Category Archives: Comets
Update (2013-06-11): it looks like no outburst was seen. The meteor shower will remain elusive for another while…
On 11 June 1930, three meteor observers in Maryland (USA) witnessed a flurry of shooting stars originating from the constellation of Delphinus. The mysterious meteor shower, called the gamma-Delphinids, lasted less than 30 minutes. The shower had never been seen before, and it has never returned since… until this year?
The gamma-Delphinids are one of a dozen rare meteor showers for which only anecdotal evidence exists. Such showers are thought to be caused by the dust trails of unknown long-period comets.
Meteoroid streams from long-period comets are thought to be very narrow. In fact the dust trails are so compact that our planet only encounters them when the gravitational pull from Jupiter and Saturn steers the stream exactly into Earth’s path. In contrast, famous meteor showers such as the Perseids and the Leonids originate from known short-period comets. Such streams are more widely dispersed due to their frequent exposure to planetary perturbations and solar radiation in the Solar System, and hence Earth encounters those short-period streams every year.
On 11 June 2013 near 8:30 UT, Earth is predicted to encounter the gamma-Delphinids for the first time since 1930. By measuring the time of the outburst, or its absence, we’ll be able to establish whether the shower is real, and learn about its origin. This is important because it teaches us about a large, Earth-crossing comet which we haven’t discovered yet.
Observers in North and South America are best placed to observe the event. Green and yellow areas in the map below indicate parts of the world where the sky will be dark, and the radiant above the horizon, near the predicted time of the meteor shower.
Two weeks ago, I posted an animation on YouTube showing where Comet PanSTARRS would be visible. The video attracted more than 15 000 hits, and although this is not a proper statistical analysis, I would like to draw attention to an interesting result in the demographic analytics provided by YouTube: 75% of the viewers were male.
Although the numbers are only based on the ~20% of viewers which were logged into a YouTube account while watching, statistics like these may reveal broad trends about the public interest in astronomy. If we were to assume that all people interested in astronomy are equally likely to have watched the animation, and if in addition we assume that these people are all equally likely to have a YouTube account regardless of their age/gender, then one might conclude that (middle-aged) men are twice more likely to seek for comet information than women. Interestingly, this is broadly consistent with the (unfortunate) trend of large male majorities in astronomy clubs and university departments.
There is no doubt that the above assumptions are wrong to some degree, and that the YouTube statistics are hence biased. It is not clear how severe the bias is however. I tried Googling for demographic statistics of YouTube users in general, but could not find consistent information. (Does anyone know a reliable source? Are 75% of YouTube users male anyway?!)
If the biases can be accounted for using a proper statistical analysis, then the analytics offered by science-themed YouTube videos would provide a way to measure the public interest as a function of age, gender and topic.