APOD: Asteroids in the Distance (2011 Mar 06)

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APOD: Asteroids in the Distance (2011 Mar 06)

Post by APOD Robot » Sun Mar 06, 2011 5:15 am

Image Asteroids in the Distance

Explanation: Rocks from space hit Earth every day. The larger the rock, though, the less often Earth is struck. Many kilograms of space dust pitter to Earth daily. Larger bits appear initially as a bright meteor. Baseball-sized rocks and ice-balls streak through our atmosphere daily, most evaporating quickly to nothing. Significant threats do exist for rocks near 100 meters in diameter, which strike the Earth roughly every 1000 years. An object this size could cause significant tsunamis were it to strike an ocean, potentially devastating even distant shores. A collision with a massive asteroid, over 1 km across, is more rare, occurring typically millions of years apart, but could have truly global consequences. Many asteroids remain undiscovered. In fact, one was discovered in 1998 as the long blue streak in the above archival image taken by the Hubble Space Telescope. In 2002 June, the small 100-meter asteroid 2002 MN was discovered only after it whizzed by the Earth, passing well within the orbit of the Moon. 2002 MN passed closer than any asteroid since 1994 XM1, but not as close as 2004 MN4 will pass in 2029. A collision with a large asteroid would not affect Earth's orbit so much as raise dust that would affect Earth's climate. One likely result is a global extinction of many species of life, possibly dwarfing the ongoing extinction occurring now.

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Re: APOD: Asteroids in the Distance (2011 Mar 06)

Post by dp » Sun Mar 06, 2011 8:11 am

I hope this site won't go further down this politicized global warming path. It would be such a disappointment to drop yet another interesting science page because of serial CAGW injection that is so out of context and scope.

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Re: APOD: Asteroids in the Distance (2011 Mar 06)

Post by neufer » Sun Mar 06, 2011 12:55 pm

dp wrote:
I hope this site won't go further down this politicized global warming path. It would be such a disappointment to drop yet another interesting science page because of serial CAGW injection that is so out of context and scope.
INCOMING :!:

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Re: APOD: Asteroids in the Distance (2011 Mar 06)

Post by Chris Peterson » Sun Mar 06, 2011 3:25 pm

dp wrote:I hope this site won't go further down this politicized global warming path. It would be such a disappointment to drop yet another interesting science page because of serial CAGW injection that is so out of context and scope.
If you don't recognize global warming for what it is, why would you be looking at any science pages in the first place?
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Re: APOD: Asteroids in the Distance (2011 Mar 06)

Post by moonstruck » Sun Mar 06, 2011 3:30 pm

Wow, that's scary. I guess the ones coming straight at us won't leave a trail. They'll just get bigger. Ugh!

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Re: APOD: Asteroids in the Distance (2011 Mar 06)

Post by Guest » Sun Mar 06, 2011 3:43 pm

dp wrote:I hope this site won't go further down this politicized global warming path. It would be such a disappointment to drop yet another interesting science page because of serial CAGW injection that is so out of context and scope.
Some of us will miss you, others not. We thought we were here to look at the picture, now we know you were trolling for political affirmation. Best move on.

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Re: APOD: Asteroids in the Distance (2011 Mar 06)

Post by just a thought » Sun Mar 06, 2011 3:49 pm

moonstruck wrote:Wow, that's scary. I guess the ones coming straight at us won't leave a trail. They'll just get bigger. Ugh!
I think the ones coming straight at us will actually not hit us as we are not stationary. The ones that hit earth do so because they are aimed where we will be in the future not where we are now.

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Re: APOD: Asteroids in the Distance (2011 Mar 06)

Post by BobStein-VisiBone » Sun Mar 06, 2011 3:57 pm

Blue lines and yellow lines - anyone else wondering what they mean? Are they innies and outies?

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Re: APOD: Asteroids in the Distance (2011 Mar 06)

Post by neufer » Sun Mar 06, 2011 4:08 pm

moonstruck wrote:
Wow, that's scary. I guess the ones coming straight at us won't leave a trail. They'll just get bigger. Ugh!
http://en.wikipedia.org/wiki/Gastornis wrote: <<Gastornis (formerly known as Diatryma), is an extinct genus of large flightless bird that lived during the late Paleocene and Eocene epochs of the Cenozoic. It was named in 1855, after Gaston Planté, who had discovered the first fossils in Argile Plastique formation deposits at Meudon near Paris (France). In the 1870s, the famous American paleontologist Edward Drinker Cope discovered another, more complete set of fossils in North America, and named them Diatryma (from Greek διάτρημα meaning "canoe").

Gastornis parisiensis measured on average 1.75 metres tall, but large individuals grew up to 2 metres tall. The Gastornis had a remarkably huge beak with a slightly hooked top, which was taken as evidence suggesting that it was carnivorous. At its time, the environment in which Gastornis lived in had large portions of dense forest and a moist to semiarid subtropical or even tropical climate. North America and Europe were still rather close, and especially since Greenland probably was covered with lush woodland and grassland then, only narrow straits of a few 100 km at most would have blocked entirely landbound dispersal of the Gastornis ancestors. While there were large contiguous areas of land in their North American range after the Western Interior Seaway had receded, their European range was an archipelago due to the Alpide orogeny and the high sea levels of the Paleocene-Eocene Thermal Maximum.

Classically, Gastornis has been depicted as predatory. However, with the size of Gastornis legs, the bird would have had to have been more agile to catch fast-moving prey than the fossils suggest it to have been. Consequently, it has been suspected that Gastornis was an ambush hunter and/or used pack hunting techniques to pursue or ambush prey; if Gastornis was a predator, it would have certainly needed some other means of hunting prey through the dense forest.

Similar gigantic birds of the Cenozoic were the South American terror birds (phorusrhacids) and the Australian mihirungs (Dromornithidae). The former were certainly carnivorous, and the latter are suspected of being predators, too. Gastornis were among the largest, if not the largest birds alive during the Paleogene. They had few natural enemies and serious competitors apart from other Gastornis or then-rare large mammals, such as the predatory bear-like Arctocyon of Europe. If these huge birds were active hunters, they must have been important apex predators that dominated the forest ecosystems of North America and Europe until the middle Eocene. The mid-Eocene saw the rise of large creodont and mesonychid predators to ecological prominence in Eurasia and North America; the appearance of these new predators coincides with the decline of Gastornis and its relatives. This was possibly due to an increased tendency of mammalian predators to hunt together in packs. The fact that no birds appear to have ever weighed much more than half a metric ton suggests that they were restricted in their ability to evolve to larger and larger sizes, and thus in their ability to out-evolve apex predators by sheer bulk as mammals are often able to do.>>
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Re: APOD: Asteroids in the Distance (2011 Mar 06)

Post by neufer » Sun Mar 06, 2011 4:19 pm

BobStein-VisiBone wrote:
Blue lines and yellow lines - anyone else wondering what they mean? Are they innies and outies?
There is only ONE asteroid trail: the curved blue one.

"Numerous orange and blue specks...were created by cosmic rays that struck the camera's detector."
http://hubblesite.org/newscenter/archive/releases/1998/10/image/a/ wrote: Astronomers Karl Stapelfeldt and Robin Evans have tracked down about 100 small asteroids by hunting through more than 28,000 archival images taken by the Hubble Space Telescope's Wide Field and Planetary Camera 2. Here is a sample of what they have found: four archival images that show the curved trails left by asteroids.

[Top left]: Hubble captured a bright asteroid, with a visual magnitude of 18.7, roaming in the constellation Centaurus. Background stars are shown in white, while the asteroid trail is depicted in blue at top center. The trail has a length of 19 arc seconds. This asteroid has a diameter of one and one-quarter miles (2 kilometers), and was located 87 million miles from Earth and 156 million miles from the Sun. Numerous orange and blue specks in this image and the following two images were created by cosmic rays, energetic subatomic particles that struck the camera's detector.

[Top right]: Here is an asteroid with a visual magnitude of 21.8 passing a galaxy in the constellation Leo. The trail is seen in two consecutive exposures, the first shown in blue and the second in red. This asteroid has a diameter of half a mile (0.8 kilometers), and was located 188 million miles from Earth and 233 million miles from the Sun.

[Lower left]: This asteroid in the constellation Taurus has a visual magnitude of 23, and is one of the faintest seen so far in the Hubble archive. It moves from upper right to lower left in two consecutive exposures; the first trail is shown in blue and the second in red. Because of the asteroid's relatively straight trail, astronomers could not accurately determine its distance. The estimated diameter is half a mile (0.8 kilometers) at an Earth distance of 205 million miles and a Sun distance of 298 million miles.

[Lower right]: This is a broken asteroid trail crossing the outer regions of galaxy NGC 4548 in Coma Berenices. Five trail segments (shown in white) were extracted from individual exposures and added to a cleaned color image of the galaxy. The asteroid enters the image at top center and moves down toward the lower left. Large gaps in the trail occur because the telescope is orbiting the Earth and cannot continuously observe the galaxy. This asteroid has a visual magnitude of 20.8, a diameter of one mile (1.6 kilometers), and was seen at a distance of 254 million miles from Earth and 292 million miles from the Sun.>>
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Re: APOD: Asteroids in the Distance (2011 Mar 06)

Post by peter_from_nyc » Sun Mar 06, 2011 4:24 pm

How big was the one with the "blue streak"?
In fact, one was discovered in 1998 as the long blue streak in the above archival image taken by the Hubble Space Telescope
Also, it seems to curve, suggesting an ellipse as per Newton's laws. What are its focal points? (What is it orbiting? -- the sun?)

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Talking up a "blue streak"

Post by neufer » Sun Mar 06, 2011 4:34 pm

peter_from_nyc wrote:
How big was the one with the "blue streak"?
"This asteroid has a diameter of 2 kilometers (i.e., a little bigger than Dactyl),
and was located 87 million miles from Earth and 156 million miles from the Sun."
The trail has a length of 19 arc seconds.
peter_from_nyc wrote:
Also, it seems to curve, suggesting an ellipse as per Newton's laws. What are its focal points? (What is it orbiting? -- the sun?)
The Hubble Space Telescope around the earth
and the earth itself (relative to the asteroid)
combine to make a sinusoidal path.
............................................
For our missing Ann (who visits but no longer posts :( ):
http://www.word-detective.com/2009/02/22/blue-streak/ wrote:
Dear Word Detective: I was wondering if you could help me find the origin of the phrase “blue streak” as in “talk a blue streak” or “curse a blue streak.” The only thing I could find was that it might have something to do with lightning. — Eric.

<<Good question, but before we begin, I would strongly advise against having anything to do with lightning, and I speak from personal experience. Three years ago this month I had a close encounter with ball lightning (yes, it most certainly does exist), and some people say I haven’t been quite right ever since. Apart from a tendency to cry when I eat oatmeal and bark when I’m angry, however, I can’t imagine what they’re talking about. Anyway, lightning is definitely nasty stuff.

Onward. Human beings have identified a wide spectrum of colors (and catalog copywriters are constantly inventing new ones), but when it comes to popular figures of speech, “blue” takes the prize for both number and variety of senses. We speak, for example, of sadness or depression as “the blues,” although no one has ever come up with a convincing explanation why. “Blues” music does often center on depressing “blue” subjects (lover left, dog died, etc.), but that “blue” may actually be a reference to the genre’s use of “blue notes,” halfway between proper scale notes. Elsewhere, “blue blood” is said to signify royalty or high social class, but was originally just a reference to very light skin, which made the oxygen-rich blood in one’s veins visible under the skin. The opposite of the blue-blooded idle rich are, of course, “blue-collar” workers, so-called for the denim shirts that once were standard factory wear.

Some towns in the US still enforce “blue laws” forbidding or restricting certain activities on Sundays, but the origin of the term has been lost in the mists of time along with the Puritans who concocted the laws. And, at the other end of the spectrum, we have the slightly antiquated (but equally mysterious) adjective “blue” meaning “obscene,” which dates to the 1820s (and thus predates “blue movies” by a century). It’s possible, however, that “blue” in the “porn” sense arose from the term “blue laws” being generalized to mean any kind of censorious legislation.

Meanwhile, as the stock exchange tumbles and staid “blue chip” stocks take a beating, it’s appropriate to note that “blue chip” meaning “top rank, best” comes from the highest denomination chips in the very un-staid game of poker, which are traditionally blue.

All of which brings us to “blue streak,” which means “with great intensity or speed” and originated in the US in the early 18th century. In all likelihood, the term did arise by analogy to the speed and force of a bolt of lightning, especially in “talk a blue streak,” meaning to speak rapidly and excitedly. The “blue” in “curse a blue streak” probably also invokes “blue” in the sense of “obscene.” A similar phrase, “blue blazes” (“And the two Jacobs swore like blue blazes agin him,”1858), was originally a reference to the fires of Hell, where it is said that brimstone burns with a pale blue flame.>>
Last edited by neufer on Sun Mar 06, 2011 4:50 pm, edited 1 time in total.
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Re: APOD: Asteroids in the Distance (2011 Mar 06)

Post by Chris Peterson » Sun Mar 06, 2011 4:41 pm

peter_from_nyc wrote:How big was the one with the "blue streak"?
It was about 2km in diameter.
Also, it seems to curve, suggesting an ellipse as per Newton's laws. What are its focal points? (What is it orbiting? -- the sun?)
Yes, virtually all asteroids are orbiting the Sun, which is therefore at one of the foci. (Asteroids are occasionally captured by planets- there are known cases for the Earth and for Jupiter, but these are extremely rare cases.)
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Re: APOD: Asteroids in the Distance (2011 Mar 06)

Post by Chris Peterson » Sun Mar 06, 2011 4:46 pm

BobStein-VisiBone wrote:Blue lines and yellow lines - anyone else wondering what they mean? Are they innies and outies?
These images are captured through different filters in successive exposures. Uncalibrated images are full of cosmic ray hits and other anomalies. These are events that happen only in single exposures, so when the frames are combined to produce color images, all the transient stuff (including some or all of the asteroid path) is shown only in a single color, not a properly synthetic color.
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Re: APOD: Asteroids in the Distance (2011 Mar 06)

Post by nstahl » Sun Mar 06, 2011 5:04 pm

Chris wrote:These images are captured through different filters in successive exposures. Uncalibrated images are full of cosmic ray hits and other anomalies. These are events that happen only in single exposures, so when the frames are combined to produce color images, all the transient stuff (including some or all of the asteroid path) is shown only in a single color, not a properly synthetic color.
Thank you! So this image, and presumably the others in the Hubble Archive that have been used to find asteroids, are actually a combination of successive shots, with each shot a long exposure. Any idea how long the exposures are and how far apart in time those successive shots are? And I take it the streaks are pretty much as they were on the Hubble shot? Maybe only jazzed up a little for more visibility?

And I, like others here, would rather have global warming discussed as appropriate rather than hiding our heads.

I'd have asked this earlier but I had to sign back in and to do that I had to find my pw. Happily, I did.
Last edited by nstahl on Sun Mar 06, 2011 5:08 pm, edited 1 time in total.

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Re: APOD: Asteroids in the Distance (2011 Mar 06)

Post by owlice » Sun Mar 06, 2011 5:07 pm

As always, great pic, text, and links, and an extra wow! for one of the videos.
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Here's a nice knock-down argument for you!

Post by neufer » Sun Mar 06, 2011 6:57 pm

dp wrote:I hope this site won't go further down this politicized global warming path. It would be such a disappointment to drop yet another interesting science page because of serial CAGW injection that is so out of context and scope.
I have NO idea what this particular APOD has to do with global warming
(; not that there's anything wrong with an APOD discussing global warming).
  • `And only one [day] for birthday presents, you know. There's glory for you!'

    `I don't know what you mean by "glory,"' Alice said.

    Humpty Dumpty smiled contemptuously. `Of course you don't -- till I tell you. I meant "there's a nice knock-down argument for you!"'

    `But "glory" doesn't mean "a nice knock-down argument,"' Alice objected.

    `When I use a word,' Humpty Dumpty said in rather a scornful tone, `it means just what I choose it to mean -- neither more nor less.'

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Re: Here's a nice knock-down argument for you!

Post by bystander » Sun Mar 06, 2011 7:06 pm

neufer wrote:I have NO idea what this particular APOD has to do with global warming
(; not that there's anything wrong with an APOD discussing global warming).]
APOD Robot wrote:One likely result is a global extinction of many species of life, possibly dwarfing the ongoing extinction occurring now.
Know the quiet place within your heart and touch the rainbow of possibility; be
alive to the gentle breeze of communication, and please stop being such a jerk.
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Re: APOD: Asteroids in the Distance (2011 Mar 06)

Post by Chris Peterson » Sun Mar 06, 2011 7:21 pm

nstahl wrote:Thank you! So this image, and presumably the others in the Hubble Archive that have been used to find asteroids, are actually a combination of successive shots, with each shot a long exposure. Any idea how long the exposures are and how far apart in time those successive shots are?
The maximum exposure time of a single frame is limited by where in the sky an object is. Because the HST orbits the Earth once every 98 minutes or so, and is not allowed to point too close to Earth, many objects have maximum single-frame exposure times of around an hour. Objects at high declinations may be visible continuously without the Earth interfering. Some HST images are collected over months, some are collected in a single session or a series of closely spaced sessions.
And I take it the streaks are pretty much as they were on the Hubble shot? Maybe only jazzed up a little for more visibility?
These frames may or may not have been calibrated. They look clean enough that I think it likely they have at least had dark frame calibration applied. Individual camera frames are normally full of cosmic ray hits. These are eliminated by median combining image stacks. However, as this asteroid appears on a single frame, there's no way to separate cosmic ray tracks from true signal.
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Re: APOD: Asteroids in the Distance (2011 Mar 06)

Post by Beyond » Sun Mar 06, 2011 7:59 pm

neufer wrote:(Predatory bear-like) Artogyon Neuendorffer
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Re: APOD: Asteroids in the Distance (2011 Mar 06)

Post by NoelC » Sun Mar 06, 2011 8:15 pm

neufer wrote: There is only ONE asteroid trail: the curved blue one.
You really sure about that? An image taken through two different filters at different times might show a moving object in two different colors, depending on how it was put together. Fixed objects - e.g., the stars - would appear less colorful. Objects in general appear more integrated into the image.

Are you thinking every last one of the small streaks are particle hits on the imager? I wonder... Some of them look a little different than most of the others.

I'm assuming the curvature in the main streak is because of the HST's orbital motion.

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Re: Here's a nice knock-down argument for you!

Post by neufer » Sun Mar 06, 2011 8:33 pm

bystander wrote:
neufer wrote:I have NO idea what this particular APOD has to do with global warming
(; not that there's anything wrong with an APOD discussing global warming).]
APOD Robot wrote:One likely result is a global extinction of many species of life, possibly dwarfing the ongoing extinction occurring now.
Global warming is unlikely to be directly responsible for any known current global extinction.
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Re: Here's a nice knock-down argument for you!

Post by bystander » Sun Mar 06, 2011 8:39 pm

neufer wrote:Global warming is unlikely to be directly responsible for any known current global extinction.
Maybe, maybe not. Many Amphibians would probably disagree.
I was just pointing out the most likely link to global warming.
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Re: APOD: Asteroids in the Distance (2011 Mar 06)

Post by nstahl » Sun Mar 06, 2011 8:49 pm

NoelC wrote:I'm assuming the curvature in the main streak is because of the HST's orbital motion.
Yes I suppose so. From one of the links I found the claim they use the curvature to get the distance, like in parallax. I still have to wonder at the look of the path; it would seem an asteroid would be dim. And for only about an hour's exposure that covered a long distance compared to the field, so it must be quite a narrow field. Or is it the fact the asteroid is so much closer than the stars that, along with the orbital path of Hubble, causes the long asteroidal path?

Do those asteroid paths really just pop out of the archival shots like that?
bystander wrote: Many Amphibians would probably disagree.
Not to mention some critters who've been living by/moving up mountain peaks and can't move any higher to stay cool.

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Re: APOD: Asteroids in the Distance (2011 Mar 06)

Post by Chris Peterson » Sun Mar 06, 2011 8:54 pm

NoelC wrote:You really sure about that? An image taken through two different filters at different times might show a moving object in two different colors, depending on how it was put together. Fixed objects - e.g., the stars, would appear less colorful.

Are you thinking every last one of the small streaks are particle hits on the imager? I wonder... Some of them look a little different than most of the others.
I think it is a fair assumption that all the other streaks are cosmic ray hits. They certainly look like them. An asteroid captured over multiple frames assigned to different color channels will look like this:

Image
I'm assuming the curvature in the main streak is because of the HST's orbital motion.
I think so. I've imaged hundreds hundreds of asteroids, and they always appear as straight lines over reasonable exposure times.
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