APOD: Meteors and Milky Way over Mount Rainier (2015 Aug 25)

[APOD Robot]

Meteors and Milky Way over Mount Rainier

Explanation: Despite appearances, the sky is not falling. Two weeks ago, however, tiny bits of comet dust were. Featured here is the Perseids meteor shower as captured over Mt. Rainier, Washington, USA. The image was created from a two-hour time lapse video, snaring over 20 meteors, including one that brightened dramatically on the image left. Although each meteor train typically lasts less than a second, the camera was able to capture their color progressions as they disintegrated in the Earth's atmosphere. Here an initial green tint may be indicative of small amounts of glowing magnesium atoms that were knocked off the meteor by atoms in the Earth's atmosphere. To cap things off, the central band of our Milky Way Galaxy was simultaneously photographed rising straight up behind the snow-covered peak of Mt. Rainier. Another good meteor shower is expected in mid-November when debris from a different comet intersects Earth as the Leonids.

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[e-Large]

"...over 20 meteors"?!? I make it closer to FIFTY!

[RocketRon]

Why would magnesium give a green colour ?
When it burns, as magnesium ribbon in the science lab, or as a flare etc, it gives a brilliant white light.

Nickel, on the other hand, does give a green tint in a flame test.
As do a number of other elements.....

[Nitpicker]

To cap things off, the central band of our Milky Way Galaxy was simultaneously photographed rising straight up behind the snow-covered peak of Mt. Rainier.

The aspect of this beautiful APOD is to the south-west, and the central band of the Milky Way is setting (down and to the right). Indeed, only the north-eastern part of Sagittarius is still visible, with the "teapot" and the galactic centre having already set behind the mountain, the peak of which is at an elevation of about 10°. Whilst it is not incorrect to say "rising straight up" in the explanation, it is perhaps a little confusing, if one also considers the diurnal motion of the heavens.

(I stopped counting at 20 meteors, too ...)

[neufer]

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[b][color=#0000FF]The natural colors of a meteor's emission lines. This spectrum of a Perseid was photographed by Julian Nott (U.C. Santa Barbara) using a digital camera equipped with a 1000 lines/mm objective grating during the Aurigid MAC test flight on August 13, 2007. Photo: NASA/Julian Nott (www.nott.com). [/color][/b]

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Why would magnesium give a green colour ?
When it burns, as magnesium ribbon in the science lab, or as a flare etc, it gives a brilliant white light.

Nickel, on the other hand, does give a green tint in a flame test.
As do a number of other elements.....

Cool flame oxidation tests are different from hot atoms?

<<Vivid colors are more often reported by fireball observers because the brightness is great enough to fall well within the range of human color vision. These must be treated with some caution, however, because of well-known effects associated with the persistence of vision. Reported colors range across the spectrum, from red to bright blue, and (rarely) violet. The dominant composition of a meteoroid can play an important part in the observed colors of a fireball, with certain elements displaying signature colors when vaporized. For example, sodium produces a bright yellow color, nickel shows as green, and magnesium as blue-white. The velocity of the meteor also plays an important role, since a higher level of kinetic energy will intensify certain colors compared to others. Among fainter objects, it seems to be reported that slow meteors are red or orange, while fast meteors frequently have a blue color, but for fireballs the situation seems more complex than that, but perhaps only because of the curiosities of color vision as mentioned above.>>

[Wally]

ehhhh, this picture looks like it's three different images photoshopped together..

[Boomer12k]

On a VERY clear day....I can see 5 mountains.....one of them is Mt. Rainer....
Mt. Jefferson
Mt. Hood
Mt. Adams
Mt. Rainer
and Mt. St. Helens....we had 1/8th of an inch of ash on our cars back then.

Wonderful image!

:---[===] *

[Boomer12k]

ehhhh, this picture looks like it's three different images photoshopped together..

A two hour Time Lapse Video...will give a ONE FRAME image that type of look....

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[MadMan]

I count 46 meteors

[George]

Look carefully, most of the meteor streaks exhibit a green emission which I take to be from ionized oxygen.

[Tszabeau]

ehhhh, this picture looks like it's three different images photoshopped together..

A two hour Time Lapse Video...will give a ONE FRAME image that type of look....

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Interesting. How does time-lapse video eliminate the arcs that are produced by the earth's rotation, as in a still-photo of stars, yet retain the streaks of the captured meteors?

[tetrodehead]

I agree with Wally. Several photos making one great piece of eye-candy.
If camera was fixed, stars moving for two hours would leave 30°trails, even with time-lapse.
If camera mount was motorised, the mountain and trees would have 'trails'.
Still, an impressive picture.

[Cousin Ricky]

According to the photographer:

[T]his image is the combination of 45 13 second images without a tracking mount. I manually aligned these images on the star field to put the meteors in their respective location.

[Wally]

The boundary between Mount Hood and the Milky Way is what makes it look artificial. Some of the trees in front of Mount Hood look layered on as well.

[Chris Peterson]

The boundary between Mount Hood and the Milky Way is what makes it look artificial. Some of the trees in front of Mount Hood look layered on as well.

Yes, it's a challenge to make composites like this look natural. There's a guy with your name who does shots like this, and they're even more artificial looking. I've only seen a few examples that really get it right. But they can still make good pictures.

[Wally]

The boundary between Mount Hood and the Milky Way is what makes it look artificial. Some of the trees in front of Mount Hood look layered on as well.

Yes, it's a challenge to make composites like this look natural. There's a guy with your name who does shots like this, and they're even more artificial looking. I've only seen a few examples that really get it right. But they can still make good pictures.

I see you live off of Highway 9 - in my younger days I used to ride a bike from Breckenridge to Hoosier pass. I sure miss those days and I sure miss looking at deep sky objects with my 6" Dynascope in those Colorado skies.

[Chris Peterson]

I see you live off of Highway 9 - in my younger days I used to ride a bike from Breckenridge to Hoosier pass. I sure miss those days and I sure miss looking at deep sky objects with my 6" Dynascope in those Colorado skies.

It was the dark skies that originally brought me here. And while there has been some creeping up of the light domes from Denver and Colorado Springs, they are mostly ignorable and the skies are still very dark.

[Ron-Astro Pharmacist]

I know what the green streaks are...

Comet Cleanser.jpg

but who's sending them?? And why?

All kidding aside I get the inference that the meteors are falling toward the mountain but aren't they really emanating from Perseus in the background? Especially my "green" one.

[neufer]

I know what the green streaks are... but who's sending them?? And why?

• Parent body Comet Swift–Tuttle could clean our clock:

<<Comet Swift–Tuttle is a periodic comet with an orbital period of 133 years. It is the largest Solar System object that makes repeated close approaches to Earth with a relative velocity of 60 km/s. An Earth impact would have an estimated energy of ≈27 times that of the Cretaceous–Paleogene impactor. Comet Swift–Tuttle has been described as "the single most dangerous object known to humanity".

Comet Swift–Tuttle is the parent body of the Perseid meteor shower, perhaps the best known shower and among the most reliable in performance. It was independently discovered by Lewis Swift on July 16, 1862 and by Horace Parnell Tuttle on July 19, 1862. It has a well determined orbit and has a comet nucleus 26 km in diameter.

In the discovery year of 1862, the comet was as bright as Polaris. The comet made a return appearance in 1992, when it was rediscovered by Japanese astronomer Tsuruhiko Kiuchi and became visible with binoculars. An unusual aspect of its orbit is that it is captured into a 1:11 orbital resonance with Jupiter; it completes one orbit for every 11 of Jupiter.

Upon its 1992 rediscovery, the comet's date of perihelion passage was off from the then-current prediction by 17 days. It was then noticed that, if its next perihelion passage (July 11, 2126) was also off by another 15 days (occurred on July 26), the comet would pass perilously close to Earth or the Moon on August 14, 2126. Given the size of the nucleus of Swift–Tuttle (26 km), this was of some concern. This prompted amateur astronomer and writer Gary W. Kronk to search for previous apparitions of this comet. He found the comet was most likely observed by the Chinese in 69 BC and AD 188, which was quickly confirmed by Brian G. Marsden. This information and subsequent observations have led to recalculation of its orbit, which indicates the comet's orbit is very stable, and that there is absolutely no threat over the next two thousand years. It is now known that the comet will pass 0.153 AU from Earth on August 5, 2126. It will be a bright naked-eye comet reaching about apparent magnitude 0.7.>>

<<Lewis A. Swift (February 29, 1820 – January 5, 1913) was an American astronomer. He discovered or co-discovered a number of comets, including periodic comets 11P/Tempel-Swift-LINEAR, 64P/Swift-Gehrels, and 109P/Swift-Tuttle (parent body of the Perseids meteor shower). He was one of the few people to see Comet Halley at two of its appearances, 76 years apart. Apart from comets, he also discovered hundreds of nebulae. One of them is IC 289.

Swift first became interested in astronomy as young boy after observing the Great Comet of 1843 while on his way to school in Clarkson, New York. His teacher initially dismissed his observation, but three days later the 'discovery' of the comet was announced. Swift conducted his early observations in Rochester, NY, 'lain out in the snow' in an alley on Ambrose Street or on the roof of Duffy's Cider Mill. Later he gained a patron in the Rochester patent medicine businessman Hulbert Harrington Warner, who financed the building of an observatory for Swift. A fund of $13,000 was raised to purchase a 16 inch telescope for Swift. Warner went bankrupt in the Panic of 1893, which ended his financial support, and Swift then went to California to become director of Mount Lowe Observatory, taking the 16 inch telescope with him.>>

[Ron-Astro Pharmacist]

I know what the green streaks are... but who's sending them?? And why?

• Parent body Comet Swift–Tuttle could clean our clock:

<<Comet Swift–Tuttle is a periodic comet with an orbital period of 133 years. It is the largest Solar System object that makes repeated close approaches to Earth with a relative velocity of 60 km/s. An Earth impact would have an estimated energy of ≈27 times that of the Cretaceous–Paleogene impactor.

That's interesting Art. Let's hope not. Sometimes you just get lucky. Like the photographer was in this nice image. In Seattle it's almost always "rainier".

And one more thing - great links today They answered many questions I've been really curious about. Thanks a bunch!!

[geckzilla]

A discussion on Twitter about whether the green comes from oxygen or magnesium as the APOD description says resulted in Bill Ward popping into the conversation to show us his meteor spectroscopy work:
https://britastro.org/node/5897

[Chris Peterson]

A discussion on Twitter about whether the green comes from oxygen or magnesium as the APOD description says resulted in Bill Ward popping into the conversation to show us his meteor spectroscopy work:
https://britastro.org/node/5897

Yeah, but keep in mind there's very little connection between the visual appearance of a meteor and the spectral lines that show up. Green meteors are green because of atmospheric oxygen.

[neufer]

A discussion on Twitter about whether the green comes from oxygen or magnesium as the APOD description says resulted in Bill Ward popping into the conversation to show us his meteor spectroscopy work: https://britastro.org/node/5897

Yeah, but keep in mind there's very little connection between the visual appearance of a meteor and the spectral lines that show up. Green meteors are green because of atmospheric oxygen.

Perhaps the tops of some green meteor trails are green because of atmospheric oxygen...but not the bottoms.

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Hi,

I think this is quite an interesting little [meteor trail] spectrum. 0508UT 15/3/15. Not very bright and very few lines visble. However it has exceptionally bright OI emission from the "forbidden" transision at 557.7nm. Looking at any other of my spectra here there is no comparable emission in any of them!

Due to the quantum mechanics involved this is a meta stable state, the O atoms sit excited for 0.74 seconds before emitting the photon. So it only occurs with meteors that are very swift and start to or completely abalate above ~100-110km. Below this the atmosphere quenches the transition through collisional loss.

The usual strong Mg and Na so looks like a stony job but it must have been coming straight at us for a very fast effective impact speed. A fascinating addition to the diagnostic info available.

cheers, Bill. Wed, 2015-03-18 20:43