Comets for Celestia

[EarthMoon]

As there is an Asteroids for Celestia topic, I thought it would be a good idea to create one for (real, not fictional) comets too ...

So, feel free to post your addons about comets, fragments, moons of them (or links to other threads that contain comets) below ...

Add-on by me: All comets of 2023: https://celestiaproject.space/forum/viewtopic.php?f=23&t=24376

[DaveBowman2001]

Here are the list of comet addons with customized models, textures, and/or trajectories for Celestia:

• 1P/Halley
• 9P/Tempel
• 19P/Borrelly
• 26P/Grigg-Skjellerup
• 67P/Churyumov-Gerasimenko
• 73P/Schwassmann-Wachmann
• 81P/Wild
• 96P/Machholz
• 103P/Hartley
• C/2012 S1 (ISON)
• C/2013 A1 (Siding Spring)
• C/2022 E3 (ZTF)
• C/2023 A3 (Tsuchinshan-ATLAS)
• C/2023 P1 (Nishimura)
• D/1993 F2 (Shoemaker-Levy)
  

[EarthMoon]

This addon adds 4 comets called "Gehrels" (270P/Gehrels, 90P/Gehrels 1, 78P/Gehrels 2 and 82P/Gehrels 3) to Celestia. Three of them (not 90P) had/have many flybys at the gas planets, and 78P was in a 2:1 resonance with Ceres (Ceres finishes 2 orbits while the comet finishes only 1) 4 times (many orbits each), separated by Jupiter flybys (they didn't ruin the 2:1 resonance with Ceres). 90P has a (much) stable orbit around the sun which doesn't change that much because it didn't/doesn't fly by Jupiter or Saturn closely.
All four comets have .xyzv trajectories for high precision which start at 1600 Jan 01 and end at 2500 Jan 01.

Note: The P designations (e.g. 1P, 2P, etc.) are in a different order than the comet numbers (Gehrels (1/2/3)) for some reason which caused little confusions but everything is fine now.

Flyby data (also available in flybys.txt inside the .zip):

Code: Select all

Fly-bys on planets:

   Year   Object   Distance
270p
   1843   Saturn   Far
   1895   Jupiter   Medium
   1987   Saturn   Medium
   2046   Jupiter   Medium
   2072   Saturn   Medium
   2131   Saturn   Far
   2250   Saturn   Far
   2343   Jupiter   Medium
   2390   Jupiter   Medium
90p
   [None]
78p
   1675   Jupiter   Medium
   ....   Ceres   Far
   1723   Jupiter   Medium
   ....   Ceres   Far
   1805   Jupiter   Medium
   ....   Ceres   Far
   1853   Jupiter   Medium
   ....   Ceres   Far
   1889   Jupiter   Medium
   1911   Jupiter   Medium
   1914   Ceres   Far
   1957   Ceres   Medium
   1971   Jupiter   Medium
   1994   Jupiter   Medium
   2011   Ceres   Far
   2026   Ceres   Far
   2029   Jupiter   Close
   2046   Jupiter   Close
   2123   Jupiter   Medium
   2129   Jupiter   Close
   2236   Jupiter   Medium
   2239   Saturn   Medium-Far
   2265   Neptune   Medium
   2311   Saturn   Close-Medium
   2427   Neptune   Medium
   2484   Jupiter   Medium
82p
   1600   Saturn   Medium
   1622   Jupiter   Far
   1637   Saturn   Far
   1669   Saturn   Medium
   1730   Jupiter   Medium
   1785   Jupiter   Medium
   1834   Jupiter   Medium
   1901   Saturn   Far
   1970   Jupiter   Close (Orbit Start)
   1973   Jupiter   Close (Orbit End)
   2000   Jupiter   Medium
   2057   Jupiter   Close (Orbit Start)
   2063   Jupiter   Close (Orbit End)
   2122   Jupiter   Medium
   2147   Jupiter   Close (Orbit Start)
   2151   Jupiter   Close (Orbit)
   2153   Jupiter   Close (Orbit End)
   2194   Jupiter   Medium
   2235   Jupiter   Medium
   2239   Jupiter   Close (Orbit Start)
   2243   Jupiter   Medium (Orbit End)
   2298   Saturn   Far
   2358   Saturn   Medium
   2446   Saturn   Medium
   2493   Jupiter   Close


.... = between the before and following year
Orbit Start = captured into orbit around that object
Orbit = during orbit around that object
Orbit End = left orbit around that object


[SpaceExplorer]

2P/Encke is a periodic comet with an orbital period of 3.30 years and a diameter of 4.8 km. It was first observed in 1786 and identified as periodic in 1819.
Its last perihelion occurred on 2023-Oct-22 and the next will be on 2027-Feb-10. Encke makes a notable close approach to Mercury on 2013-Nov-18, at a distance of 3.73 million km.

XYZV trajectory with data from JPL HORIZONS. The "comet.dds" texture is from Celestia Origin. Since Encke is also now included by default in Celestia 1.7.0, the "Replace" parameter is enabled.

[SpaceExplorer]

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[SpaceExplorer]

C/2024 L5 (ATLAS) is a comet discovered on 2024-Jun-14 by the Asteroid Terrestrial-impact Last Alert System (ATLAS). What makes this comet stand out is a close encounter with Saturn on 2022-Jan-24, which placed it on a escape trajectory (hiperbolic) from Solar System. Before this encounter, its orbit around the Sun was retrograde and similar to that of a centaur.

Some details of the trajectory of C/2024 L5:
- Closest approach to Saturn on 2022-Jan-24 02:50:00 UTC), 340,340 km.
- Reaches perihelion in 2025-Mar-10, 3.4322 AU;
- Closest approach to Jupiter in 2026-Aug-18, 0.59517 AU;

[SpaceExplorer]

C/2024 S1 (ATLAS) was a sungrazer and probable Kreutz comet discovered on 2024-Sep-27. It was predicted to reach perihelion in 2024-Oct-28, and if it survived the Sun's intense heat, it could potentially become visible to the naked eye during the day, with magnitude estimated to be between -5 and -7. However, just before reaching perihelion, the comet's nucleus completely disintegrated, as observed by SOHO LASCO.

NOTE: To see the comet, you need to set the time in Celestia to sometime before 2024-Oct-28 07:00 UTC

[SpaceExplorer]

An update for C/2024 S1 was posted to the original post above. The comet disintegrated just before perihelion. Furthermore, he was not hyperbolic (until then, the data were preliminary and the observation arc very short).

[SpaceExplorer]

C/2024 G3 (ATLAS) is a long-period comet discovered in 2024-Apr-5. It reached perihelion on 2025-Jan-13, when it reached an apparent magnitude of -3.8, probably being the Great Comet of 2025. However, it began to disintegrate during the second half of Jan-2025.

NOTE: To see the comet, you need to set the time in Celestia to sometime before 2025-Jan-20 00:00 UTC

[SpaceExplorer]

An update for C/2024 G3 was posted to the original post above. The comet disintegrated a few days after perihelion.

[DaveBowman2001]

Close encounter with Saturn in 1992

The orbits of 450P/LONEOS from 1900 until 2100.

450P/LONEOS is a 7-km wide periodic comet with a 22-year orbit around the Sun (as of 2022). Discovered in 2004, it was formerly a centaur until a close encounter with Saturn in 1992 significantly decreased its semi-major axis by 5.2 AU, which began its transition into a Jupiter-family comet in the next few centuries.

450P-LONEOS.zip

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