I read an article about the comet 46P / Wirtanen, discovered in 1948 by the American astronomer Carl Alvar Wirtanen, is approaching the Earth. Despite having only 1.2 km in diameter (a space mound), it should shine in the sky for several days, because, in mid-December, it will be very close to both the Earth and the Sun.

Comet 46P / Wirtanen seen on November 10th from Namibia: the crown (the green halo surrounding the comet) and the tail of particles pushed away by the Sun are clearly visible.

 A LUCKY COMBINATION. When they are closer to the Sun (ie perihelion), it is the period of greatest visibility for comets: heat evaporates the surface layers and the material that they lose forms the foliage and the tail.46P / Wirtanen will reach the perihelion around December 16th, a period around which it will be closer to the Earth, just 11.5 million km from us (the Moon is from us, on average, about 400,000 km).


UNPREDICTABLE. The maximum brightness expected is magnitude 3, or rather bright enough to be seen, at night, where there is no light pollution, but probably obscured by city lights. However, the response of comets to heat and solar wind is always unknown, so this prediction could be disregarded or even exceeded!

HOW TO LOOK IT To be more likely to see it, you have to wait until at least the beginning of December, find an illuminated area little or nothing far from the city and, armed with binoculars and star charts, after sunset, look towards the east, in the constellation of Taurus.To distinguish it from the stars just look for a non-flickering dot.



THE PLAN B. If the comet 46P / Wirtanen were to disappoint the expectations, you can look for consolation in a great classic: the images of the comet 67P / Churyumov-Gerasimenko. It would not even be a great wrong: initially, the mission of the Rosetta probe had to be directed to 46P / Wirtanen.