(85) Io
ephemeris	date	magn	radius	delta	ra	dec	elong	phase
Today	10 Oct 2025	10.7	2.302 AU	1.310 AU	01h32m	+10°16'	171.5°	3.7°
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
2025-10-10 00:00 UT   01 32 10.1   +10 16 45     1.310    2.302  171.5    3.7   244   10.7 
2025-10-10 04:48 UT   01 32 01.0   +10 14 30     1.310    2.302  171.7    3.6   245   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 
2025-10-19 00:00 UT   01 25 18.7   +08 34 11     1.322    2.318  177.4    1.1    60   10.5 
2025-10-20 00:00 UT   01 24 33.7   +08 22 54     1.325    2.319  176.1    1.7    61   10.6 
2025-10-21 00:00 UT   01 23 49.0   +08 11 41     1.328    2.321  174.9    2.2    62   10.6 
2025-10-22 00:00 UT   01 23 04.8   +08 00 33     1.331    2.323  173.7    2.7    62   10.7 
2025-10-23 00:00 UT   01 22 21.2   +07 49 30     1.335    2.325  172.4    3.2    62   10.7 
2025-10-24 00:00 UT   01 21 38.2   +07 38 33     1.339    2.327  171.2    3.8    62   10.8 
2025-10-25 00:00 UT   01 20 55.9   +07 27 43     1.343    2.328  170.0    4.3    63   10.8 
2025-10-26 00:00 UT   01 20 14.3   +07 16 60     1.347    2.330  168.7    4.8    63   10.8 
2025-10-27 00:00 UT   01 19 33.6   +07 06 25     1.352    2.332  167.5    5.3    63   10.9 
2025-10-28 00:00 UT   01 18 53.7   +06 55 58     1.356    2.334  166.3    5.8    63   10.9 
2025-10-29 00:00 UT   01 18 14.7   +06 45 41     1.362    2.336  165.1    6.3    63   10.9 
2025-10-30 00:00 UT   01 17 36.7   +06 35 33     1.367    2.337  163.9    6.8    63   11.0 
2025-10-31 00:00 UT   01 16 59.8   +06 25 36     1.373    2.339  162.7    7.3    63   11.0 
2025-11-01 00:00 UT   01 16 23.9   +06 15 48     1.379    2.341  161.5    7.7    63   11.0 
2025-11-02 00:00 UT   01 15 49.2   +06 06 12     1.385    2.343  160.3    8.2    63   11.1 
2025-11-03 00:00 UT   01 15 15.7   +05 56 48     1.391    2.345  159.1    8.7    63   11.1 
2025-11-04 00:00 UT   01 14 43.3   +05 47 35     1.398    2.347  157.9    9.2    63   11.1 
2025-11-05 00:00 UT   01 14 12.2   +05 38 34     1.405    2.348  156.7    9.6    63   11.2 
2025-11-06 00:00 UT   01 13 42.4   +05 29 46     1.412    2.350  155.5   10.1    63   11.2 
2025-11-07 00:00 UT   01 13 13.9   +05 21 11     1.419    2.352  154.4   10.5    63   11.2 
2025-11-08 00:00 UT   01 12 46.7   +05 12 48     1.427    2.354  153.2   10.9    63   11.3 
2025-11-09 00:00 UT   01 12 20.9   +05 04 40     1.435    2.356  152.0   11.4    63   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.