Hairy Star – Comet 46P! Look up and get lost!
Since as far as our memory lanes take us, hairy stars have been a topic of fascination. Hairy stars? Well, in more common terms, a comet! Comet is derived from the Greek word ‘Kometes’ which means hairy stars. Comets have a atmosphere around them as they get closer to the Sun which is formed by the vapourising of ice on its surface. This atmosphere, called coma, gives the comet the appearance of a bright star with coloured hair around it when observed from Earth, hence the name.
Comets have been both a harbinger of joy and fear for people. Societies look upon them as bad omens that bring with them floods and famine, or as signs of good luck that bring along blessings and power to the kingdom. But all this speculation is for astrologers, us astronomers just want to gaze at these beautiful objects all night as they pay us a visit occasionally. So, is there a comet approaching us in the near future? Well, buckle up, because we indeed have a guest in our skies.
This year is ending with a nice visit from the comet 46P also called comet Wirtanen, so named after its discoverer, Carl M. Wirtanen who discovered the comet in 1948 from Licks Observatory. While 46P is a periodic comet with a revolution period around the Sun of 5.4 years, what makes this particular apparition special is that it will be on its brightest and closest approach to our planet in 20 years. So unless you want to postpone your comet gazing plans to after 20 years, keep reading on!
Comet Wirtanen: An Introduction of Comet 46P
Comet Wirtanen or 46P, is of the Jupiter family of comet, thus having a elliptical orbit that has its aphelion (farthest distance from the Sun) near the orbit of Jupiter at about 5 or 6 AU(astronomical unit) i.e. the average distance between the Sun and the Earth). The comet, though small, is nothing less than a hotspot of scientific curiosity. This 1.2 km big chunk of space rock has unusually high amount of water vapour in its coma compared to other comets of his family. Studying this comet is an important aim to understand the origins of life and the solar system much better, along with understanding the dynamics of comets. This is evident from the fact that 46P was the original destination of research for the Rosetta spacecraft, but since the ESA team could not meet the launch window for this comet, the destination was changed to the comet 67P or Churyumov-Gerasimenko, which it reached successfully and started studying in the year 2014. Its not just the Europeans who have their eyes on this comet, but also the Americans. The ‘Comet Hopper’ mission was one of the three finalists for the NASA Discovery program. The mission had its objectives to study the coma, and the nucleus of comet Wirtanen, along with other objects in a total mission duration of around 7 years. The program though passed the proposal of the InSIGHT mission, a Mars lander, that successfully landed on Mars on 27th November, 2018 1:25 AM IST.
The debris of comet 46P is also responsible for the Piscid meteor shower, which were first observed in August 2012, with an approximate ZHR of a dozen meteors.
While comets can be present in our skies for months, they can be viewed only through modest backyard telescopes. Its only when they come too close to Earth or are at their brightest when they are visible with the naked eye or binoculars, but only for a couple nights. Comets move faster in the sky compared to the background stars, and hence move from one constellation to the other during their month long visit in the Earth’s skies. Comet Wirtanen will be on its closest approach to Earth on 12th December, 2018, while it will be on its brightest on 16th December, 2018. The expected magnitude that the 46P will reach on 16th December may be around 3, which means it can be visible with naked eyes in clear skies. Comets rise and set on average with the constellation in which they appear for the night. Currently as this post is being typed the comet is journeying through the constellation of the sea monster, Cetus. It will be entering the river constellation, Eridanus, in the beginning of December.
During its most prominent view, it will be in the constellation of the bull, the zodiac of Taurus, between the Pleaides and the Hyades clusters. This offers an incredibly nice frame to capture the comet for the astrophotographers.
To locate Taurus in the mid-December sky you can use android applications like Sky Map.
While, there are more hairy visitors lined up for the future, you should definitely not let go of the chance to observe comet 46P. Such important comet, combined with the near-perfect observing conditions is a golden opportunity for anyone who finds peace in the night sky.
Happy star-gazing and wish you clear skies specially during mid-December!
Sapna Educator SPACE Technology and Education Private Limited Watch and photograph the best meteor shower of the year along with the comet 46P/Wirtanen this December! Bookings open now @ Astroport India send your query at bit.ly/Astroport
Best photograph of Comet 46P by SPACE India team