030-04-20 to 2030-04-26, 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. At closest approach the object is north of the ecliptic. 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
2029-04-14 06:48:00 Mercury 0.048 AU 18.7 LD 18 km/s
2029-04-14 06:48:00 Merc 0.048 AU 18.7 LD 18 km/s
2030-04-23 23:12:00 Earth 0.1734 AU 67.5 LD 25.3 km/s
2030-12-31 02:11:00 Venus 0.1019 AU 39.7 LD 21.4 km/s
2031-04-26 01:55:00 Earth 0.356 AU 138.5 LD 14.6 km/s
2032-10-28 05:10:00 Venus 0.0944 AU 36.8 LD 30.7 km/s
2034-07-18 15:27:00 Earth 0.2036 AU 79.2 LD 15.9 km/s
2035-05-03 06:55:00 Mars 0.0971 AU 37.8 LD 12.2 km/s
2035-07-05 16:08:00 Earth 0.3028 AU 117.8 LD 30.4 km/s
2037-06-10 04:42:00 Merc 0.0273 AU 10.6 LD 12.8 km/s

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

Sources