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| colspan="8" style="text-align:center;"|Perihelion distance<br/>at different epochs It was last observed in 2023 and will next come to perihelion in 2029.

Discovery

46P/Wirtanen was discovered photographically on 17 January 1948, by the American astronomer Carl A. Wirtanen. Between January 23 and September 26 of 2013, the comet had an elongation less than 20 degrees from the Sun.

On 16 December 2018, the comet passed from Earth, marking one of the 10 closest comet flybys of Earth in the last 70 years. was organized to capitalize on the favorable circumstances of the 2018 apparition.

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File:C46P-sky.png|Path of 46P across the sky during 2018. Its size shown is inversely proportional to its distance.

File:C46P-orbit.png|Orbital approach of 46P during 2018, moving south to north and crossing the ecliptic near its closest approach to Earth on December 16, 2018

File:Comet 46P Wirtanen on 12 December 2018.png|Amateur astronomical image of Comet 46P on 12 December 2018

File:Comet 46P Wirtanen STSCI-H-p1863.png|View from the Hubble Space Telescope on December 13, 2018

File:Animation of 46P／Wirtanen orbit.gif|File:Animation of 46P/Wirtanen orbit<br />

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thumb|Comet 46P/Wirtanen photographed in the southern hemisphere, from [[Balcarce Partido|Balcarce, Argentina.]]

Exploration proposals

thumb|In December 2018, comet 46P/Wirtanen passed within 11.6 million kilometres of the Earth.

thumb|[[Radar astronomy|Radar image of 46P/Wirtanen imaged by the Arecibo Observatory in 2018.]]

The comet was the target for the proposed Comet Hopper mission, which reached the finalist stage in the NASA Discovery program. It was one of only three missions in that selection to have a more detailed study. The selection process was ultimately won in 2012 by the InSight mission, a Mars lander. The Comet Hopper was designed to use the ASRG, the Advanced Stirling Radioisotope Generator.

The Comet Hopper mission, had it been selected, would have had multiple science goals over the 7.3 years of its nominal lifetime. At roughly , the spacecraft would rendezvous with Comet Wirtanen and begin to map the spatial heterogeneity of surface solids as well as gas and dust emissions from within its coma. The remote mapping would also allow for any nucleus structure, geologic processes, and coma mechanisms to be determined. After arriving at the comet, the spacecraft would approach and land, then subsequently hop to other locations on the comet. As the comet approached the Sun, the spacecraft would land and hop multiple times. The final landing would occur at 1.5 AU. As the comet approached the Sun and became more active, the spacecraft would be able to record surface changes.

Also, 46P/Wirtanen was the original destination of the European Space Agency's Rosetta spacecraft mission, but launch delays meant that the comet was no longer easily reachable and another periodic comet, 67P/Churyumov–Gerasimenko, was chosen as the mission's target instead.

Associated meteor showers

2023

Close approaches to Jupiter in 1972 and 1984 moved the comet's orbit closer to Earth, and as of epoch 2018 the comet has an Earth–MOID of . In 2023 Earth passed through a denser part of the 1974 meteoroid stream than Earth did in 2007.

Observers in Australia reported that on the night of December 14, 2012, as many as a dozen meteors were seen emanating from the predicted radiant in the constellation of Pisces.

References

  • 46P/Wirtanen at Gary W. Kronk's Cometography
  • 46P/Wirtanen at Seiichi Yoshida's website