Asteroid 15 Eunomia is one of the largest asteroids in the main asteroid belt, with a diameter of about 270 kilometers. It was discovered on July 29, 1851, by the Italian astronomer Annibale de Gasparis. The asteroid was named after Eunomia, the Greek goddess of law and order. Eunomia orbits the Sun at a distance of about 2.64 astronomical units (AU), with an orbital period of about 4.38 years. Eunomia is classified as an S-type asteroid, indicating that its surface is likely composed of silicate materials. Astronomers have observed that Eunomia has a small moon, which has a diameter of about 4 kilometers and orbits at a distance of approximately 110 kilometers from the asteroid's center.
Find it in the Sky
Chose a date & time and view the position of asteroid 15 Eunomia in the sky on our interactive planetarium.
In Evidence
Asteroid 15 Eunomia
Asteroid 15 Eunomia is in the constellation of Cancer, at a distance of
Finder Charts
The sky charts below show, at different resolutions, the position of asteroid 15 Eunomia in the sky. Click on each chart to access the interactive star map tool.
The following map uses photographic imagery from the Digitized Sky Survey (DSS) to realistically visualize the precise position of asteroid 15 Eunomia against the stars in the background. The horizontal size of the map measures 60 arcminutes. Click on the image to access a more detailed full-screen view.
Equatorial Coordinates
Apparent
J2000
Additional Information
Rise and Set Times
The following table lists today's rise, transit and set times of asteroid 15 Eunomia from Greenwich, UK (all times relative to the local timezone Europe/London):
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Distance from Earth
The distance of asteroid 15 Eunomia from Earth is currently
The following graph shows the distance of asteroid 15 Eunomia from Earth as a function of time. In the chart the distance is measured in Astronomical Units and the data is sampled with an interval of 1 day.
Note: The values in this chart may not be entirely accurate around the time of closest approach for objects passing very close to Earth at high speed (e.g., Near-Earth Objects).
The value of the distance of 15 Eunomia from Earth is also available as a real time updated value in the live position tracker.
Closest Approach to Earth
In the period between January 1, 1900 and December 31, 2099, the closest approach of asteroid 15 Eunomia to Earth will happen on Saturday 24 October 2071 at a distance of 1.190320 Astronomical Units, or 178,069,374 kilometers:
Note: the values for the closest approach are computed with a sampling interval of 1 day.
Light Curve
The following chart shows the light curve of asteroid 15 Eunomia, i.e., its apparent magnitude as a function of time. The curve is calculated using the latest ephemerides provided by JPL Horizons. The magnitude data is sampled with the interval of 2 days. Because of this sampling, inaccuracies may occur for objects that have large variations of brightness over a few days. For comets, large discrepancies can arise between the calculated brightness and the observations due to their highly dynamic, and not always precisely predictable, behavior.
Orbital Elements
The following table lists the orbital elements of asteroid 15 Eunomia at epoch February, 24 2023 00:00 UTC (JD: 2460000.5). Source: JPL Small-Body Database
| Element | Symbol | Value |
|---|---|---|
| Orbit eccentricity | e | 0.18700976 |
| Orbit inclination | i | 11.75360648° |
| Perihelion distance | q | 2.14877925 AU 321,452,801 km |
| Aphelion distance | Q |
3.13733404 AU 469,338,492 km |
| Semi-major axis | a |
2.64305664 AU 395,395,647 km |
| Orbital period | period |
4.2970 years 1,569.4885 days |
| Date of perihelion transit | Tp | July 14, 2024 2,460,505.5914 JD |
| Next perihelion transit | October 30, 2028 2,462,075.0799 JD |
|
| Argument of perihelion | peri | 98.713244720149° |
| Longitude of the ascending node | node | 292.90826165525° |
| Mean anomaly | M | 244.14510652076° |
| Mean motion | n | 0.22937410°/day |
Orbit Visualization
The following chart is a 3D animated visualization of the orbit of asteroid 15 Eunomia relative to the other major objects in the Solar System. You can access more advanced features using our 3D Solar System Viewer.
Physical Properties
The table below lists the known key physical properties of asteroid 15 Eunomia. The source for this data is the JPL Small-Body Database.
| Physical Parameter | Value | Relative to Earth |
|---|---|---|
| Diameter | 255.33 km | 0.0200 |
| Sideral Rotation | 6.0830 hours | 0.2542 |
| Absolute Magnitude | 5.28 | |
| Geometric Albedo | 0.2094 |
15 Days Ephemeris
The following table lists the ephemerides of asteroid 15 Eunomia computed for the past and next 7 days, with a 24 hours interval. Apparent celestial coordinates are provided.
| Date | Right AscensionR.A. | DeclinationDec. | MagnitudeMag | Constellation |
|---|---|---|---|---|
| Jul 10 2025 | 08h 38m 49s | +14° 56’ 49” | 10.79 | Cancer |
| Jul 11 2025 | 08h 40m 27s | +14° 48’ 52” | 10.79 | Cancer |
| Jul 12 2025 | 08h 42m 05s | +14° 40’ 52” | 10.79 | Cancer |
| Jul 13 2025 | 08h 43m 43s | +14° 32’ 49” | 10.78 | Cancer |
| Jul 14 2025 | 08h 45m 21s | +14° 24’ 43” | 10.78 | Cancer |
| Jul 15 2025 | 08h 46m 58s | +14° 16’ 34” | 10.78 | Cancer |
| Jul 16 2025 | 08h 48m 36s | +14° 08’ 22” | 10.78 | Cancer |
| Jul 17 2025 | 08h 50m 12s | +14° 00’ 06” | 10.77 | Cancer |
| Jul 18 2025 | 08h 51m 49s | +13° 51’ 49” | 10.77 | Cancer |
| Jul 19 2025 | 08h 53m 26s | +13° 43’ 28” | 10.76 | Cancer |
| Jul 20 2025 | 08h 55m 03s | +13° 35’ 04” | 10.76 | Cancer |
| Jul 21 2025 | 08h 56m 40s | +13° 26’ 37” | 10.76 | Cancer |
| Jul 22 2025 | 08h 58m 16s | +13° 18’ 07” | 10.75 | Cancer |
| Jul 23 2025 | 08h 59m 53s | +13° 09’ 35” | 10.75 | Cancer |
Additional Resources on TheSkyLive
- Asteroid 15 Eunomia: Complete reference information on TheSkyLive.com.
- Where is asteroid 15 Eunomia?: Key information on where to find asteroid 15 Eunomia in the sky.
- Distance of asteroid 15 Eunomia from Earth: Find out how far asteroid 15 Eunomia is from Earth right now.
- How Bright is asteroid 15 Eunomia?: Current visual brightness (magnitude) and apparent size.
- Rise and Set Times: Rise and set times of asteroid 15 Eunomia from your location.
- Interactive Sky Map: Planetarium-style interactive visualization of asteroid 15 Eunomia's position in the sky.
- Live Position Tracker: High precision real time tracker of asteroid 15 Eunomia's position using deep space imagery.
- Ephemeris: 15 days asteroid 15 Eunomia's computed ephemeris.
- Orbital elements: Information about asteroid 15 Eunomia orbital parameters.
- Orbit Visualization: 3D interactive visualization showing the orbit of asteroid 15 Eunomia with respect to the major Solar System objects.
- Physical Data: Detailed information about physical properties of asteroid 15 Eunomia.