HAMNET Report 16 December 2018

What do solar cycles, comets, and band aids all have in common? Well, they’re all in this bulletin!

Scientists at the Indian Institute of Science Education and Research, Kolkata, have come up with a path-breaking prediction for solar cycles, which affect numerous things in our daily lives, including space missions, global temperatures, radio communications, and more.

Writing in the Science section of ThePRINT this Friday, Sandhya Ramesh reports that Prantika Bhowmik, a PhD student at the Centre of Excellence in Space Sciences India (CESSI), and Dibyendu Nandi, her professor and co-author of the new paper, have devised a mathematical technique that predicts the next solar cycle ten years in advance. Their study was published in the journal Nature Communications last Thursday.

Sun spots have been observed and recorded for over four centuries, and it was found in the late 19th century that solar activity peaks and lulls approximately every 11 years. The cycles were reconstructed by combing through history, all the way back to 1745. The cycle that commenced that year and ended in 1766 is numbered ‘1’.

The cycles, however, are not exactly 11 years long; they vary between 9 years and 14 years, although 11 seems the average length. The next one, Cycle 25, is set to begin whenever Cycle 24 ends, possibly in early 2020, when all the sunspots start reflecting a reversed magnetic orientation.

A solar cycle functions in ‘maxima’ and ‘minima’. The start of a cycle is at minimal solar activity. This slowly picks up till it peaks mid-cycle in a ‘maximum’, where there can be up to 200 sun spots a day, travelling across the surface of the sun as it rotates. Then solar activity starts coming down again in a ‘minimum’ towards the end of the cycle. At present, the activity is at a minimum between Cycles 24 and 25.

Two big teams of scientists attempted to predict Cycle 24. Both teams used the same data but arrived at opposite conclusions: One claimed the cycle will be low while the other said it would be harsher. Furthermore, all models of prediction could only predict the maximum of a cycle when the minimum had already begun.

So Bhowmik and Nandi set about refining it. The advent of machine learning and complex algorithmic modelling meant they could do much more than what had been done for Cycle 24.

Their model is driven by observed data.

First, they observed the sun spots and noted down parameters such as timings, frequency, and ‘tilt angle’.

They feed this information about these spots into the first part of the algorithm which maps the polar flux on the sun’s surface, using magnetic field evolution models. Once that is mapped, it is used as input to the next part of the algorithm, which uses a dynamo model to predict what happens inside of the sun.

The algorithm then spits out the final prediction which combines the predictions for the upcoming minimum and the following maximum. Once the maximum is predicted, the decline is easy to predict.

Bhowmik and Nandi’s methods have been retro-tested for the data from the previous 100 years, and managed to accurately predict past cycles. They increase the prediction window to nearly 10 years, a historic high.

The model finds that there is not a lot of difference between the current and next solar cycle. In fact, Cycle 25 could even be slightly harsher than 24, with more sun spots. This becomes pertinent once again, especially since more and more nations are sending up satellites and other missions, including the Indian Space Research Organisation (ISRO), which has a whole host of launches lined up.

“Cycle 25 is expected to peak around 2024, so if ISRO is planning any interplanetary or trans-lunar missions, it would be safe for them to launch at least a couple of years before or after the peak,” said Bhowmik.

The study was supported by India’s ministry of human resource development, the Indo-French Centre for the Promotion of Advanced Research, and NASA.

Thank you to ThePRINT for that news.

Then, a reminder that today, the 16th of December, marks the closest approach to Earth of the Comet 46P/Wirtanen, which will be visible this evening, clouds permitting, in the Northern sky, between the red star Aldebaran, part of the constellation Taurus, to the left of Orion’s famous belt, and the Pleiades cluster, also called the “Seven Sisters”. So, go outside tonight at about 10pm, let your eyes get accustomed to the gloom, see if you can recognise Orion standing on his head, and look slightly to the left and higher up than Orion for the reddish Aldebaran, and then a little further West. Between Aldebaran and the “Seven Sisters”, you might see a greenish glow, slightly bigger than the customary size of the moon, that is the dust cloud around comet 46P/Wirtanen. A pair of binoculars of magnification 7 to 10 times, will make the comet more visible. After about Tuesday, the Moon will be in the evening sky, and block out your vision of the comet. So now’s your chance. Good luck!

Now, for all the cowards out there, pulling off a Band-Aid may soon get a lot less painful!

Researchers from the Harvard John A. Paulson School of Engineering and Applied Sciences (SEAS) and Xi’an Jiaotong University in China have developed a new type of adhesive that can strongly adhere wet materials—such as hydrogel and living tissue—and be easily detached with a specific frequency of light.

The adhesives could be used to attach and painlessly detach wound dressings, transdermal drug delivery devices, and wearable robotics.

The paper is published in Advanced Materials.

“Strong adhesion usually requires covalent bonds, physical interactions, or a combination of both,” said Yang Gao, first author of the paper and researcher at Xi’an Jiaotong University. “Adhesion through covalent bonds is hard to remove, and adhesion through physical interactions usually requires solvents, which can be time-consuming and environmentally harmful. Our method of using light to trigger detachment is non-invasive and painless.”

The adhesive uses an aqueous solution of polymer chains spread between two, non-sticky materials—like jam between two slices of bread. On their own, the two materials adhere poorly together but the polymer chains act as a molecular suture, stitching the two materials together by forming a network with the two pre-existing polymer networks. This process is known as topological entanglement.

These two hydrogels, adhered with an aqueous solution of polymer chains, come apart easily In the presence of UV light. Without UV light, the hydrogels are adhered strongly to one another and don’t come apart easily. When exposed to ultra-violet light, the network of stitches dissolves, separating the two materials.

There is, at last, hope for all of us who don’t enjoy having plasters ripped off our skin!

This is Dave Reece  ZS1DFR  reporting for HAMNET in South Africa.