C/2020 S8 (Lemmon)
ephemeris	date	magn	radius	delta	ra	dec	elong	phase	PA
Perihelion	10 Apr 2021	15.7	2.355 AU	1.468 AU	15h04m	+15°10'	144.3°	14.4°	232°
Nearest approach	23 Apr 2021	15.7	2.360 AU	1.410 AU	14h10m	+12°36'	154.9°	10.4°	185°
Today	27 Oct 2025	28.0	13.364 AU	12.991 AU	05h12m	-42°55'	110.0°	4.0°	311°

The interactive orbit chart above shows the comet'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.)

Light curve

The light curve chart below shows the estimated development of the comet's magnitude. Blue and black dots are visual and photometric CCD observations from COBS. This lightcurve is being recalculated every 6 hours based on the available COBS/MPC observations (currently 11.2 + 5 log[∆] + 10.0 log[r]). An additional green curve is displayed when an increase in apparent brightness is expected due to forward scattering of sunlight, which occurs when a dust-rich comet is located between the Earth and the Sun. (See Marcus 2007)

Charts

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

The following chart shows the short-term path of the comet in a field of view that is optimized for (~10x50) binoculars and finderscopes.

Orbital elements

The orbital elements of C/2020 S8 (Lemmon) are:

    e (Eccentricity)                : 0.9900630
    q (Perihelion distance)         : 2.3552250
    i (Inclination)                 : 108.55050
    Ω (Longitude of ascending node) : 23.98860
    ω (Argument of perihelion)      : 160.11260
    L (Longitude of perihelion)     : 30.55366
    B (Latitude of perihelion)      : 18.81410
    T (Time of perihelion passage)  : 2459314.75330
    P (Orbital period in years)     : 3648.93

    Epoch                           : 2025 Oct 26
    Reference                       : MPEC 2021-P47

    Classification(s):              : Nearly isotropic; Returning (a < 10000 AU); External (P > 200 years)

Ephemerides

Date       Time       RA (2000)    DEC (2000)    delta   radius  elong  phase   PA    magn
2025-10-26 00:00 UT   05 13 04.4   -42 51 08    12.989   13.354  109.5    4.0   310   28.0 
2025-10-27 00:00 UT   05 12 43.0   -42 53 45    12.990   13.360  109.8    4.0   311   28.0 
2025-10-27 14:58 UT   05 12 29.4   -42 55 22    12.991   13.364  110.0    4.0   311   28.0 
2025-10-28 00:00 UT   05 12 21.2   -42 56 20    12.992   13.366  110.1    4.0   312   28.0 
2025-10-29 00:00 UT   05 11 59.1   -42 58 51    12.994   13.372  110.3    4.0   313   28.0 
2025-10-30 00:00 UT   05 11 36.7   -43 01 19    12.996   13.378  110.6    4.0   314   28.0 
2025-10-31 00:00 UT   05 11 14.0   -43 03 43    12.998   13.384  110.8    4.0   315   28.0 
2025-11-01 00:00 UT   05 10 50.9   -43 06 04    13.000   13.390  111.1    4.0   316   28.0 
2025-11-02 00:00 UT   05 10 27.6   -43 08 22    13.003   13.396  111.3    4.0   318   28.0 
2025-11-03 00:00 UT   05 10 04.0   -43 10 35    13.005   13.402  111.5    3.9   319   28.0 
2025-11-04 00:00 UT   05 09 40.1   -43 12 45    13.008   13.408  111.8    3.9   320   28.0 
2025-11-05 00:00 UT   05 09 15.9   -43 14 52    13.011   13.414  112.0    3.9   321   28.0 
2025-11-06 00:00 UT   05 08 51.4   -43 16 54    13.014   13.420  112.2    3.9   322   28.0 

    Terminology:
            
    delta:  distance between comet and earth in AU
    radius: distance between comet 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-comet)    
    phase:  phase angle in degrees (angle sun-comet-earth)        
    AU:     Astronomical Unit (mean distance between earth and sun: 149597870.7 km      
    

Orbital elements usually provided by the MPC (Minor Planet Center).
Observations contributed by observers worldwide, via COBS (Comet Observation Database) or 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.