21P/Giacobini-Zinner (Comet)

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From Fairfield , 21P/Giacobini-Zinner is visible in the morning sky, becoming accessible around 01:08, when it reaches an altitude of 21° above your eastern horizon. It will then reach its highest point in the sky at 05:08, 48° above your southern horizon. It will be lost to dawn twilight around 05:52, 47° above your southern horizon.

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Name 21P/Giacobini-Zinner
Object type Comet
Current position
Computed for:18 March 2024
Right ascension:16h00m [1]
Declination:-00°16' [1]
Constellation:Serpens Caput
Magnitude:20.39 (V) [2]
Distance:3.22 AU
26.74 lightmin [1]
Angular motion (speed):7.72 arcmin/day[1]
Angular motion (pos ang):260.9°
Orbital elements [1]
Semi-major axis:3.49 AU
Eccentricity:0.711182
Inclination:32.05°
Longitude ascending node:195.34°
Argument of perihelion:172.92°
Epoch of elements:18 March 2024
Mean Anomaly at epoch:303.76°
Absolute mag (H):9.40 [2]
Slope parameter (n):5.84 [2]
Derived quantities
Perihelion:1.01 AU
Aphelion:5.98 AU
Orbital period:6.53 years
Visibility from Fairfield

All times shown in Fairfield local time.

Events
25 Mar 2025  –  Comet 21P/Giacobini-Zinner passes perihelion
Additional sources

The position of this comet was calculated from orbital elements published by the Minor Planet Center (MPC).

We estimate the brightnesses of comets from magnitude parameters published by the BAA Comet Section, where these are available. These are computed from the observations they receive from amateur astronomers.

Comets are intrinsically highly unpredictable objects, since their brightness depends on the scattering of sunlight from dust particles in the comet's coma and tail. This dust is continually streaming away from the comet's nucleus, and its density at any particular time is governed by the rate of sublimation of the ice in the comet's nucleus, as it is heated by the Sun's rays. It also depends on the amount of dust that is mixed in with that ice. This is very difficult to predict in advance, and can be highly variable even between successive apparitions of the same comet.

In consequence, while the future positions of comets are usually known with a high degree of confidence, their future brightnesses are not. For most comets, we do not publish any magnitude estimates at all. For the few comets where we do make estimates, we generally prefer the BAA's magnitude parameters to those published by the Minor Planet Center, since they are typically updated more often.

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Fairfield

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41.14°N
73.26°W
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