July 30, 2014

AstroEvent: A Wild Card Meteor Shower.

Comet 21P Giacobini-Zinner. (Credit: NASA).

Comet 21P Giacobini-Ziner. (Credit: NASA).

 

   Sure, everyone’s heard of the Leonids and the Perseids, but have you ever stood vigil for… the Giacobinids? Also sometimes referred to as the Draconids, this sporadic shower tends to go unnoticed on most years. Radiating from the circumpolar constellation Draco, the Giacobinids produce a lackluster <5 meteors per hour… so, why the fuss? Well, the Giacobinids have been known to occassionally put on a show approaching 1,000+ storm level activity, most notably on the years 1933, 1946, and most recently, 1998. This seems to occur with the perihelion passage of the showers’ parent comet 21P Giacobini-Ziner (hence the bizarre name).   This occurs again in 2011, and it’s worth watching for storm level activity on either year surrounding that date. The Giacobinids arrive around October 7-8th, and the good news this year is that the Moon is New on October 7th. The radiant for this shower also transits in the late evening hours, so unlike many meteor showers, you may see increased activity shortly after dusk… will the Giacobinids perform this year? The only way to know for sure is to watch!   

This week’s astro-word is Ablation Cascade. Not everything in the night sky that looks like a dust grain meteor is; a satellite on re-entry can mimic the same style of brilliant bolide fireball. Also sometimes referred to as the Kessler syndrome, this scenario was first theorized by NASA researcher Donald Kessler in 1978. The fear is that as the amount of space junk accumulates in Low Earth Orbit, (LEO) a threshold may be reached whereby the shrapnel from one satellite collision may serve to trigger more. Already, we’ve witnessed the first sat-on-sat collision recently, with the destruction of an Iridium and defunct Cosmos satellite. What would be the actual tipping point of orbital density is unclear. Ideas to “cleanup” LEO include using lasers to target larger fragments and requiring that newer satellites can either be de-orbited or have the capability to move into graveyard orbits when required. Space debris is a big concern for the International Space Station, currently by far the largest thing in LEO. Won’t that be a spectacle on that (hopefully far off) day when the ISS gets de-orbited?

Trackbacks

  1. [...] artificial skies of the 20th and 21st century. Will the ring of satellite debris eventually seed an ablation cascade, breaking down into a great artificial new reef of debris encircling the Earth? What will the [...]

Speak Your Mind

*