“Devil’s Comet” is finally visible to the naked eye under very dark skies

After 71 years, Comet 12P/Pons-Brooks has reached magnitude 5, the traditional point at which an object is considered visible without binoculars or telescopes. However, you will still need particularly fortunate circumstances to be able to discover it with just your eyes, although even small instruments will shift the odds heavily in your favor.

Pons-Brooks belongs to a rare class of comets known as the Halley type, with periods between 20 and 200 years. These contrast with the long-period comets that enter the solar system once every tens or hundreds of thousands of years. Such comets can be spectacularly bright (although most are not), but are inherently unpredictable. Short-period comets pass by regularly, but have lost so much of their ice through repeated close passes to the Sun that they are almost always faint.

Pons-Brooks doesn’t have the storied history of Halley’s Comet (no one pasted it into one of the most famous tapestries of all time), but it was still impressive on previous visits in 1385 and 1884.

It is also particularly sensitive to explosions that cause it to suddenly brighten. These were noted on previous visits and emerged last year when an eruption caused Pons-Brooks to jump five magnitudes (a factor of 100 in brightness). Those explosions flowed outwards along two paths around an obstacle, leading some to conclude that horns had grown, inspiring the name the Devil’s Comet. Others saw a similarity to the Millennium Falcon.

When the comet looked like the Millenial Falcon.

In July 2023, when the comet resembled the Millennium Falcon.

The eruptions are not really understood, but they are believed to be the result of ice volcanoes with gases dissolved in liquid hydrocarbons trapped in the ice and released when a fissure opens. Why Pons/Brooks is so sensitive to this, while most other comets are not, is a mystery that astronomers are eager to explain. However, it is not unique. The comet 29P/Schwassmann-Wachmann manages to undergo similar events regularly, despite never coming closer to the Sun than Jupiter.

It would make a lot of people very happy if Pons-Brooks timed another explosion when it was most visible, but unfortunately all we had on February 29 was a very small explosion, the effects of which have largely dissipated.

Nevertheless, the combination of getting closer to us and the surface ice turning to gas due to exposure to sunlight has caused a fairly gradual increase in brightness over the past two months. Recent observations confirm that Pons/Brooks has now crossed the magnitude 5 threshold.

Without instruments you still can’t see it from the city, and even small amounts of artificial light can interfere. The fact that the Moon is more than half full doesn’t help either.

While Pons-Brooks should become brighter each night over the next few weeks, it will also move closer to the sun in our sky. There is already a relatively short period after astronomical twilight when the comet is far enough above the horizon to be noticed, and that period is shrinking every day. The full moon next week will certainly not contribute to this.

For much of its approach, Pons-Brooks was so far in the northern sky that it was a nearly impossible object from the southern hemisphere, even for those with the right equipment. It has now moved a little further south, but is still far enough north that the difficulties in catching it described above are even worse if you are in Sydney or Sao Paulo.

However, after the comet makes its closest approach to the Sun on April 21, it will move further into the southern sky and the situation will be reversed. For observers in the Northern Hemisphere, the outer part of the journey will be very difficult to capture indeed, while observers in the South may get a pretty good chance, although still only if there is nothing blocking their view to the west shortly after sunset .

There is extra interest in Pons-Brooks this time because it is only 25 degrees from the sun on April 8. That means those lucky enough to see the upcoming total solar eclipse may be able to look east from the sun and see the sun. comet. That won’t be easy; it will probably be just at the edge of view, but it will be between Mercury and Jupiter in the sky and provide a guiding light.

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