C/2021 A2 (NEOWISE)
ephemeris	date	magn	radius	delta	ra	dec	elong	phase	PA
Perihelion	21 Jan 2021	11.4	1.417 AU	0.630 AU	09h07m	-37°49'	121.1°	36.5°	346°
Nearest approach	2 Feb 2021	11.1	1.427 AU	0.508 AU	07h28m	-10°40'	143.8°	24.1°	41°
Today	18 Aug 2025	59.2	14.099 AU	13.527 AU	20h36m	+41°45'	122.6°	3.5°	158°

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.)

The orbital elements of C/2021 A2 (NEOWISE) are:

            e (Eccentricity)                : 0.9938340
            q (Perihelion distance)         : 1.4167160
            i (Inclination)                 : 107.05880
            Ω (Longitude of ascending node) : 125.05470
            ω (Argument of perihelion)      : 338.80440
            L (Longitude of perihelion)     : 131.54467
            B (Latitude of perihelion)      : -20.22124
            T (Time of perihelion passage)  : 2459236.33840
            P (Orbital period in years)     : 3482.72

            Epoch                           : 2025 Aug 18
            Reference                       : MPEC 2025-A40

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

The light curve chart below shows the estimated development of the comet's magnitude. Blue and black dots are visual and photometric CCD observations respectively from COBS or the MPC. The gray curve is based on the absolute magnitude and slope parameter as calculated from the original MPEC, or the latest values provided by the MPC (13.50 + 5 log[∆] + 10.00 log[r]), whereas the red curve is being recalculated every 6 hours based on the available COBS/MPC observations (currently 6.19 + 5 log[∆] + 41.24 log[r]).

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.
A more printer-friendly version of the same chart can be found further down this page as well.

The following chart shows the current location of the comet in a smaller, upside-down telescopic field of view.

A printable version of the short-term path of the comet in a field of view that is optimized for (~10x50) binoculars and finderscopes.

Ephemerides:

Date       Time       RA (2000)    DEC (2000)    delta   radius  elong  phase   PA    magn
2025-08-18 00:00 UT   20 36 32.4   +41 47 41    13.523   14.094  122.5    3.5   159   59.2 
2025-08-18 20:02 UT   20 36 14.8   +41 45 43    13.527   14.099  122.6    3.5   158   59.2 
2025-08-19 00:00 UT   20 36 11.3   +41 45 19    13.528   14.100  122.6    3.5   158   59.2 
2025-08-20 00:00 UT   20 35 50.4   +41 42 54    13.534   14.106  122.6    3.5   156   59.3 
2025-08-21 00:00 UT   20 35 29.6   +41 40 26    13.539   14.112  122.7    3.5   155   59.3 
2025-08-22 00:00 UT   20 35 09.0   +41 37 54    13.545   14.118  122.7    3.5   154   59.3 
2025-08-23 00:00 UT   20 34 48.6   +41 35 18    13.551   14.124  122.7    3.5   153   59.3 
2025-08-24 00:00 UT   20 34 28.4   +41 32 39    13.557   14.130  122.7    3.5   151   59.3 
2025-08-25 00:00 UT   20 34 08.4   +41 29 57    13.563   14.136  122.7    3.4   150   59.3 
2025-08-26 00:00 UT   20 33 48.6   +41 27 11    13.570   14.142  122.7    3.4   149   59.3 
2025-08-27 00:00 UT   20 33 29.1   +41 24 23    13.576   14.148  122.7    3.4   148   59.3 
2025-08-28 00:00 UT   20 33 09.7   +41 21 31    13.583   14.154  122.6    3.4   146   59.3 

    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.