Time is running out to see rare devil-horned comet
Acomet that has had a lot of “hype” in the media, mainly because of it having been called the “Devil Comet”, is technically currently visible in our Tasmanian evening skies, but you will need to know exactly where to look, and it will be tricky to see.
Binoculars will be helpful, and each evening there is a limited window of time during which to look.
Comets are icy objects, typically several kilometres across, that orbit the Sun. They do not “dash” across the sky.
Like planets, they appear in slightly different directions each night as they, like us, orbit our star.
The comet’s actual name is Comet 12P/Pons-Brooks. It was discovered by the French astronomer Jean-Louis Pons (1761-1831) observing from Marseilles in July 1812, and observations by Pons and others showed that it orbited the Sun about every 70 years.
In 1883, after the discovery of a comet by William Brooks (1844-1921) in the US, it was realised this was the same comet that Pons and others had seen in 1812, pinning down the size and shape of its orbit around the Sun with greater accuracy.
The “12P” in the name indicates that it is classified as a periodic comet (P) – one that has an orbital period of less than 200 years – and that it was the 12th to be discovered.
The reason that comets such as Halley and Pons-Brooks make infrequent appearances is that their orbits are very elongated, shaped like very thin ovals, taking them to great distances from the Sun.
They swoop through the inner Solar System, where we are located, every several decades, passing around the Sun before returning to the faraway extreme ends of their ovals.
For several nights to come, the comet will be located quite low in the northwest during the evening twilight, in the constellation of Taurus, the Bull.
The best time to watch for it will be about 6.30pm. It is expected to reach its brightest on Monday, but frustratingly, observing it has been somewhat hindered by the light of the nearly full Moon.
From this week, the comet fades naturally, but the moonless evenings later in the week may give us a better opportunity to spot it. So, what can we expect?
Despite the attention the comet has received, it is quite faint. To make matters worse, Tasmania is the worst place in Australia from where to see it.
I failed to spot it even using binoculars on Wednesday evening. So, if you remember the wonderful views we had of Comet Hyakutake in 1996 and the even brighter Comet McNaught in 2007 – indeed, I hope you do – Comet PonsBrooks is nothing like that.
Comets’ appearances are rather unpredictable even from night to night, but this comet’s most likely appearance will probably be, at best, a fuzzy patch of light through a pair of binoculars. You may have trouble seeing it with the unaided eye, and you are unlikely to get a good view of its tail, which is far more apparent in photographs. However, do have a look, just in case of an unexpected brightening.
The comet’s motion appears to be quite slow from night to night. Each evening it will appear a little higher at the same stage of twilight, being seen against a somewhat darker sky.
I have been asked why comet Pons-Brooks is called the “Devil Comet”.
It is brighter than it may have been, due to a series of outbursts in recent months that were probably caused by new icy material being exposed to the Sun.
This was not entirely surprising. Indeed, outbursts in brilliance have been observed for this comet at earlier passages around the Sun. This time, as the new material flowed away from the main body of the comet, it formed shapes that looked like horns!
Enjoy the view if you can spot Comet Pons-Brooks. It should remain visible in binoculars for the next week or two, and have another look in the year 2095 if you’re still around.
However, let’s hope that during our lifetimes, we see one or more other comets like 2007’s Comet McNaught, which was unexpected because it is on an orbit that results in its return to our vicinity only every several thousand years!