geoffrey.landis wrote:But an equatorial mount for the sky, and then composite in the foreground later, is simpler.
That is the most common way to make this type of shot. Note, however, that the sky image is still a composite, as the camera used is limited to a maximum exposure time of only a few minutes- definitely not 90 minutes.
Alternatively, by keeping the exposure time to 30 seconds or so, star trailing is minimized and the exposures can simply be stacked after aligning on the stars, and combined with a single longer exposure to capture the foreground.
Chris
***************************************** Chris L Peterson Cloudbait Observatory http://www.cloudbait.com
Of course, it must be 42. "The Answer to the Ultimate Question of Life, the Universe, and Everything was calculated by an enormous supercomputer over a period of 7.5 million years to be 42. Unfortunately no one knows what the question is. Thus, to calculate the Ultimate Question, a special computer was created, the size of a small planet, to use organic components, called "Earth."
Has any thought been given to capturing any of these showers before they hit the atmosphere? If we have a good approximation as to when they will arrive, why not try to grab some of them in that super-gel?
coxric1 wrote:Has any thought been given to capturing any of these showers before they hit the atmosphere? If we have a good approximation as to when they will arrive, why not try to grab some of them in that super-gel?
Particles large enough to produce meteors are too large to capture. But micrometeorites (dust) from showers are routinely captured by flying high altitude aircraft with sticky sheets on the wings, or similar techniques. And the microscopic (and occasionally not so microscopic) impacts from shower debris has been studied on various surfaces in space- some designed for that purpose, some not.
Even if we could capture larger particles in space, statistics make it hard. Even in the densest of meteor storms, any practical sized collection surface is unlikely to encounter even a single meteoroid. (Which is lucky, or else we'd not be able to operate satellites!)
Chris
***************************************** Chris L Peterson Cloudbait Observatory http://www.cloudbait.com
The Draconids meteor shower in 2011 was unusually active when it reached the peak time on October 8. The above image is a composite result of wide-angle photos taken during 90 minutes of highest activity of the shower in the early evening of southern Spain. There are 40 meteors captured in this result. The Celtic ruins of Capote (4th century BC) was the imaging place of the photographer. Strong moonlight during the night hided away many of the faint Draconid meteors. The particles that caused these meteors were typically the size of a pebble and were expelled long ago from the nucleus of comet 21P/Giacobini-Zinner. Most of the above meteors can be traced back to a single radiant emanating from the constellation of the Dragon (Draco). Click on the constellation icon above the image to see the celestial figures and labels. Juan Carlos Casado/Starryearth.com
I counted 43 streaks, but I'm thinking that the extra long streak at the top of the image is in fact two meteor streaks overlaid, which puts my final answer/guess at 44 meteors. Although I wish the answer was 42 to give us another question to that ultimate answer. :-/
I thought about that but decided it was too unlikely for them to be so perfectly overlapped.
I like the version of the image that shows the "celestial figures and labels" in Juan Carlos Casado's gallery in The World At Night (TWAN) website. It's well worth a look for those who have not seen it.
Edit added later. I have just found that the labelled version is brought up when moving a cursor over the image, so it's likely that most of you will probably have already seen it. Odd therefore that there seems to be no earlier comment(s) about that interesting version.
Last edited by DavidLeodis on Thu Oct 20, 2011 7:58 pm, edited 2 times in total.
superdave wrote:I could only see 5---ones who said 40 or more must have been imagining them---no way! The overlay of the constellation figures doesn't help any.
Click the image and you can see a larger one. I suspect you need some form of corrective lenses, also.
superdave wrote: I could only see 5---ones who said 40 or more must have been imagining them---no way! The overlay of the constellation figures doesn't help any.
Click the image and you can see a larger one. I suspect you need some form of corrective lenses, also.
A Draconid meteor burns up as a fireball in the atmosphere of Earth on 8 Oct 2011.
This video catches the moment when a Draconid meteor exploded in Earth's atmosphere earlier this month. The dramatic footage comes from a campaign to observe this important meteor shower using aircraft to beat the clouds.
On the evening of Saturday 8 October, Earth plunged through a stream of dust and rocks that had been expelled into space by the comet Giacobini–Zinner. The resultant meteor shower lit the skies over Europe with shooting stars.
The display radiates from the constellation of Draco, The Dragon, giving the name of "Draconids" to this shower which occurs at the same time every year as the Earth passes through the debris trail. In 2011, however, there was a difference. Astronomers had predicted an unusually high numbers of meteors as Earth was due to encounter particularly dense patches of the cometary detritus.
Detlef Koschny, leader of the Meteor Research Group at ESA, led the Agency's involvement in a project to find out if the prediction was right.
With cameras and other equipment packed into two Falcon-20 research planes, Detlef's colleagues took to the skies over Europe to rise above the clouds and watch for meteors.
"The Draconids peaked as predicted. A small peak at 17:30 GMT and then a larger one at 20:05 GMT," says Detlef.
The two planes flew on parallel tracks roughly 100 km apart as the researchers pointed their cameras at the same volume of Earth's atmosphere. The data they collected will allow each meteor to be triangulated, to determine its altitude and trajectory. Typically, meteors burn up between 80-120 km above the ground, well above the cruising altitude of an airliner. This will give updated information about the meteor stream itself, and the way the comet ejected the material.
It has been calculated that most of the meteors hitting Earth that night were ejected by comet Giacobini–Zinner in 1900 and have been circling the Sun ever since.
The team also recorded the spectrum of at least one meteor, which will reveal its chemical composition.
The Draconid meteor stream is important to understand because, like other streams, it can pose a danger to orbiting spacecraft. The tiny impacts can damage solar panels or sensitive optics.
The Draconids tend to be overlooked in favour of more visible displays such as the Leonids in November. This could be a mistake according to Detlef: "The Draconids move more slowly relative to Earth, so we don't see all of the smaller ones burning up. But they are still there, probably as many in number as the Leonids, only its harder to find them."
It's much more interesting to live not knowing than to have answers which might be wrong. — Richard Feynman
by Chris Peterson » Wed Oct 19, 2011 3:42 pm 
