Posted on 09/29/2017 9:08:12 AM PDT by Red Badger
NASA's Hubble Space Telescope has photographed the farthest active inbound comet ever seen, at a whopping distance of 1.5 billion miles from the Sun (beyond Saturn's orbit). Slightly warmed by the remote Sun, it has already begun to develop an 80,000-mile-wide fuzzy cloud of dust, called a coma, enveloping a tiny, solid nucleus of frozen gas and dust. These observations represent the earliest signs of activity ever seen from a comet entering the solar system's planetary zone for the first time.
The comet, called C/2017 K2 (PANSTARRS) or "K2", has been travelling for millions of years from its home in the frigid outer reaches of the solar system, where the temperature is about minus 440 degrees Fahrenheit. The comet's orbit indicates that it came from the Oort Cloud, a spherical region almost a light-year in diameter and thought to contain hundreds of billions of comets. Comets are the icy leftovers from the formation of the solar system 4.6 billion years ago and therefore pristine in icy composition.
"K2 is so far from the Sun and so cold, we know for sure that the activity—all the fuzzy stuff making it look like a comet—is not produced, as in other comets, by the evaporation of water ice," said lead researcher David Jewitt of the University of California, Los Angeles. "Instead, we think the activity is due to the sublimation [a solid changing directly into a gas] of super-volatiles as K2 makes its maiden entry into the solar system's planetary zone. That's why it's special. This comet is so far away and so incredibly cold that water ice there is frozen like a rock."
Based on the Hubble observations of K2's coma, Jewitt suggests that sunlight is heating frozen volatile gases - such as oxygen, nitrogen, carbon dioxide, and carbon monoxide - that coat the comet's frigid surface. These icy volatiles lift off from the comet and release dust, forming the coma. Past studies of the composition of comets near the Sun have revealed the same mixture of volatile ices.
Schematic of Comet C/2017 K2's Approach to the Solar System. Credit: NASA =======================================================================
"I think these volatiles are spread all through K2, and in the beginning billions of years ago, they were probably all through every comet presently in the Oort Cloud," Jewitt said. "But the volatiles on the surface are the ones that absorb the heat from the Sun, so, in a sense, the comet is shedding its outer skin. Most comets are discovered much closer to the Sun, near Jupiter's orbit, so by the time we see them, these surface volatiles have already been baked off. That's why I think K2 is the most primitive comet we've seen."
K2 was discovered in May 2017 by the Panoramic Survey Telescope and Rapid Response System (Pan-STARRS) in Hawaii, a survey project of NASA's Near-Earth Object Observations Program. Jewitt used Hubble's Wide Field Camera 3 at the end of June to take a closer look at the icy visitor.
Hubble's sharp "eye" revealed the extent of the coma and also helped Jewitt estimate the size of the nucleus—less than 12 miles across—though the tenuous coma is 10 Earth diameters across.
This vast coma must have formed when the comet was even farther away from the Sun. Digging through archival images, Jewitt's team uncovered views of K2 and its fuzzy coma taken in 2013 by the Canada-France-Hawaii Telescope (CFHT) in Hawaii. But the object was then so faint that no one noticed it.
"We think the comet has been continuously active for at least four years," Jewitt said. "In the CFHT data, K2 had a coma already at 2 billion miles from the Sun, when it was between the orbits of Uranus and Neptune. It was already active, and I think it has been continuously active coming in. As it approaches the Sun, it's getting warmer and warmer, and the activity is ramping up."
But, curiously, the Hubble images do not show a tail flowing from K2, which is a signature of comets. The absence of such a feature indicates that particles lifting off the comet are too large for radiation pressure from the Sun to sweep them back into a tail.
Astronomers will have plenty of time to conduct detailed studies of K2. For the next five years, the comet will continue its journey into the inner solar system before it reaches its closest approach to the Sun in 2022 just beyond Mars' orbit. "We will be able to monitor for the first time the developing activity of a comet falling in from the Oort Cloud over an extraordinary range of distances," Jewitt said. "It should become more and more active as it nears the Sun and presumably will form a tail."
Jewitt said that NASA's James Webb Space Telescope, an infrared observatory scheduled to launch in 2018, could measure the heat from the nucleus, which would give astronomers a more accurate estimate of its size.
The team's results will appear in the September 28 issue of The Astrophysical Journal Letters.
Explore further: Arecibo Observatory captures revealing images of Comet 45P/Honda-Mrkos-Pajdusakova
More information: David Jewitt et al. A Comet Active Beyond the Crystallization Zone, The Astrophysical Journal (2017). DOI: 10.3847/2041-8213/aa88b4
Journal reference: Astrophysical Journal Letters
Earth may get a piece of tail!!! OUCH
Lol
In this diagram of the inner solar system, all of the fireball orbits intersect at a single point--Earth.
Of course, else they wouldn't have been fireballs.................
We have a close call coming on October 12, 2017:
Name: 2012 TC4
Date Closest to Earth: 2017-Oct-12
Miss Distance from Earth: 0.1 Lunar Distance (roughly 24,000 miles)
Velocity: 7.6 Kilometers per second (roughly 5 miles per second)
Diameter: 16 Meters (roughly 52.5 feet)
Margin of error.... ???? I would like to know!
Note: A lunar Distance is the distance to the moon or approximately 238,900 miles
Small objects frequently collide with Earth. There is an inverse relationship between the size of the object and the frequency of such events. The lunar cratering record shows that the frequency of impacts decreases as approximately the cube of the resulting crater's diameter, which is on average proportional to the diameter of the impactor.[6] Asteroids with a 1 km (0.62 mi) diameter strike Earth every 500,000 years on average.[7] Large collisions – with 5 km (3 mi) objects – happen approximately once every twenty million years.[8] The last known impact of an object of 10 km (6 mi) or more in diameter was at the Cretaceous–Paleogene extinction event 66 million years ago.[9]
The energy released by an impactor depends on diameter, density, velocity, and angle.[8] The diameter of most near-Earth asteroids that have not been studied by radar or infrared can generally only be estimated within about a factor of 2 based on the asteroid brightness. The density is generally assumed because the diameter and mass are also generally estimates. The minimum impact velocity on Earth is 11 km/s with asteroid impacts averaging around 17 km/s.[8] The most probable impact angle is 45 degrees.[8]
Frequency of small asteroids roughly 1 to 20 meters in diameter impacting Earth's atmosphere.
WE ARE SAFE ON OCTOBER 12
Very Interesting..
If we could only direct one of these toward North Korea...
Per Wiki:
An Asteroid 20 m or (66 ft) would generate Kinetic energy of 376 kt at atmospheric entry and airburst Kinetic Energy of 230 kt at 22.4 km (73,000 ft). These happen approximately every 60 Years on average.
Note: Bombs on Japan were 15 and 20 kt
Correction:
1 LD = 384,401 km, the distance between Earth and the Moon per Spaceweather.com.
The gases aren’t boiling off, they’re being blown off ... after a long voyage, its braking ...
Lucifer’s Hammer
I read that book back in 78-79..................
So -- your
"A lunar Distance is the distance to the moon or approximately 238,900 miles"
in #9, wasn't too shabby... '-)
(H/T to my Mac's handy "Units Converter Widget"...)
The mean semi-major axis has a value of 384,402 km (238,856 mi). The time-averaged distance between Earth and Moon centers is 385,000.6 km (239,228.3 mi). The actual distance varies over the course of the orbit of the Moon, from 356,500 km (221,500 mi) at the perigee to 406,700 km (252,700 mi) at apogee, resulting in a differential range of 50,200 km (31,200 mi).
Interesting... My mind has been in a fog for a few weeks and yesterday it was hitting bottom. Dr’s could not figure it out so I went to the medical and neuroscience texts and figured it out late yesterday.
It’s amazing how a Thiamine deficiency (not alcohol related) can screw with the physical body and mind.
Corrected it, along with the related fatique, ataxia, acidosis and glucose intolerance. Bingo... now I feel energized like I am on speed and my mind is the clearest in many weeks.
I thought old age was catching up to me with fatigue, systemic infections, dizziness, brain fog, and finally losing my spacial memory which has been a lifetime strong point. While I love the Dr’s, it is best to do your own medical research.
BTW, would you mind sharing what action you took to remedy your thiamine deficiency? I'm on restricted diets for gout & type 2 diabetes -- so, I know I'm missing out on some significant nutrients. (No alcohol to complicate matters...)
I'm usually a master of directions when I am driving, especially if I have been there before. I started getting lost driving to places I've been many times...Not good. In addition, I never carried a calendar as my mind could keep track of my schedule.. I couldn't do it any more.
The dentate gyrus in the hippocampus is responsible for spatial memory. I just started reviewing the biochemistry and found that a thiamine deficiency was the most likely cause. When I went through the checklist of other symptoms (about a dozen) I was 100%.
Looking back, I was having some stomach discomfort recently and I started drinking Coca Cola to belch and feel better. I never drink sugar drinks, but started having several per day. Thiamine is used in sugar metabolism to provide components to the citric acid cycle to produce APT for energy in the body. Too much sugar screwed up my system.
Here is a link to an excellent journal article from 2012:
Journal of Clinical Medicine Research
The Impact of Thiamine Treatment in the Diabetes Mellitus
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3376872/
Thiamine acts as a coenzyme for transketolase (Tk) and for the pyruvate dehydrogenase and α-ketoglutarate dehydrogenase complexes, enzymes which play a fundamental role for intracellular glucose metabolism.
The relationship between thiamine and diabetes mellitus (DM) has been reported in the literature. Thiamine levels and thiamine-dependent enzyme activities have been reduced in DM.
Genetic studies provide opportunity to link the relationship between thiamine and DM (such as Tk, SLC19A2 gene, transcription factor Sp1, α-1-antitrypsin, and p53). Thiamine and its derivatives have been demonstrated to prevent the activation of the biochemical pathways (increased flux through the polyol pathway, formation of advanced glycation end-products, activation of protein kinase C, and increased flux through the hexosamine biosynthesis pathway) induced by hyperglycemia in DM.Thiamine definitively has a role in the diabetic endothelial vascular diseases (micro and macroangiopathy), lipid profile, retinopathy, nephropathy, cardiopathy, and neuropathy.
Thiamine and Biochemical Consequences of Hyperglycemia
Role of Thiamine in the Diabetes Mellitus
Blood Glucose and Insulin Secretion
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