(85) Io
ephemeris	date	magn	radius	delta	ra	dec	elong	phase
Today	15 Jul 2025	12.3	2.182 AU	1.931 AU	01h12m	+14°46'	90.0°	27.8°
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
2025-07-15 00:00 UT   01 12 54.5   +14 46 47     1.931    2.182   90.0   27.8   248   12.3 
2025-07-15 20:47 UT   01 13 57.6   +14 51 20     1.922    2.183   90.6   27.7   248   12.3 
2025-07-16 00:00 UT   01 14 07.3   +14 52 02     1.921    2.183   90.7   27.7   248   12.3 
2025-07-17 00:00 UT   01 15 19.3   +14 57 08     1.910    2.184   91.3   27.7   248   12.3 
2025-07-18 00:00 UT   01 16 30.2   +15 02 05     1.900    2.185   92.0   27.7   248   12.3 
2025-07-19 00:00 UT   01 17 40.2   +15 06 53     1.890    2.186   92.6   27.7   248   12.3 
2025-07-20 00:00 UT   01 18 49.2   +15 11 33     1.880    2.187   93.3   27.6   248   12.2 
2025-07-21 00:00 UT   01 19 57.2   +15 16 03     1.870    2.188   93.9   27.6   247   12.2 
2025-07-22 00:00 UT   01 21 04.2   +15 20 24     1.859    2.189   94.6   27.6   247   12.2 
2025-07-23 00:00 UT   01 22 10.1   +15 24 35     1.849    2.190   95.3   27.5   247   12.2 
2025-07-24 00:00 UT   01 23 14.9   +15 28 37     1.839    2.191   96.0   27.5   247   12.2 
2025-07-25 00:00 UT   01 24 18.6   +15 32 30     1.829    2.193   96.7   27.4   247   12.2 
2025-07-26 00:00 UT   01 25 21.2   +15 36 12     1.819    2.194   97.4   27.3   247   12.2 
2025-07-27 00:00 UT   01 26 22.7   +15 39 44     1.808    2.195   98.1   27.3   247   12.2 
2025-07-28 00:00 UT   01 27 23.0   +15 43 07     1.798    2.196   98.8   27.2   247   12.1 
2025-07-29 00:00 UT   01 28 22.1   +15 46 19     1.788    2.197   99.5   27.1   247   12.1 
2025-07-30 00:00 UT   01 29 20.0   +15 49 21     1.778    2.198  100.2   27.0   247   12.1 
2025-07-31 00:00 UT   01 30 16.7   +15 52 12     1.768    2.199  100.9   27.0   247   12.1 
2025-08-01 00:00 UT   01 31 12.2   +15 54 53     1.758    2.200  101.6   26.9   247   12.1 
2025-08-02 00:00 UT   01 32 06.5   +15 57 24     1.748    2.201  102.4   26.8   247   12.1 
2025-08-03 00:00 UT   01 32 59.4   +15 59 43     1.738    2.203  103.1   26.7   247   12.1 
2025-08-04 00:00 UT   01 33 51.1   +16 01 52     1.728    2.204  103.9   26.5   247   12.0 
2025-08-05 00:00 UT   01 34 41.4   +16 03 49     1.718    2.205  104.6   26.4   247   12.0 
2025-08-06 00:00 UT   01 35 30.5   +16 05 36     1.709    2.206  105.4   26.3   247   12.0 
2025-08-07 00:00 UT   01 36 18.1   +16 07 11     1.699    2.207  106.1   26.2   247   12.0 
2025-08-08 00:00 UT   01 37 04.4   +16 08 35     1.689    2.209  106.9   26.1   247   12.0 
2025-08-09 00:00 UT   01 37 49.4   +16 09 47     1.679    2.210  107.7   25.9   247   12.0 
2025-08-10 00:00 UT   01 38 32.8   +16 10 47     1.670    2.211  108.5   25.8   247   12.0 
2025-08-11 00:00 UT   01 39 14.9   +16 11 36     1.660    2.212  109.3   25.6   247   11.9 
2025-08-12 00:00 UT   01 39 55.5   +16 12 13     1.651    2.214  110.1   25.5   247   11.9 
2025-08-13 00:00 UT   01 40 34.6   +16 12 38     1.641    2.215  110.9   25.3   247   11.9 
2025-08-14 00:00 UT   01 41 12.3   +16 12 50     1.632    2.216  111.7   25.1   247   11.9 

    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.