(221) Eos
ephemeris	date	magn	radius	delta	ra	dec	elong	phase
Today	9 Dec 2025	13.3	2.711 AU	3.214 AU	20h43m	-18°40'	51.4°	16.5°
Opposition	31 Oct 2026	11.8	2.855 AU	1.888 AU	02h43m	-01°07'	163.9°	5.5°

The interactive orbit chart above shows the body's path through the solar system and its position at the given date. Green and blue lines are shown perpendicular to the ecliptic plane: Green if the path is above the ecliptic plane, blue if it is below. (Left-click and drag to rotate the view; Right-click and drag to move the view; Use scroll wheel to zoom in our out.)

The orbital elements of Eos are:

            e (Eccentricity)                : 0.1010595
            a (Semimajor axis)              : 3.0125182
            i (Inclination)                 : 10.89026
            Ω (Longitude of ascending node) : 141.71015
            ω (Argument of perihelion)      : 192.48158
            M (Mean anomaly)                : 348.95146
            Epoch                           : 2025 Nov 21

            L (Longitude of perihelion)     : 153.97381
            B (Latitude of perihelion)      : -2.34017
            P (Orbital period in years)     : 5.23            
        

The light curve chart below shows the estimated development of the minor planet's magnitude.

The all-sky chart below shows the path of the minor planet over the same period as the light curve. The current position is marked yellow.

The following chart shows the path of the minor planet in the next few days. The field of view is optimized for (~10x50) binoculars and finderscopes.

Ephemerides:

Date       Time       RA (2000)    DEC (2000)    delta   radius  elong  phase   PA    magn
2025-12-09 00:00 UT   20 43 04.6   -18 40 53     3.214    2.711   51.4   16.5    75   13.3 
2025-12-09 03:45 UT   20 43 19.4   -18 40 17     3.216    2.711   51.3   16.5    75   13.3 
2025-12-10 00:00 UT   20 44 39.7   -18 36 59     3.224    2.711   50.8   16.3    75   13.3 
2025-12-11 00:00 UT   20 46 15.1   -18 32 59     3.235    2.711   50.2   16.2    75   13.3 
2025-12-12 00:00 UT   20 47 50.8   -18 28 55     3.245    2.711   49.5   16.0    75   13.3 
2025-12-13 00:00 UT   20 49 26.8   -18 24 45     3.255    2.711   48.9   15.9    75   13.3 
2025-12-14 00:00 UT   20 51 03.1   -18 20 31     3.265    2.711   48.3   15.7    75   13.3 
2025-12-15 00:00 UT   20 52 39.7   -18 16 11     3.275    2.711   47.6   15.6    75   13.3 
2025-12-16 00:00 UT   20 54 16.5   -18 11 46     3.284    2.710   47.0   15.4    75   13.3 
2025-12-17 00:00 UT   20 55 53.6   -18 07 16     3.294    2.710   46.4   15.2    75   13.3 
2025-12-18 00:00 UT   20 57 30.9   -18 02 42     3.304    2.710   45.7   15.1    75   13.3 
2025-12-19 00:00 UT   20 59 08.4   -17 58 02     3.313    2.710   45.1   14.9    75   13.3 
2025-12-20 00:00 UT   21 00 46.2   -17 53 17     3.322    2.710   44.5   14.7    74   13.3 
2025-12-21 00:00 UT   21 02 24.2   -17 48 28     3.332    2.710   43.9   14.6    74   13.3 
2025-12-22 00:00 UT   21 04 02.4   -17 43 34     3.341    2.710   43.3   14.4    74   13.3 
2025-12-23 00:00 UT   21 05 40.8   -17 38 35     3.350    2.710   42.6   14.2    74   13.3 
2025-12-24 00:00 UT   21 07 19.4   -17 33 31     3.359    2.709   42.0   14.1    74   13.3 
2025-12-25 00:00 UT   21 08 58.2   -17 28 23     3.368    2.709   41.4   13.9    74   13.3 
2025-12-26 00:00 UT   21 10 37.2   -17 23 10     3.377    2.709   40.8   13.7    74   13.3 
2025-12-27 00:00 UT   21 12 16.4   -17 17 52     3.385    2.709   40.2   13.5    74   13.3 
2025-12-28 00:00 UT   21 13 55.7   -17 12 30     3.394    2.709   39.6   13.4    74   13.3 
2025-12-29 00:00 UT   21 15 35.2   -17 07 03     3.402    2.709   38.9   13.2    74   13.3 
2025-12-30 00:00 UT   21 17 14.8   -17 01 32     3.411    2.709   38.3   13.0    74   13.3 

    Terminology:
            
    delta:  distance between minor planet and earth in AU
    radius: distance between minor planet and sun in AU
    magn:   magnitude (brightness) estimate    
    ra:     right ascension in hours (24h = 360deg)
    dec:    declination in degrees
    elong:  elongation in degrees (angle sun-earth-minor planet)    
    phase:  phase angle in degrees (angle sun-minor planet-earth)        
    AU:     Astronomical Unit (mean distance between earth and sun: 149597870.7 km
    

Orbital elements provided by the MPC (Minor Planet Center).
Calculations by a modified version of AAPlus, a C# implementation of the AA+ project by PJ Naughter from the algorithms presented in the book "Astronomical Algorithms" by Jean Meeus.
NGC2000 dso catalog and star labels from VizieR as provided by the Strasbourg astronomical Data Center.
Tycho2 catalog from the ESO archive.