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Comets


Comet 2

New Comet: C/2014 W2 (PANSTARRS)

CBET nr. 4019, issued on 2014, November 21, announces the discovery of a comet (magnitude ~18.7) by PANSTARRS survey in four w-band CCD exposures taken with the 1.8-m Pan-STARRS1 telescope at Haleakala on Nov. 17. The new comet has been designated C/2014 W2 (PANSTARRS).

We performed follow-up measurements of this object, while it was still on the neocp. Stacking of 10 unfiltered exposures, 120-sec each, obtained remotely on 2014, November 18.9 from I89 (iTelescope network - Nerpio) through a 0.43-m f/6.8 reflector + CCD, shows that this object is a comet: diffuse coma about 6" in diameter.

Our confirmation image (click on it for a bigger version)
Comet C/2014 W2
© Remanzacco Observatory
M.P.E.C. 2014-W55 (including pre-discovery Catalina Sky Survey observations, identified by T. Spahr, on Oct. 26.3, when the comet was at mag 17.7-18.0, and on Nov. 16.3 at mag 17.3-17.5) assigns the following elliptical orbital elements to comet C/2014 W2: T 2016 Mar. 19.554; e= 0.95; Peri. = 85.90; q = 2.67; Incl.= 81.04
Fireball

NASA map downplays sharp rise in meteor fireball impacts over last 20 years

© NASA/JPL
NASA's Near Earth Object (NEO) Program published a diagram a few days ago, showing 556 mapped comet/asteroid fragment impacts on Earth over the last 20 years (see above). NASA says it's based on data gathered from 1994-2013 on small asteroids impacting Earth's atmosphere to create 'fireballs', adding that "the sizes of yellow dots (daytime impacts) and blue dots (nighttime impacts) are proportional to the optical radiated energy of impacts measured in billions of Joules (GJ) of energy, and show the location of impacts from objects about 1 meter (3 feet) to almost 20 meters (60 feet) in size."

Note the random distribution of impacts around the globe. But note also what the map and accompanying NASA report do not indicate: the year-on-year distribution of those impact events over that 20-year period. This omission enables them to give the following misleading subheading to their report:
It happens all the time: small asteroids impact Earth's atmosphere
By not providing a year-on-year breakdown of the impacts, and by including their rather banal headline, NASA leaves us to assume that these events were more or less evenly distributed over those 20 years - on average, 27 fireball events of note in 2013 (556 total events/20 years). But we have serious doubts about this.

We know from the American Meteor Society that there were nearly 3,500 observed events in 2013 alone - and just in the US. Check out the data for yourself: browse through the AMS Events database. Select for events in 2013 with both 'sound' and 'fragmentation' reported. Note how many of last year's 184 US fireball events, that were large enough to be both seen breaking up and heard exploding, were witnessed from multiple US states. Now go back to the NASA world fireball map from 1994-2013. Assuming its random global distribution is accurate, we can try a little exercise in extrapolation to get a figure for significant fireball events globally in 2013.
Comet 2

Eight billion asteroids in the Oort cloud?

1996 PW
© JPL/Horizons
When discovered, the object 1996 PW looked like an asteroid but had the elongated, 5,900-year-long orbit of an Oort Cloud comet.
When a telescope atop Hawaii's Haleakala swept up a fast-moving object in August 1996, astronomers didn't know what to make of it. Designated 1996 PW, the little interloper had the highly elongated orbit of a comet that had ventured inward from the Oort Cloud, at the solar system's outermost fringe.

But it had no tail or coma - visually and spectroscopically, it looked like an asteroid.

At the time, dynamicists Paul Weissman (Jet Propulsion Laboratory) and Hal Levison (Southwest Research Institute) proposed that 1996 PW might actually be a rare hybrid: an asteroid from the Oort Cloud. Their suggestion ran completely counter to the consensus notion that only comets existed in that vast, distant reservoir. But Weissman and Levison had run the numbers: they calculated that, along with a trillion or so comets, roughly 8 billion asteroids could have been flung out into the Oort Cloud by close planetary encounters early in solar-system history.

When other researchers suggested that 1996 PW was probably just an "extinct" comet, having depleted the volatile ices that create a coma or tail, the notion of asteroids in the Oort Cloud got shelved - but not completely forgotten.

Comment:

Electric Universe: Tail discovered on long-known asteroid

Icy asteroids: Resident asteroids sprout comet-like dust tails

Comet

Rosetta's comet sings a mysterious 'song'

Comet 67P
© ESA/Rosetta/NavCam
Through some kind of interaction in the comet's environment, 67P's weak magnetic field seems to be oscillating at low frequencies.
The Rosetta mission has detected a mysterious signal coming from Comet 67P/Churyumov-Gerasimenko.

The mission has five instruments in the Rosetta Plasma Consortium (RPC) that measure the plasma environment surrounding the comet.

Plasma is a charged gas and the RPC is tasked with understanding variations in the comet's activity, how 67P's jets of vapour and dust interacts with the solar wind and the dynamic structure of the comet's nucleus and coma.

But when recording signals in the 40-50 millihertz frequency range, the RPC scientists stumbled on a surprise - the comet was singing, they report.

Through some kind of interaction in the comet's environment, 67P's weak magnetic field seems to be oscillating at low frequencies. In an effort to better understand this unique 'song', mission scientists have increased the frequency 10,000 times to make it audible to the human ear.
Fireball 4

Warning for Earth: Comet Siding Spring's near-brush with Mars triggered 'mind blowing' meteor shower

© NASA
Comet Siding Spring's close flyby of Mars last month dumped several tons of primordial dust into the thin martian atmosphere, likely creating a brief but spectacular meteor shower with thousands of shooting stars per hour had any astronauts been there to see it, scientists said Friday.

The comet dust also posed a much more serious threat than expected to an international fleet of spacecraft in orbit around the red planet and roving about its surface. While engineers did not think the comet posed a major hazard, the orbiters were maneuvered to put them on the far side of Mars during close approach. Just in case.

As it turned out, that was a smart decision.

"After observing the effects on Mars and how the comet dust slammed into the upper atmosphere, it makes me very happy that we decided to put our spacecraft on the other side of Mars at the peak of the dust tail passage and out of harm's way," Jim Green, director of planetary science at NASA headquarters, told reporters during a teleconference. "I really believe that hiding them like that really saved them, and it gave us a fabulous opportunity to make these observations."

Comment: If NASA et al had been paying even the slightest attention to what is happening here on Earth, rather than guess-timating with their fancy gadgets what might have happened on Mars, they'd realize they have plenty of real-life exploding comet fragments and comet dust to analyze right here at home.

Check out the astonishing afterglow caused by this exploding meteor over Recife, Brazil last month:

Meteor fireball sets the sky on fire over Recife, Brazil

Comet

New fragmentation event in C/2011 J2 (LINEAR)

Starting from 2014, Sept 26.9 we are constantly monitoring comet C/2011 J2 (LINEAR) and his fragment B through a 2.0-m f/10.0 Ritchey-Chretien + CCD (La Palma-Liverpool Telescope). The video below shows an animation we made using our recent obs of this comet. Time span is 9 days (from 1 Oct. to 9 Oct). The projected velocity of the fragment is of about 0.3 arcsec/day.


While performing follow-up of component B of comet C/2011 J2 on 2014, Oct 09.9 we detected a possible new diffuse fragment located in the very near proximity of main component A.
Comet

Comet Siding Spring: Close call for Mars, wake up call for Earth?

Comet Siding Spring
© NASA,ESA, ISRO
Five orbiters from India, the European Union and the United States will nestle behind Mars as comet Siding Springs passes at a speed of 200,000 km/hr (125,000 mph). At right, Shoemaker-Levy 9 impacts on Jupiter, the Chelyabinsk Asteroid over Russia.
It was 20 years ago this past July when images of Jupiter being pummeled by a comet caught the world's attention. Comet Shoemaker-Levy 9 had flown too close to Jupiter. It was captured by the giant planet's gravity and torn into a string of beads. One by one the comet fragments impacted Jupiter - leaving blemishes on its atmosphere, each several times larger than Earth in size.

Until that event, no one had seen a comet impact a planet. Now, Mars will see a very close passage of the comet Siding Spring on October 19th. When the comet was first discovered, astronomers quickly realized that it was heading straight at Mars. In fact, it appeared it was going to be a bulls-eye hit - except for the margin of error in calculating a comet's trajectory from 1 billion kilometers (620 million miles, 7 AU) away.

It took several months of analysis for a cataclysmic impact on Mars to be ruled out. So now today, Mars faces a just a cosmic close shave. But this comet packs enough energy that an impact would have globally altered Mars surface and atmosphere.
Comet 2

Follow-up of splitting event in Comet C/2011 J2

Comet C/2011 J2
© Remanzacco Observatory
CBET 3979, issued on 2014 September 19, announced that observations of comet C/2011 J2 (LINEAR) (by F. Manzini, V. Oldani, A. Dan and R. Behrend) on Aug. 27.95, 28.85, and 30.91 UT led to the detection of a second, fainter, nuclear condensation (from now on Component B) located 0".8 east and 7".5 north of the main, brighter nuclear condensation (component A).

For more info about comet C/2011 J2 please see our May 2011 post on this blog by clicking here.

Whilst working on a long term morphology study on comet C/2012 K1 with N. Samarasinha and B. Mueller using the 2-meter Liverpool Telescope, we were alerted of the fragmentation event in comet C/2011 J2 and so diverted the telescope to this comet for a few days.
Comet

PanSTARRS K1, the comet that keeps going and going and going

Comet C/2012 K1 PanSTARRS
© Rolando Ligustri
Comet C/2012 K1 PanSTARRS photographed on September 26, 2014. Two tails are seen – a dust tail points off to the left and the gas or ion tail to the right.
Thank you K1 PanSTARRS for hanging in there! Some comets crumble and fade away. Others linger a few months and move on. But after looping across the night sky for more than a year, this one is nowhere near quitting. Matter of fact, the best is yet to come.

This new visitor from the Oort Cloud making its first passage through the inner solar system, C/2012 K1 was discovered in May 2012 by the Pan-STARRS 1 survey telescope atop Mt. Haleakala in Hawaii at magnitude 19.7. Faint! On its the inbound journey from the Oort Cloud, C/2012 K1 approached with an orbit estimated in the millions of years. Perturbed by its interactions with the planets, its new orbit has been reduced to a mere ~400,000 years. That makes the many observing opportunities PanSTARRS K1 has provided that much more appreciated. No one alive now will ever see the comet again once this performance is over.
Fireball 5

Rosetta update: Dirty snowball is "dry like hell"


The European Space Agency's Rosetta Mission to the comet 67/P may be rewriting everything astronomers thought they knew about the nature of comets. The latest high-resolution images of the comet nucleus have astonished scientists around the world, revealing a remarkably jagged, pitted, black as coal surface. It is nothing like the so-called dirty snowball or fluffy ice ball that mainstream astronomers have long envisioned. Most astonishingly, scientists have reported they have not found a single trace of water ice on the comet surface. It is, in the words of mission scientist Holger Sierks, "dry like hell."
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