The faiding Comet 46P/Wirtanen seen in Cazalla de La Sierra

The faiding Comet 46P/Wirtanen seen in Cazalla de La Sierra

As comet 46P/Wirtanen keeps travelling away from us, it also fades and gets dimmer, this large ball of ice (mainly water, methane, ammonia or carbon dioxide) and rock, is relatively small in size with an estimated diameter of just 1.2 kilometers. It was discovered by Carl A. Wirtanen in 1948 at the Lick Observatory, California via photographic plate.

Interestingly This icy world was the original intended target for ESA’s Rosetta spacecraft but the launch window was missed, so the comet 67P/Churymov-Gerasimenko was chosen ad a target for the Rosetta mission. The majority of Comets are hidden from sight, very far from the centre of our Solar System, either on the Kuiper belt or the Oort Cloud. 

Panoramic view of the northeastern sky from the observing site, where the comet lies.

Sky map with the comet 46P/Wirtanen in it

The Kuiper Belt is just outside the orbit of Neptune, having a distance from the Sun of between 30 AU to 100 AU, and it is estimated that may contain up to 35.000 objects with diameters greater than 100 km. The first of this was discovered in 1992, and the majority of periodic comets, such as Halley's Comet, come from the Kuiper belt.

However, the Oort Cloud is much farther away, estimated at 50.000 AU from the Sun, perhaps containing billions of comets too far away for us to detect. This is place is what produces the'non-periodic' comets, although they actually are periodic, but their orbital period may be more than one million years! Occasionally, a comet is deflected into a new orbit that takes it close to the Sun, and it becomes visible to observers on Earth.

Comet 46P/Wirtanen on December 30th of 2018 from Cazalla de La Sierra, Spain.

At the time of this observation, on December 30th of 2018, the Comet 46P/Wirtanen which is a short-period comet with an orbital period of 5.4 years, was in the constellation of Lynx, with and Azimuth: 42" 9.256' and an Altitude: 35" 46.948'. the distance from observer was: 0.116702976 au and from the Sun: 1.082739595 au.

Right ascension 7h 43m 12s

Declination: 56º 32’ 07” 

Apparent magnitude: 4.8

Angular size: 0.24 arc seconds

Disk illumination: 93%

The location was in Cazalla de La Sierra: Coordinates: 37° 56′ 31″ N 5° 42′ 09″ W

Radiance information: 0.31 W/cm^2 * sr

Elevation: 556 meters.

The Milky Way in the direction of Cygnus, from the place of observation.

The Orion Belt and the Orion Nebula, also known as Messier 42, M42, from the observation site.