Topic
Comets


Comet

Comet Finlay in bright outburst, visible in small telescopes

Comet Finlay
© J. Cerny, M. Masek, K. Honkova, J. Jurysek, J. Ebr, P. Kubanek, M. Prouza, M. Jelinek
Comet Finlay on December 16th shows a bright coma and short tail. Its sudden rise to 9th magnitude was confirmed on December 18th by Australian comet observer Paul Camilleri. The moderately condensed object is about 3 arc minutes in diameter.
Short-period comet 15P/Finlay, which had been plunking along at a dim magnitude +11, has suddenly brightened in the past couple days to +8.7, bright enough to see in 10×50 or larger binoculars. Czech comet observer Jakub Cerny and his team photographed the comet on December 16th and discovered the sudden surge. Wonderful news!

While comets generally brighten as they approach the Sun and fade as they depart, any one of them can undergo a sudden outburst in brightness. You can find Finlay right now low in the southwestern sky at nightfall near the planet Mars. While outbursts are common, astronomers still aren't certain what causes them. It's thought that sub-surface ices, warmed by the comet's approach to the Sun, expand until the pressure becomes so great they shatter the ice above, sending large fragments flying and exposing fresh new ice. Sunlight gets to work vaporizing both the newly exposed vents and aerial shrapnel. Large quantities of dust trapped in the ice are released and glow brightly in the Sun's light, causing the comet to quickly brighten.

Some comets flare up dramatically. Take 29P/Schwassmann-Wachmann. Normally a dim bulb at 17th magnitude, once or twice a year it flares to magnitude 12 and occasionally 10!
Comet 2

New Comet: P/2014 X1 (ELENIN)

CBET nr. 4034, issued on 2014, December 14, announces the discovery of a comet (magnitude ~18) by Leonid Elenin on three CCD images taken on 2014, December 12 with a 0.4-m f/3 astrograph at the ISON-NM Observatory near Mayhill, NM, USA. The new comet has been designated P/2014 X1 (ELENIN).

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, December 12.4 from H06 (iTelescope network - Mayhill) through a 0.43-m f/6.8 astrograph + CCD + f/4.5 focal reducer, under bad seeing conditions, shows that this object is slightly diffuse with FWHM about 20% - 30% wider than that of nearby field stars of similar brightness.

Our confirmation image (click on it for a bigger version)
Comet P/2014 X1 Elenin
© Remanzacco Observatory
M.P.E.C. 2014-X66 (including pre-discovery Pan-STARRS1 and Mount Lemmon observations, found by G. V. Williams in the MPC archive from September and October) assigns the following elliptical orbital elements to comet P/2014 X1: T 2015 Jan. 7.74; e= 0.71; Peri. = 34.36; q = 1.81; Incl.= 25.97

Congrats to Leonid for the discovery of his third comet!
Comet 2

Comet Lovejoy heading our way

Comet Lovejoy
© Gerald Rhemann
The new Comet Lovejoy, C/2014 Q2, as imaged on November 27th by Gerald Rhemann in Austria using a remotely operated 12-inch f/3.6 astrograph in Namibia.
A new Comet Lovejoy, designated C/2014 Q2, is heading our way out of deep space and out of the deep southern sky. It may brighten to 5th magnitude from late December through much of January as it climbs into excellent viewing position for the Northern Hemisphere, high in the dark winter night.

This is Australian amateur Terry Lovejoy's fifth comet discovery. He turned it up at 15th magnitude in Puppis last August, in search images that he took with a wide-field 8-inch scope. It hasn't moved very much since then - it's still in Puppis as of December 11th - but it's hundreds of times brighter now at visual magnitude 6.8, reports David Seargent in Australia. On the 9th "I saw it easily using a pair of 6x35 binoculars," he writes. Using a 4-inch binocular telescope at 25×, he says it was a good 8 arcminutes wide with a strong central condensation and no visible tail.

And it's picking up speed across the sky for a long northward dash.
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.
Top