(85) Io
ephemeris	date	magn	radius	delta	ra	dec	elong	phase
Today	18 Sep 2025	11.2	2.266 AU	1.366 AU	01h45m	+13°56'	145.4°	14.6°
Opposition	16 Oct 2025	10.4	2.313 AU	1.316 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)                : 0.1930854
            a (Semimajor axis)              : 2.6530325
            i (Inclination)                 : 11.96082
            Ω (Longitude of ascending node) : 203.04207
            ω (Argument of perihelion)      : 122.89557
            M (Mean anomaly)                : 48.27419
            Epoch                           : 2025 Nov 21

            L (Longitude of perihelion)     : 146.51370
            B (Latitude of perihelion)      : 10.02128
            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
2025-09-18 00:00 UT   01 45 28.6   +13 56 40     1.366    2.266  145.4   14.6   245   11.2 
2025-09-18 08:19 UT   01 45 20.6   +13 53 53     1.364    2.267  145.8   14.4   245   11.2 
2025-09-19 00:00 UT   01 45 05.1   +13 48 33     1.361    2.268  146.5   14.1   245   11.2 
2025-09-20 00:00 UT   01 44 40.0   +13 40 12     1.356    2.269  147.7   13.7   245   11.2 
2025-09-21 00:00 UT   01 44 13.5   +13 31 38     1.351    2.271  148.8   13.2   245   11.1 
2025-09-22 00:00 UT   01 43 45.4   +13 22 51     1.347    2.272  149.9   12.8   245   11.1 
2025-09-23 00:00 UT   01 43 16.0   +13 13 52     1.343    2.274  151.1   12.3   245   11.1 
2025-09-24 00:00 UT   01 42 45.2   +13 04 41     1.339    2.275  152.2   11.9   245   11.1 
2025-09-25 00:00 UT   01 42 13.0   +12 55 18     1.336    2.277  153.4   11.4   245   11.1 
2025-09-26 00:00 UT   01 41 39.6   +12 45 44     1.332    2.279  154.6   10.9   245   11.0 
2025-09-27 00:00 UT   01 41 04.9   +12 35 60     1.329    2.280  155.7   10.4   245   11.0 
2025-09-28 00:00 UT   01 40 29.0   +12 26 05     1.326    2.282  156.9    9.9   244   11.0 
2025-09-29 00:00 UT   01 39 52.1   +12 15 60     1.323    2.284  158.1    9.4   244   11.0 
2025-09-30 00:00 UT   01 39 14.1   +12 05 46     1.321    2.285  159.3    8.9   244   10.9 
2025-10-01 00:00 UT   01 38 35.1   +11 55 22     1.319    2.287  160.5    8.4   244   10.9 
2025-10-02 00:00 UT   01 37 55.1   +11 44 51     1.317    2.289  161.7    7.9   244   10.9 
2025-10-03 00:00 UT   01 37 14.4   +11 34 12     1.315    2.290  162.9    7.4   244   10.9 
2025-10-04 00:00 UT   01 36 32.8   +11 23 25     1.313    2.292  164.1    6.9   244   10.8 
2025-10-05 00:00 UT   01 35 50.4   +11 12 32     1.312    2.294  165.3    6.3   244   10.8 
2025-10-06 00:00 UT   01 35 07.4   +11 01 32     1.311    2.295  166.5    5.8   244   10.8 
2025-10-07 00:00 UT   01 34 23.8   +10 50 27     1.310    2.297  167.8    5.3   244   10.8 
2025-10-08 00:00 UT   01 33 39.7   +10 39 17     1.310    2.299  169.0    4.8   244   10.7 
2025-10-09 00:00 UT   01 32 55.1   +10 28 03     1.310    2.300  170.2    4.2   244   10.7 
2025-10-10 00:00 UT   01 32 10.1   +10 16 45     1.310    2.302  171.5    3.7   244   10.7 
2025-10-11 00:00 UT   01 31 24.7   +10 05 25     1.310    2.304  172.7    3.2   245   10.7 
2025-10-12 00:00 UT   01 30 39.1   +09 54 01     1.311    2.305  173.9    2.6   245   10.6 
2025-10-13 00:00 UT   01 29 53.3   +09 42 37     1.311    2.307  175.2    2.1   245   10.6 
2025-10-14 00:00 UT   01 29 07.4   +09 31 11     1.313    2.309  176.4    1.6   246   10.6 
2025-10-15 00:00 UT   01 28 21.5   +09 19 44     1.314    2.311  177.6    1.0   247   10.5 
2025-10-16 00:00 UT   01 27 35.5   +09 08 19     1.316    2.312  178.9    0.5   250   10.5 
2025-10-17 00:00 UT   01 26 49.7   +08 56 54     1.317    2.314  179.8    0.1    18   10.4 
2025-10-18 00:00 UT   01 26 04.1   +08 45 31     1.320    2.316  178.6    0.6    58   10.5 

    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.