APOD: Night of the Perseids (2010 Aug 14)

[APOD Robot]

Night of the Perseids

Explanation: On the night of August 12, from moonset until dawn was a good time to see meteors. Enthusiasts watched as comet dust rained on planet Earth, streaking through dark skies during the annual Perseid Meteor Shower. Anticipating the shower approaching its peak, astronomer Marco Verstraaten recorded a series of exposures capturing meteors over a period of 6 hours using a wide angle lens from a not-so-dark site in the Netherlands. Combining them still produced this dramatic night sky view with many colorful meteor streaks. The starry backdrop includes the Milky Way and even the faint Andromeda Galaxy, right of center. Although the comet dust particles are traveling parallel to each other, the shower meteors clearly seem to radiate from a spot on the sky in the eponymous constellation Perseus. The radiant effect is due to perspective, as the parallel tracks appear to converge at a distance. Bright stars in Perseus extend into the gap between the foreground trees.

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[gam]

All the meteor tracks appear to pass through the same sequence of colors. Why is that?

The stars in the background do not appear to have moved over the six-hour exposure. Why not?

The moderator says that the apparent divergence of parallel meteor tracks is due perspective. Rays of sunlight from clouds also seem to diverge for the same reason, I suppose, which gives one a clue about how great the distances of even earthly phenomena can be.

[orin stepanek]

what galaxy is that off to the right center? Is that Andromeda?
I was out for a while last night but wasn't able to see any meteror streaks.

[Case]

The stars in the background do not appear to have moved over the six-hour exposure. Why not?

It is a 30 second exposure, one of a series of exposures over a period of 6 hours. There are some image details in the EXIF data.

[Chris Peterson]

All the meteor tracks appear to pass through the same sequence of colors. Why is that?

The green color is from ionized oxygen, and only shows up for the right combination of temperature (which essentially means meteor velocity) and atmospheric concentration (which essentially means height). Since most of the meteors have similar velocity-height profiles, they also have similar colors.

The stars in the background do not appear to have moved over the six-hour exposure. Why not?

The exposures themselves as short enough that the stars don't move much. Each meteor image has been stacked after using the stars as alignment references, so the stars appear stationary. The only tricky bit is dealing with the foreground, which can only come from one exposure. The usual method is to mask it out on all but one image when stacking.

The moderator says that the apparent divergence of parallel meteor tracks is due perspective. Rays of sunlight from clouds also seem to diverge for the same reason, I suppose, which gives one a clue about how great the distances of even earthly phenomena can be.

The reasons are the same, although large distances are not required. The meteors are only about 100 miles away, similar to the distance to horizon clouds. But even train tracks appear to diverge as they approach you, and the distance there is only a mile or less. You can see the effect with wood or tile floors, inside a single room.

[León]

I wonder meteor showers have been used to set dates by the ancients.

Known since ancient meteorites attributed to the stones that were thrown the gods have not been marteria of analysis.

Only in 1798, when H. Brandes and J. Benzenberg demonstrate the extraterrestrial origin of the meteors.

Alejandro de Humboldt, when viewed from the city of Cumana, in the Captaincy General of Venezuela, a meteor shower, on November 12, 1799, ignores the nature of them. Today we know that it was the rain of the Leonids and what he observed was a true meteor storm, as they came to count more than 3,000 meteors throughout the night.

In front in the center of the image of my personal collection of stones is possible to observe a meteor

[Chris Peterson]

I wonder meteor showers have been used to set dates by the ancients.

That's a good question, one that doesn't have a solid answer. There are records from China describing events a few thousand years ago that we can now assign to specific showers. But I don't know of any evidence that ancient people recognized periodicity in meteor showers. Hard to imagine something like that not being noticed, though.

Known since ancient meteorites attributed to the stones that were thrown the gods have not been marteria of analysis.

Meteor showers don't drop meteorites. It is doubtful that ancients associated meteors and meteorites, although it is certainly true that some cultures did recognize meteorites as being different from terrestrial rocks.

In front in the center of the image of my personal collection of stones is possible to observe a meteor.

I see it. But the proper term is meteorite. A meteor is a flash in the sky.

[biddie67]

Leon - do you mean the little black stone? Where did you find it?

Chris - thanks for taking the time to give some info about the color in the meteor streaks and how the photo was created .... It seems that some of the ancient peoples that were so observant about annual sky events should have spotted at least the stronger annual meteor showers.

I haven't had any luck with viewing the Perseids - too overcast here for the last several days - phooey!!

[León]

In front in the center of the image of my personal collection of stones is possible to observe a meteor.

I see it. But the proper term is meteorite. A meteor is a flash in the sky.

If it is correct on my page in Spanish had placed well, but failed traducción. http://apodando.blogspot.com/

[FreekOne]

I was out two nights in a row, stargazing outside Timisoara, Romania - just a couple hundred miles from where the picture was actually taken. There weren't really as many meteorites as I saw in previous years but it was worth it, nevertheless !

During both nights I saw quite a few meteorites streaking the sky TOWARDS the radiant point in Perseus, rather than FROM it. I am now curious whether these were Perseid meteorites and if so, what is the explanation for their backwards direction ?

[FreekOne]

Ooopsie, got the picture location mixed with the one from August 12 (also about Perseids). Way more than 200 miles to Holland

I also apologize for the double posting, I suppose I should register an account so I can edit my posts.

[Quigley]

What is the best time to observe the galaxy Andromeda in our current summer night sky from North America?

[Marco Verstraaten]

The "background sky" image is actually a sandwich of 2 x 30 seconds exposures on 6400 ISO to reduce noise. The Perseids themselfs are stacked in this frame from other frames taken that night (6 hours). They have different exposure times and ISO settings (ISO 4000 mainly) for lightpollution reasons. The frames were captured with 2 camera's for overlap. (2nd camera is a D3)

Marco

[neufer]

I was out two nights in a row, stargazing outside Timisoara, Romania - just a couple hundred miles from where the picture was actually taken. There weren't really as many meteorites as I saw in previous years but it was worth it, nevertheless ! During both nights I saw quite a few meteorites streaking the sky TOWARDS the radiant point in Perseus, rather than FROM it. I am now curious whether these were Perseid meteorites and if so, what is the explanation for their backwards direction ?

Probably they were the Southern Delta Aquariids from Comet 96P/Machholz
(or possibly the Alpha Capricornids from Comet 169P/NEAT).

[color=#00FF40][b]S[/b][/color]outhern [color=#00FF40][b]D[/b][/color]elta [color=#00FF40][b]A[/b][/color]quariids & Alpha [color=#0080FF][b]CAP[/b][/color]ricornids are late July showers on the opposite side of the sky map from the [color=#FFAF00][b]PER[/b][/color]seids

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http://asterisk.apod.com/vie ... 20#p117678

Code: Select all

--------------------------------------------------------------------------------------------
Name  ↓                 Dates  ↓       Peak dates↓     R.A.    Dec. (km/s) ZHR   Rating
---------------------------------------------------------------------------------------------
Alpha Capricornids     3 July-15 August    30 July    20:28    -10    23     4   Medium
S. Delta Aquariids    12 July-19 August    28 July    22:36    -16    41    20   Strong
Perseids              17 July-24 August    12 August  03:04    +58    59    90   Strong
---------------------------------------------------------------------------------------------

[DavidLeodis]

The stars in the background do not appear to have moved over the six-hour exposure. Why not?

It is a 30 second exposure, one of a series of exposures over a period of 6 hours. There are some image details in the EXIF data.

Hi. I am wondering Case how you were able to get the EXIF data, as my attempts failed. However, using your link, I see that the image was taken on August 13 2010 at 12:51:25 AM (timezone not specified).

Looking out from my light polluted home I saw a nice bright meteor at about 00:10 on the 13th but that was all i saw in a 10 minutes look. Shame.

[rstevenson]

... I am wondering Case how you were able to get the EXIF data, as my attempts failed. However, using your link, I see that the image was taken on August 13 2010 at 12:51:25 AM (timezone not specified). ...

I'm not sure how Case did it, but when I open that image in GraphicConverter, my fave Mac OS X graphic tool, I can choose to Copy EXIF Data As Text (under the Edit menu) and I get a large quantity of information when I paste it into any text editor. I assume any good image program can do something similar. For example, in PhotoShop all of this info was contained in multiple tabs inside the File Info... window, from the File menu.

Rob

[DavidLeodis]

... I am wondering Case how you were able to get the EXIF data, as my attempts failed. However, using your link, I see that the image was taken on August 13 2010 at 12:51:25 AM (timezone not specified). ...

I'm not sure how Case did it, but when I open that image in GraphicConverter, my fave Mac OS X graphic tool, I can choose to Copy EXIF Data As Text (under the Edit menu) and I get a large quantity of information when I paste it into any text editor. I assume any good image program can do something similar. For example, in PhotoShop all of this info was contained in multiple tabs inside the File Info... window, from the File menu.

Rob

Thanks Rob.

I know I can get EXIF Data (or at least some of it) by clicking on Properties on my digital camera images and also some online images but that did not work for this APOD. I only have a basic image editing program and that did not give an EXIF Data for this APOD. I clearly need a better such program! The amount of information in EXIF data can be quite staggering!

[Chris Peterson]

I know I can get EXIF Data (or at least some of it) by clicking on Properties on my digital camera images and also some online images but that did not work for this APOD. I only have a basic image editing program and that did not give an EXIF Data for this APOD. I clearly need a better such program! The amount of information in EXIF data can be quite staggering! :)

There are a few nice Firefox plugins that will let you view the EXIF data for any image right in your browser. That's probably the easiest route if you don't have or need standalone imaging software.

[Case]

[The} image editing program did not give an EXIF Data for this APOD.

The image on the APOD page (1) doesn't have EXIF data, but the "high res" click-through image (2) does have the EXIF data embedded. Note that the image manipulation (stacking etc.) means that the EXIF data is only true for one of the source images used in this composite.

P.S. the Info window for Preview (the Mac OS image and PDF viewer) also shows (some) EXIF data in one of the tabs. It loads quite a bit faster than a full image editor, if you want just a quick peek.

I thought it was quite cool to find the online EXIF tool at http://regex.info/exif.cgi, both for sharing (linking) and not-downloading-anything.

[DavidLeodis]

[The} image editing program did not give an EXIF Data for this APOD.

The image on the APOD page (1) doesn't have EXIF data, but the "high res" click-through image (2) does have the EXIF data embedded. Note that the image manipulation (stacking etc.) means that the EXIF data is only true for one of the source images used in this composite.

P.S. the Info window for Preview (the Mac OS image and PDF viewer) also shows (some) EXIF data in one of the tabs. It loads quite a bit faster than a full image editor, if you want just a quick peek.

I thought it was quite cool to find the online EXIF tool at http://regex.info/exif.cgi, both for sharing (linking) and not-downloading-anything.

Thanks Case. I still do not get anything more than very basic imformation (image size and pixels) with the (1) and (2) links but wonder if such things as the date and time are not given may simply be because the image is not one but a composite, so a particular time and date may not be in at least basic EXIF date? The Jeffrey's online EXIF tool is fascinating and I even managed to find the right URL to work for the iamge (though it did not give a date ).

I like to try to find the date when APOD images were taken as that is often not given yet lots of technical photographic data is in the information with images.

[rstevenson]

... (though it did not give a date ).

I like to try to find the date when APOD images were taken as that is often not given yet lots of technical photographic data is in the information with images.

The APOD write up says the image was taken "the night of August 12". The EXIF data I got from the image says "Date and time of original data generation : 2010:08:13 00:51:25".

Rob