(85) Io
ephemeris	date	magn	radius	delta	ra	dec	elong	phase
Today	13 Aug 2025	11.9	2.215 AU	1.641 AU	01h40m	+16°12'	110.9°	25.3°
Opposition	16 Oct 2025	10.4	2.313 AU	1.317 AU	01h27m	+09°02'	179.5°	0.2°

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 Io are:

            e (Eccentricity)                : 0.1932075
            a (Semimajor axis)              : 2.6533729
            i (Inclination)                 : 11.96037
            Ω (Longitude of ascending node) : 203.04302
            ω (Argument of perihelion)      : 122.89363
            M (Mean anomaly)                : 2.65610
            Epoch                           : 2025 May 05

            L (Longitude of perihelion)     : 146.51265
            B (Latitude of perihelion)      : 10.02112
            P (Orbital period in years)     : 4.32            
        

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. A more printer-friendly version of the same chart can be found below.

Ephemerides:

Date       Time       RA (2000)    DEC (2000)    delta   radius  elong  phase   PA    magn
2025-08-13 00:00 UT   01 40 34.6   +16 12 38     1.641    2.215  110.9   25.3   247   11.9 
2025-08-13 19:44 UT   01 41 05.7   +16 12 49     1.633    2.216  111.6   25.2   247   11.9 
2025-08-14 00:00 UT   01 41 12.3   +16 12 50     1.632    2.216  111.7   25.1   247   11.9 
2025-08-15 00:00 UT   01 41 48.4   +16 12 50     1.622    2.217  112.5   25.0   247   11.9 
2025-08-16 00:00 UT   01 42 22.9   +16 12 38     1.613    2.219  113.4   24.8   247   11.9 
2025-08-17 00:00 UT   01 42 55.9   +16 12 12     1.604    2.220  114.2   24.6   247   11.8 
2025-08-18 00:00 UT   01 43 27.3   +16 11 34     1.595    2.221  115.0   24.4   247   11.8 
2025-08-19 00:00 UT   01 43 57.0   +16 10 43     1.586    2.223  115.9   24.2   247   11.8 
2025-08-20 00:00 UT   01 44 25.2   +16 09 38     1.577    2.224  116.8   24.0   246   11.8 
2025-08-21 00:00 UT   01 44 51.6   +16 08 21     1.568    2.225  117.6   23.8   246   11.8 
2025-08-22 00:00 UT   01 45 16.4   +16 06 49     1.559    2.227  118.5   23.5   246   11.8 
2025-08-23 00:00 UT   01 45 39.6   +16 05 04     1.550    2.228  119.4   23.3   246   11.7 
2025-08-24 00:00 UT   01 46 01.0   +16 03 06     1.541    2.229  120.3   23.1   246   11.7 
2025-08-25 00:00 UT   01 46 20.7   +16 00 54     1.533    2.231  121.2   22.8   246   11.7 
2025-08-26 00:00 UT   01 46 38.6   +15 58 27     1.524    2.232  122.1   22.6   246   11.7 
2025-08-27 00:00 UT   01 46 54.9   +15 55 47     1.516    2.233  123.0   22.3   246   11.7 
2025-08-28 00:00 UT   01 47 09.4   +15 52 53     1.508    2.235  123.9   22.0   246   11.6 
2025-08-29 00:00 UT   01 47 22.1   +15 49 44     1.499    2.236  124.9   21.7   246   11.6 
2025-08-30 00:00 UT   01 47 33.1   +15 46 22     1.491    2.238  125.8   21.5   246   11.6 
2025-08-31 00:00 UT   01 47 42.3   +15 42 45     1.484    2.239  126.8   21.2   246   11.6 
2025-09-01 00:00 UT   01 47 49.8   +15 38 54     1.476    2.241  127.7   20.9   246   11.6 
2025-09-02 00:00 UT   01 47 55.5   +15 34 48     1.468    2.242  128.7   20.6   246   11.5 
2025-09-03 00:00 UT   01 47 59.4   +15 30 28     1.461    2.243  129.7   20.2   246   11.5 
2025-09-04 00:00 UT   01 48 01.6   +15 25 54     1.453    2.245  130.7   19.9   246   11.5 
2025-09-05 00:00 UT   01 48 01.9   +15 21 05     1.446    2.246  131.7   19.6   246   11.5 
2025-09-06 00:00 UT   01 48 00.5   +15 16 02     1.439    2.248  132.7   19.2   246   11.5 
2025-09-07 00:00 UT   01 47 57.4   +15 10 44     1.432    2.249  133.7   18.9   246   11.4 
2025-09-08 00:00 UT   01 47 52.5   +15 05 12     1.425    2.251  134.7   18.5   246   11.4 
2025-09-09 00:00 UT   01 47 45.8   +14 59 25     1.418    2.252  135.7   18.2   245   11.4 
2025-09-10 00:00 UT   01 47 37.4   +14 53 24     1.412    2.254  136.8   17.8   245   11.4 
2025-09-11 00:00 UT   01 47 27.2   +14 47 08     1.405    2.255  137.8   17.4   245   11.4 
2025-09-12 00:00 UT   01 47 15.4   +14 40 38     1.399    2.257  138.9   17.1   245   11.3 

    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.