Why do I call the comet of the Christmas - when writing the present rows - this celestial wanderer approaching our planet? The answer is simple: the professional and amateur astronomers will look up to the sky many times around Christmas 2018 for a comet, which has benn discovered by the American astronomer Carl Alvar Wirtanen in 1948 comes to the historic proximity to us. The distance from our planet will the tenth closest modern comet and when we look at all the comets known by mankind, it will be the sixteenth closest to us. The comet 46P/Wirtanen at the time of its proximity to 2018, traveling 11.5 million kilometers next to our planet, a distance thirty times the average distance of the Earth-Moon. The list of closest comets to the Earth is led by the 1770 Lexell comet (D/1770 L1). This comet missed the Earth just 2.2 million kilometers.
Thanks to the diatomic carbon molecules, this celestial wanderer with a green coma, orbit around the Sun between the Jupiter and Earth orbits, with a period of only 5.43 years. The observability of 2018 has been the best since it was discovered. Especially favored by the proximity to the Earth is that from the second half of December 2018 the comet can be seen as a circular polar body from Hungary, but of course it is advisable to observe at its transit - around midnight.
Interestingly, the comet's Rosetta spacecraft mission was also designed for this comet, but due to a lack of time, another body had to be chosen. Finally, Rosetta's journey was directed at the 67P/Churyumov–Gerasimenko comet, where it conducted researches between 2014 and 2016 and landed his landing unit Philae in 2015 on the comet's surface.
The Wirtanen comet is one of the "hyperactive" comets. The Jupiter comet family's celestial wanderer is characterized by high levels of dust and gas emissions - fortunately! It is predicted that there may be up to 3 magnitudes at the time of proximity. This means that you can even see it from an avarage light polluted place. More pessimistic estimates tend to predict brightness between 4-5 magnitudes.
At the time of the capture, Wirtanen was still quite low in height above the horizon from Hungary, and the weather is not always gracious to me in the December nights, so I decided to capture the approaching comet with remote control (using an Australian robotic telescope). It gave a fantastic sight: a 30' coma with a narrow almost two degree long tail.
In determining the exposures, I tried to use short shutter speeds to make the comet's own movement, otherwise fast, in the pictures insignificant. Interestingly, the 14.2 magnitude NGC 965 spiral galaxy can be discovered in the field of view, but there are also a number of PGC-flagged galaxies.
Let us hope that, with the confirmation of the optimistic predictions and the weather in our country will be clear and we will see a memorable Christmas comet for all of us.
17 Dec 2018: The comet passes next to the Pleiades
23 Dec 2018: The comet passes next to the Capella
R.A. 02 h 35 m 10 s Dec. -19° 07′ 10″
Distance from Sun:
160 million km
Distance from Earth:
17.7 million km
Coma: 30'; tail: 1,8° (PA: 45°)
01/12/2018 10:34-11:00 UT
Total exposure time:
iTelescope - T8, Siding Spring Observatory, Australia
FLI Microline 16803
Tele Vue 127/680 mm ED refractor
10Micron 2000 HPS
Focal ratio, length:
f/5.3, 680 mm
1 x 300 s Lum, 1 x 180 s R, G, B
PixInsight, Adobe Lightroom, Adobe Photoshop