Tag Archives: comet

A Couple of Questions for Readers

Today I’m looking for insights from readers on two issues that were nagging me over the weekend.

The first issue has to do with the Fukushima nuclear accident and subsequent radiation fears, which I first brought up on this blog last week.   I’ve been thinking about how to write articles that explain radioactivity and radiation in rather plain language, and about what we know is dangerous and what we know is not.  One of the challenges is to confront the extreme irrationality of people’s fear of radioactivity.  I’d like to hear my readers’ opinions of where this fear really comes from.  One explanation of this fear that you’ll commonly read is that “radioactivity is scary because you can’t see or smell or feel it”.  But that makes no sense; you can’t see, smell, or feel viruses either, or low levels of chemicals, so why aren’t people equally afraid of those things?  Especially since the average person is far more at risk of getting cancer or other potentially deadly diseases from viruses (such as papilloma) or from chemicals (asbestos, benzene, etc.) then from radioactivity, despite all the atmospheric nuclear tests in the 1950s and 1960s and the Chernobyl and Fukushima nuclear plant accidents.  So I don’t think this explanation is correct; there are plenty of invisible scary things in the world, and people’s fears are totally out of proportion to the true risks.  I have my own suspicions as to the real causes, but I am wondering what my readers think.

The second issue is more technical. Comet ISON, dubbed, as is typical of our sensationalist age, “comet of the century” before it has even become easily visible [and it might still be a dud, or it might be the best of the year or even the last twenty years; but of the century? check back in 2099!]) is approaching the sun.  There is indeed the tentative possibility, if it survives its very close encounter with the sun on November 28th, that it will give us a spectacular early morning display in December.  In preparation, I’m wanting to read more details about the properties of cometary tails, which are generated by the physics of particles and fields (photons, ions, magnetic fields, momentum conservation, etc.).  [Here’s a nice video of ISON’s tail and its interaction with the solar wind, the stream of charged particles emanating from the sun; also visible to its upper right is Comet Encke, which by chance is also near the sun.  By the way you can also see, watching Encke, that its tail is not a trail; it does not point along its direction of motion but instead points away from the sun.] But I’ve been unable to find anything online other than vague descriptions with no technical information, or references to books or review articles from several decades ago.  Do any of my readers know of a roughly up-to-date technical introduction to the physics of comets’ tails?

Thanks!

A Comet (Etc.) Well Worth Seeing

I’m pleased to say that last night I found comet Pan-STARRS, which is gracing the western sky just after sunset, and so I can recommend now that you all give it a try.  Binoculars will definitely make it easier to find, and allow you to see more of it.  It looks great!  Here are some thoughts on how to find it, appropriate if you’re in a country at roughly the same latitude as the United States.  (If you live far to the north or far to the south, you’ll need to get advice from someone who found it in a latitude similar to yours.  I don’t believe people in the southern hemisphere can still see it.) Continue reading