Rosetta’s Comet Really “Blows Up” in Latest Images

First off: no, comet 67P/Churyumov-Gerasimenko is not about to explode or disintegrate. But as it steadily gets nearer to the Sun the comet’s jets are getting more and more active and they’re putting on quite a show for the orbiting Rosetta spacecraft! Click the image for a jeterrific hi-res version.

The images above were captured by Rosetta’s NavCam on Jan. 31 and Feb. 3 from a distance of about 28 km (17 miles). Each is a mosaic of four separate NavCam acquisitions and they have been adjusted and tinted in Photoshop by yours truly to further enhance the jets’ visibility. (You can view the original image mosaics and source frames here and here.)

These dramatic views are just a hint at what’s in store; 67P’s activity will only be increasing in the coming weeks and months and, this weekend, Rosetta will be swooping down for an extreme close pass over its surface!

Detail of 67P from the Feb. 3 NavCam image
Detail of 67P from the Feb. 3 NavCam image

This Saturday, Feb. 14, Rosetta will be performing a very close pass of the comet’s nucleus, soaring over the Imhotep region at an altitude of only 6 km (3.7 miles) at 12:41 UTC. This will allow the spacecraft to closely image the comet’s surface, as well as investigate the behavior of its jets and how they interact with its developing coma.

“The upcoming close flyby will allow unique scientific observations, providing us with high-resolution measurements of the surface over a range of wavelengths and giving us the opportunity to sample – taste or sniff – the very innermost parts of the comet’s atmosphere,” said Rosetta project scientist Matt Taylor.

Read more about Rosetta’s Valentine’s Day close pass here and watch an animation of how it will be executed below.

Source: ESA

UPDATE: Here’s an image of 67P captured by Rosetta on Feb. 6 from a distance of 124 km (77 miles) as it moved into a higher orbit in preparation of its upcoming close pass. It’s the first single-frame image of the comet since leaving bound orbits.

The image has been processed to add a contrasting tint and enhance jet activity. See the original image here.

Single-frame NavCam image of comet 67P/C-G imaged on Feb. 6, 2015. Credits: ESA/Rosetta/NAVCAM – CC BY-SA IGO 3.0. Edited by Jason Major.
Single-frame NavCam image of comet 67P/C-G imaged on Feb. 6, 2015. Credits: ESA/Rosetta/NAVCAM – CC BY-SA IGO 3.0. Edited by Jason Major.

Rosetta to Snuggle Up to Comet 67P for Closest Encounter Yet

Who doesn’t like to snuggle up with their Valentine on Valentine’s Day? Rosetta will practically whisper sweet nothings into 67P’s ear on February 14 when it swings just 3.7 miles (6 km) above its surface, its closest encounter yet.

Rosetta had been orbiting the comet at a distance of some  16 miles (26 km) but beginning yesterday, mission controllers used the spacecraft’s thrusters to change its orbit in preparation for the close flyby.  First, Rosetta will move out to a distance of roughly 87 miles (140 km) from the comet this Saturday before swooping in for the close encounter at 6:41 a.m. CST on Feb. 14. Closest approach happens over the comet’s larger lobe, above the Imhotep region.

The relative position of Rosetta with Comet 67P/Churyumov–Gerasimenko at the moment of closest approach this Valentine's Day when the spacecraft will pass just 3.7 miles (6 km) above the comet’s large lobe. Credit: ESA/C.Carreau
The relative position of Rosetta with Comet 67P/Churyumov–Gerasimenko at the moment of closest approach this Valentine’s Day when the spacecraft will pass just 3.7 miles (6 km) above the comet’s large lobe. Credit: ESA/C.Carreau with additions by the author

The close encounter will provide opportunities for Rosetta’s science instruments to photograph 67P’s surface at high resolution across a range of wavelengths as well as get a close sniff of what’s inside its innermost coma or developing atmosphere. Scientists will also be looking closely at the outflowing gas and dust to see how it evolves during transport from the comet’s interior to the coma and tail.

As Rosetta swoops by its view of the comet will continuously change. Instruments will collect data on how 67P’s dust grains reflect light across a variety of orbital perspectives – from shadowless lighting with the Sun at the orbiter’s back to slanted lighting angles –  to learn more about its properties.

The Imhotep region of comet 67P features a large, relatively smooth region. Rosetta will make high resolutions of Imhotep during its close flyby. Credit: ESA/Rosetta/Navcam
The Imhotep region of comet 67P features a large, relatively smooth region and a smattering of large boulders. Rosetta will make high resolutions of Imhotep during its close flyby. Credit: ESA/Rosetta/Navcam

“After this close flyby, a new phase will begin, when Rosetta will execute sets of flybys past the comet at a range of distances, between about 15 km (9 miles) and 100 km (62 miles),” said Sylvain Lodiot, ESA’s spacecraft operations manager.

During some of the close flybys, Rosetta trajectory will be almost in step with the comet’s rotation, allowing the instruments to monitor a single point on the surface in great detail as it passes by.


Helpful animation of how ESA mission controllers are changing Rosetta’s orbit to ready the probe for the Valentine’s Day flyby.

Perihelion, when the comet arcs closest to the Sun at a distance of 115.6 million miles (186 million km), occurs on August 13. Activity should be reaching its peak around that time. Beginning one month before, the Rosetta team will identify and closely examine one of the comet’s jets in wickedly rich detail.

“We hope to target one of these regions for a fly-through, to really get a taste of the outflow of the comet,” said Matt Taylor, ESA’s Rosetta project scientist.

Yum, yum. Can’t wait for that restaurant review!

Where to Look for Comet Lovejoy Until it Fades from Sight

I hate to admit it, but our dear comet is fading. Only a little though. As Comet Q2 Lovejoy wends its way from Earth toward perihelion and beyond, it will slowly dim and diminish. With an orbital period of approximately 8,000 years it has a long journey ahead. Down here on Earth, we continue to look up every clear night hoping for yet another look at what’s been a wonderful comet. 

Comet Lovejoy and the Pleiades on January 19, 2015. Credit: Joseph Brimacombe
Comet Lovejoy and the Pleiades on January 19, 2015. Credit: Joseph Brimacombe

Despite its inevitable departure I encourage you to continue following Comet Lovejoy. It’s not often a comet vaults to naked eye brightness, and this one should remain visible without optical aid through mid-February.

Like a human celebrity, Lovejoy’s been the focus of attention from beginners and professionals alike using everything from cheap cellphone cameras to high-end telescopes to capture its magic. Who can get enough of that wildly fluctuating ion tail and greeny-blue coma?

Comet Q2 Lovejoy continues tracking north-northwest now through March. This chart shows the comet's position at 7 p.m. (CST) every 5 nights through March 5. Stars shown to magnitude +6. Created with Chris Marriott's SkyMap software
Comet Q2 Lovejoy continues tracking north-northwest now through March. This chart shows the comet’s position at 7 p.m. (CST) every 5 nights through March 5. Stars shown to magnitude +6. Click to enlarge. Created with Chris Marriott’s SkyMap software

The comet continues moving northward all winter long, sliding through  the diminutive constellations Aries and Triangulum, across Andromeda and into Cassiopeia, fading as she goes. You can use the map above and binoculars to help you follow it. I like to create lines and triangles using bright stars and deep sky objects to direct me to the comet.

Deep image of Comet Lovejoy taken with a Canon 6D with 50mm f/1.4 lens at f/2. 10  exposure of 30 secs at ISO3200 stacked. The tail, though faint, extends for possibly 18 degrees in this amazing image. Credit: Ian Sharp
Deep image of Comet Lovejoy taken with a Canon 6D with 50mm f/1.4 lens at f/2. Ten exposures of 30 secs at ISO3200 were stacked to create the final photo. The tail extends for possibly 18 degrees in this amazing image. The Pleiades are at top right; Hyades at bottom center. Credit: Ian Sharp

Tonight for instance, Lovejoy one fist held at arm’s length due west of the Pleiades. On the 29th, it’s on a line from Beta Persei (Algol) to Beta Trianguli. On February 3rd, it pulls right up alongside the colorful double star Gamma Andromedae, also called Almach, and on the 8th forms one of the apexes of an equilateral triangle with the two Betas. You get the idea.

The tail rays that show so clearly in photographs as in this image made on January 16th require dark skies and 8-inch or larger telescope to see visually. They're very low contrast. Credit: Greg Redfern
The tail rays that show so clearly in photographs as in this image made on January 16th require dark skies and an 8-inch or larger telescope to see visually. They’re very low contrast. Credit: Greg Redfern

The waxing moon will interfere with viewing beginning next weekend and render the comet nil with the naked eye, you’ll still be able to track it in binoculars during that time. Dark skies return around Feb. 7.

Comet Lovejoy captured from the Dark Sky Alqueva Reserve, Portugal on Jan. 11th by Miguel Claro

Delicate streamers show in Comet Lovejoy's ion tail in this photo from January 13th. Credit: Bernhard Hubl
Delicate streamers show in Comet Lovejoy’s ion tail in this photo from January 13th. Credit: Bernhard Hubl

How to Find and Make the Most of Comet Lovejoy

Comet Q2 Lovejoy passed closest to Earth on January 7th and has been putting on a great show this past week. Glowing at magnitude +4 with a bluish coma nearly as big as the Full Moon, the comet’s easy to see with the naked eye from the right location if you know exactly where to look. I wish I could say just tilt your head back and look up and bam! there it would be, but it’ll take a little more effort than that. But just a little, I promise. 

Comet Lovejoy and its spectacular "lively" ion tail photographed on January 8th by Nick Howes at Tzec Muan Network at Siding Spring Australia
Comet Lovejoy and its spectacular “lively” ion tail photographed on January 8th by Nick Howes at Tzec Muan Network at Siding Spring Australia

Last night, under a dark rural sky, once I spotted the comet and noticed its position in relation to nearby bright stars, I could look up and see it anytime. Finding anything other than the Moon or a bright planet in the night sky often requires a good map. I normally create a star-chart style map but thought, why not make a photographic version? So last night I snapped a few guided images of Lovejoy as it glimmered in the wilds of southern Taurus and then cloned the comet’s nightly position through onto the image. Maybe you’ll find this useful, maybe not. If not, the regular map is also included.

Comet Lovejoy position is shown for each night tonight through January 23rd. The comet should remain in the 4-5 magnitude range throughout. Click for a larger map you can print out and use outdoors. Click to enlarge and print for use outdoors. Source: Chris Marriott’s SkyMap software
Comet Lovejoy’s position is shown for each night tonight through January 23rd. The comet should remain in the 4-5 magnitude range throughout. Lovejoy is currently high in the southeastern sky at nightfall and crosses the meridian due south around 9 o’clock local time. Click for a larger map you can print out and use outdoors. Source: Chris Marriott’s SkyMap software

To see Comet Lovejoy with the naked eye you’ll need reasonably dark skies. It should be faintly visible from outer ring suburbs, but country skies will guarantee a sighting. I’ve been using bright stars in Orion and Taurus to guide binoculars – and then my eye – to the comet. Pick a couple bright stars like Aldebaran and Betelgeuse and extend a line from each to form a triangle with Lovejoy at one of the corners. If you then point binoculars at that spot in the sky, the comet should pop out. If you don’t find it immediately, sweep around the position a bit.  After you find it, lower the binoculars and try to spot it with the naked eye.

Comet Lovejoy last night January 9th around 8 p.m. (CST) shows a bright coma and faint ~1.5-degree-long
Comet Lovejoy last night January 9th around 8 p.m. (CST) shows a bright coma and faint ~1.5-degree-long tail. This photo, made with a 200mm lens, gives a good idea of what the comet looks like in 50mm binoculars. Details: f/2.8, ISO 800, 2-minute exposure. Credit: Bob King

This week, as Lovejoy continues trekking north, you can use bright orangey Aldebaran in Taurus and the Pleiades, also called the Seven Sisters star cluster, to “triangulate” your way to the comet. Look for a glowing fuzzball. In 10×50 and 8×40 binoculars, it’s obviously different from a star — all puffed up with a brighter center. The 50mm glass even shows a hint of the coma’s blue color caused by carbon molecules fluorescing in ultraviolet sunlight and a faint, streak-like tail extending to the northeast. With the naked eye, at first you might think it’s just a dim star; closer scrutiny reveals the star has a hazy appearance, pegging it as a comet.

Comet Lovejoy sketches from last night made using a 15-inch telescope. The coma is big - almost a half-degree across. The drawing shows the bright nuclear region and tiny "false nucleus". At right, a suspected plume extends to the southwest of the false nucleus. Color is how the comet really looks in the telescope. Credit: Bob King
Comet Lovejoy sketches from last night made using a 15-inch telescope. The coma is big – almost a half-degree across. The drawing shows the bright nuclear region and tiny “false nucleus”. At right, a suspected plume extends to the southwest of the false nucleus. Color is how the comet really looks in the telescope. South is up. Credit: Bob King

Through a telescope the coma is a HUGE pale blue tiki lamp of a thing with a small, much brighter nuclear region. The rays of the ion tail, so beautifully shown in photographs, are indistinct but visible with patience and a moderate-sized telescope under dark skies. At low magnification, the nucleus – the false nucleus actually, since the real comet nucleus is hidden by a shroud of dust and gas – looks like a misty star of about magnitude +9. On close inspection at high magnification (250x and up), you penetrate more deeply into the nuclear zone and the star-like center shrinks and dims to around magnitude +13.

Fascinating plumes of dust recorded by Gianluca Masi on January 6th. South is up, west to the left. Credit: Gianluca Masi
Fascinating plumes of dust recorded by Gianluca Masi on January 6th. South is up, west to the left. Credit: Gianluca Masi

If the seeing is good and comet active, high magnification will often reveal jets or fans of dust in the sunward direction, in this case west of nucleus. I’ve been studying the comet the past couple nights and am almost convinced I can see a short, very low contrast plume poking to the south of center. Generally, plumes and jets are subtle, low-contrast features. Challenging? Yes, but with Lovejoy as close as it’s going to get, now’s the time to seek them.

In this photo taken January 8th, the comet's tail is caught in the act of separated from the head or coma. Magnetic fields embedded in the stream of particles from the Sun occasionally reconnect on the rear side of a comet and pinch off its tail. Credit: Rolando Ligustri
In this photo taken January 8th, the comet’s tail is caught in the act of separated from the head or coma. Magnetic fields embedded in the stream of particles from the Sun occasionally reconnect on the rear side of a comet and pinch off its tail. A new one quickly grows to replace the old. Credit: Rolando Ligustri

Just before Christmas, fluctuations in the solar wind snapped off Comet Lovejoy’s tail. Guess what? It happened again on January 8th as recorded in dramatic fashion by astrophotographer Rolando Ligustri. An ion or gas tail like the one in the photo forms when cometary gases, primarily carbon monoxide, are ionized by solar radiation and lose an electron to become positively charged. Once “electrified”, they can be twisted, kinked and even snapped off by magnetic fields embedded in the Sun’s particle wind.

Of course, the comet didn’t miss a breath but grew another tail immediately. Look closely at the photo and you see another faint streak of light pointing beyond the coma below and left of the bright nuclear region. This may be Lovejoy’s dust tail. Most comets sport both types of tails – gas and dust – since they release both materials as the Sun heats and vaporizes their ices.

Lovejoy’s been a thrill to watch because it’s doing all the cool stuff that makes them so fun to follow. Gianluca Masi, an Italian astrophysicist and lover of all things cometary, will offer a live feed of the comet on Monday January 12th starting at 1 p.m. CST (7 p.m. UT). May your skies be clear tonight!

Put Yourself in the Way of Beauty

Oh my, oh my. Rolando Ligustri captured this scene last night as Comet Q2 Lovejoy swished past the globular cluster M79 in Lepus. If you’ve seen the movie Wild or read the book, you’ll be familiar with the phrase “put yourself in the way of beauty”, a maxim for living life adopted by one of its characters. When I opened up my e-mail today and saw Rolando’s photo, I felt like the beauty truck ran right over me.

Another striking image of the comet's juxtaposition with the globular cluster M79. Lovejoy is presently 48 million miles from Earth; the cluster shines from the immense distance of 410,000 light years. Credit: Chris Schur
Another striking image of the comet’s juxtaposition with the globular cluster M79. Lovejoy is presently 48 million miles from Earth; the cluster lies at the immense distance of 41,000 light years. Credit: Chris Schur

More beautiful images arrived later including this one by Chris Schur of Arizona.

Even with the Moon at first quarter phase, the comet was plainly visible in binoculars last night shining at magnitude +5. I used 8x40s and had no problem seeing Lovejoy’s blobby glow. With a coma about 15-20 arc minutes in diameter or more than half the size of a the Full Moon, it really fills up the field of view when seen through a telescope at low to medium magnification.

A tighter view of the top image shows not only the star cluster but also shows 13th magnitude NGC 1886, an edge-on spiral galaxy. Credit: Rolando Ligustri
A tighter view of the top image shows not only the star cluster but also shows 13th magnitude NGC 1886, an edge-on spiral galaxy. Credit: Rolando Ligustri

If you love the aqua blue hues of the Caribbean, Lovejoy will remind you it’s time to book another tropical vacation. In both my 15-inch (37-cm) and 10-inch (25-cm) reflectors, the coma glowed a delicious pale blue-green in contrast to the pearly white cluster. I encourage you to look for the comet in the next few nights before the Moon is full. Starting on January 6-7, the Moon begins its move out of the evening sky, giving observers with dark skies a chance to view Lovejoy with the naked eye. I’m looking forward to seeing its long, faint tail twist among the stars of Eridanus as the comet rapidly moves northward over the next week.

Using Photoshop I made this drawing of the comet and cluster that captures its visual appearance through the telescope. Credit: Bob King
Using Photoshop I made this drawing of the comet and cluster that captures its visual appearance through the telescope last night December 28th. The nuclear region is very intense and bright and about 10 arc seconds across. Credit: Bob King

For a map on how to find the comet, check my recent article on Lovejoy’s many tails. Cheers to finding beauty the next clear night!

Comet Lovejoy was bright enough to nab in a 15-second time exposure with a 200mm telephoto lens last night. Details: f/2.8 at 13 seconds. Credit: Bob King
Comet Lovejoy was bright enough to nab in a 15-second time exposure with a 200mm telephoto lens last night. Details: f/2.8 at 13 seconds. Credit: Bob King

C/2014 Q2 Lovejoy – A Binocular Comet in Time for Christmas

Hmmm. Something with a long white beard is making an appearance in northern skies this week. Could it be Santa Claus? No, a bit early for the jolly guy yet, but comet watchers will soon find a special present under the tree this season.  Get ready to unwrap Comet Lovejoy Q2, now bright enough to spot in a pair of 10×50 binoculars.

Comet Lovejoy Q2 starts out low in the southern sky below Canis Major this week but quickly zooms northward. Visibility improves with each passing night. Source: Chris Marriott's SkyMap software
Comet Lovejoy Q2 starts out low in the southern sky in Puppis this week (6° max. altitude on Dec. 9) but quickly zooms north and west with each passing night. On the night of December 28-29, the comet will pass 1/3° from the bright globular cluster M79 in Lepus. This map shows the sky and comet’s position facing south from 42° north latitude around 1:30 a.m. CST. Source: Chris Marriott’s SkyMap software

Following a rocket-like trajectory into the northern sky, this visitor from deep space is no longer reserved for southern skywatchers alone. If you live in the central U.S., Lovejoy Q2 pokes its head from Puppis in the early morning hours this week. Glowing at magnitude +7.0-7.5, it’s a faint, fuzzy cotton ball in binoculars from a dark sky and visible in telescopes as small as 3-inches (7.5 cm). With the Moon past full and phasing out of the picture, comet viewing will continue to improve in the coming nights. What fun to watch Lovejoy gradually accelerate from its present turtle-like amble to agile cheetah as it leaps from Lepus to Taurus at the rate of 3° a day later this month. Why the hurry? The comet is approaching Earth and will pass nearest our planet on January 7th at a distance of 43.6 million miles (70.2 million km). Perihelion follows some three weeks later on January 30th.

Image triplet taken by Terry Lovejoy on which he discovered the comet. The comet moves slightly counterclockwise around the larger fuzzy spot. Credit: Terry Lovejoy
Terry Lovejoy discovered the comet in this triplet of images taken on August 17th. The comet moves slightly counterclockwise around the larger fuzzy spot during the sequence. Credit: Terry Lovejoy

The new object is Australian amateur Terry Lovejoy’s 5th comet discovery. He captured images of the faint, 15th magnitude wisp on August 17th with a Celestron C-8 fitted with a CCD camera at his roll-off roof observatory in Brisbane, Australia. Comet Lovejoy Q2 has a period of about 11,500 years with an orbit steeply inclined to the plane of the Solar System (80.3°), the reason for its sharp northern climb. As December gives way to January the comet crosses from below to above the plane of the planets.

Another awesome shot of Comet Lovejoy Q2 taken on November 26, 2014. Gases in the coma fluoresce green in the Sun's ultraviolet light. Credit: Damian Peach
Another awesome shot of Comet Lovejoy Q2 taken on November 26, 2014. Gases in the coma including carbon and cyanogen fluoresce green in the Sun’s ultraviolet light. The comet’s moderately condensed coma currently measures about 8 arc minutes across or 1/4 the size of the full Moon. Credit: Damian Peach

Comet Lovejoy is expected to brighten to perhaps 5th magnitude as it approaches Earth, making it faintly visible with the naked eye from a dark sky site. Now that’s what I call a great way to start the new year!

To help you find it, use the top map to get oriented; the detailed charts (below) show stars to magnitude +8.0. Click each to enlarge and then print out a copy for use at night. Bonus! Comet Lovejoy will pass only 10 arc minutes (1/3°) south of the 8th magnitude globular cluster M79 on December 28-29 – a great opportunity for astrophotographers and observers alike. Both comet and cluster will pose side by side in the same binocular and telescopic field of view. In early January I’ll post fresh maps to help you track the comet all through next month, too.

Detailed map showing the comet tomorrow morning through December 27th in the early morning hours (CST). Stars shown to magnitude +8.0. Source: Chris Marriott's SkyMap software
Detailed map showing the comet tomorrow December 9th through December 27th in the early morning hours (CST). Stars shown to magnitude +8.0. Source: Chris Marriott’s SkyMap software
Because Comet Lovejoy rapidly moves into the evening sky by mid-late December, its position on this detailed map is shown at 10 p.m. (CST) nightly. Credit:
Because Comet Lovejoy moves rapidly into the evening sky by mid-late December, its position on this detailed map is shown for 10 p.m. (CST) nightly. Credit: Chris Marriott’s SkyMap software

Better than Bieber, Rosetta’s Comet Sings Strange, Seductive Song


Tune in to the song of Comet Churyumov-Gerasimenko

Scientists can’t figure exactly why yet, but Comet 67P/Churyumov-Gerasimenko has been singing since at least August. Listen to the video – what do you think? I hear a patter that sounds like frogs, purring and ping-pong balls. The song is being sung at a frequency of 40-50 millihertz, much lower than the 20 hertz – 20 kilohertz range of human hearing. Rosetta’s magnetometer experiment first clearly picked up the sounds in August, when the spacecraft drew to within 62 miles (100 km) of the comet. To make them audible Rosetta scientists increased their pitch 10,000 times. 

The sounds are thought to be oscillations in the magnetic field around  the comet. They were picked up by the Rosetta Plasma Consortium,  a suite  of five instruments on the spacecraft devoted to observing interactions between the solar plasma and the comet’s tenuous coma as well as the physical properties of the nucleus. A far cry from the stuff you donate at the local plasma center, plasma in physics is an ionized gas. Ionized means the atoms in the gas have lost or gained an electron through heating or collisions to become positively or negatively charged ions. Common forms of plasma include the electric glow of neon signs, lightning and of course the Sun itself.

Having lost their neutrality, electric and magnetic fields can now affect the motion of particles in the plasma. Likewise, moving electrified particles affect the very magnetic field controlling them.

Scientists think that neutral gas particles from vaporizing ice shot into the coma become ionized under the action of ultraviolet light from the Sun. While the exact mechanism that creates the curious oscillations is still unknown, it might have something to do with the electrified atoms or ions interacting with the magnetic fields bundled with the Sun’s everyday outpouring of plasma called the solar wind. It’s long been known that a comet’s electrified or ionized gases present an obstacle to the solar wind, causing it to drape around the nucleus and shape the streamlined blue-tinted ion or gas tail.

“This is exciting because it is completely new to us. We did not expect this, and we are still working to understand the physics of what is happening,” said Karl-Heinz Glassmeier, head of Space Physics and Space Sensorics at the Technical University of Braunschweig, Germany.

While 67P C-G’s song probably won’t make the Top 40, we might listen to it just as we would any other piece of music to learn what message is being communicated.

Astrophotographers Capture Dramatic Photos of Comet Siding Spring Approaching Mars

Astrophotographer Damian Peach shares this spectacular image of comet C/2013 A1 Siding Spring approaching Mars taken just hours ago.  The faint comet shows a small, condensed coma and bent tail against the glaring orange glow of the brilliant planet. Most photos of comets passing by a planet or deep sky object are lucky line-of-sight pairings with the comet in the foreground and object light years away in the background. Not this one. Both Siding Spring and Mars lie at nearly the identical distance from Earth of 151 million miles (243 million km).  

Artist view of the comet passing closest to Mars this Sunday. At the time, the Mars orbiters from the U.S., Europe and India will be huddled on the opposite side of the planet to avoid possible impacts from comet dust. Credit: NASA
Artist view of the comet passing closest to Mars this afternoon October 19. At the time, the Mars orbiters from the U.S., Europe and India will be huddled on the opposite side of the planet to avoid possible impacts from comet dust. Credit: NASA

When closest to Mars this afternoon, Siding Spring is expected to shine at around magnitude -5 or about twice as bright as Venus. Mind you, that estimate considers the entire comet crunched down into a dot. But for those who remember, Comet Hale-Bopp remained at zero magnitude, 100 times fainter than Siding Spring, and made for one of the most impressive naked eye sights on spring evenings in 1997.

More recently, Comet McNaught climaxed at magnitude -5 in the daytime sky near the Sun in January 2007. It was plainly visible in binoculars and telescopes in a blue sky  if you knew exactly where to look and took care to avoid the Sun. Would-be Martians are far more fortunate, with Siding Spring appearing high overhead in a dark sky from some locations, including that of NASA’s Curiosity Rover.


Comet C/2013 Siding Spring as it rises and sets over the Curiosity Rover this weekend October 18-19. Credit: Solarsystemscope.com

Right on time for today’s encounter, the folks at Solarsystemscope.com have rolled out an interactive simulation of Comet Siding Spring’s appearance in the sky above Curiosity. Just click the play button on the control panel above to run it live. Seen from Mars, the comet bobs along Eridanus the River southwest of Orion, passing high in the southern sky overnight. What a sight!

Another photo, just in, taken of the comet and Mars today by Rolando Ligustri. Beautiful!
Another photo, just in, taken of the comet and Mars today by Rolando Ligustri. Beautiful!

The comet nucleus is only about 0.4 miles (700 meters) across, but the coma or atmosphere fluffs out to around 12,000 miles (19,300 km). Seen from the ground, Siding Spring would span about 8°of sky or 16 full Moons from head to tail. Moving at 1.5° per minute, we could watch crawl across the heavens in real time with the naked eye. Wish I zoom to Mars for a look, but the rovers and orbiters will be our eyes as they study and photograph the comet during its brief flyby. As soon as those pictures become available, we’ll publish them here. Can’t wait!


Come Siding Spring comes out the other side!

While we’re waiting, amateur astronomers have been busy shooting additional photos and creating videos from their images. Fritz Helmut Hemmerich made this video from 1200-meters at Tenerife in the Canary Islands showing Comet Siding Spring immediately after its Mars encounter. One thing we know for certain is that the comet is intact after its close brush.

Negative image showing Comet Siding Spring closely approaching Mars today. Credit: Peter Lake
Negative image showing Comet Siding Spring closely approaching Mars today. Credit: Peter Lake

And find our more amazing photos and information at Sen TV, and you can follow them on Twitter at @sen.

PanSTARRS K1, the Comet that Keeps Going and Going and Going

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.

Comet C/2012 K1 PanSTARRS' changing appearance over the past year. Credit upper left clockwise: Carl Hergenrother, Damian Peach, Chris Schur and Rolando Ligustri
Comet C/2012 K1 PanSTARRS’ changing appearance over the past year. Credit upper left clockwise: Carl Hergenrother, Damian Peach, Chris Schur and Rolando Ligustri

Many amateur astronomers first picked up the comet’s trail in the spring of 2013 when it had brightened to around magnitude 13.5. My observing notes from June 2, 2013, read:

“Very small, about 20 arc seconds in diameter. Pretty faint at ~13.5 and moderately condensed but not too difficult at 142x . Well placed in Hercules.” Let’s just say it was a faint, fuzzy blob.

K1 PanSTARRS slowly brightened in Serpens last fall until it was lost in evening twilight. Come January this year it returned to the morning sky a little closer to Earth and Sun and a magnitude brighter. As winter snow gave way to frogs and flowers, the comet rocketed across Corona Borealis, Bootes and Ursa Major. Its fat, well-condensed coma towed a pair of tails and grew bright enough to spot in binoculars at magnitude 8.5 in late May.

Skywatchers can find C/2012 K1 PanSTARRS in the morning just in Hydra-Puppis just before dawn. The map shows its location daily with stars to magnitude 8.5. The numbers next to some stars are standard Flamsteed atllas catalog numbers. Source: Chris Marriott's SkyMap
Skywatchers can find C/2012 K1 PanSTARRS in the morning sky in the Hydra and Puppis just before dawn when it’s highest in the southeastern sky. The map shows its location daily with stars to magnitude 8.5. The numbers next to some stars are standard Flamsteed atlas catalog numbers. Click for a larger version. Source: Chris Marriott’s SkyMap

By July, it hid away in the solar glare a second time only to come back swinging in September’s pre-dawn sky.  Now in the constellation Hydra and even closer to Earth, C/2012 K1 has further brightened to magnitude 7.5. Though low in the southeast at dawn, I was pleasantly surprised to see it several mornings ago. Through my 15-inch (37-cm) reflector at 64x I saw a fluffy, bright coma punctuated by a brighter, not-quite-stellar nucleus and a faint tail extending 1/4º to the northeast.

Mid-northern observers can watch the comet’s antics through mid-October. From then on, K1 will only be accessible from the far southern U.S. and points south as it makes the rounds of Pictor, Dorado and Horologium. After all this time you might think the comet is ready to depart Earth’s vicinity. Not even. C/2012 K1 will finally make its closest approach to our planet on Halloween (88.6 million miles – 143 million km) when it could easily shine at magnitude 6.5, making it very nearly a naked-eye comet.

PanSTARRS K1’s not giving up anytime soon. Southern skywatchers will keep it in view through the spring of 2015 before it returns to the deep chill from whence it came. After delighting skywatchers for nearly two years, it’ll be hard to let this one go.

New Mosaic Reveals Jets Blasting from Rosetta’s Comet

Hidden among the four new images of Comet 67P/Churyumov-Gerasimenko released by ESA this week are a pair of dusty jets shooting from the nucleus of Comet Churyumov-Gerasimenko. The photos were taken September 2, 2014 and posted as a mosaic of four separate images. I re-assembled the four, albeit imperfectly, and added some additional contrast to better show the dual geyser of ice crystals mixed with dust venting from the nucleus. 

Four image montage of comet 67P/C-G, using images taken on 2 September. Credits: ESA/Rosetta/NAVCAM
Original four image montage of comet 67P/C-G, using images taken on September 2. The dark spot at center is imaging artifact. Credits: ESA/Rosetta/NAVCAM

An earlier Rosetta photo taken of Comet 67P/ Churyumov-Gerasimenko from a great distance and deliberately overexposed showed jets of dust-laden vapor shooting from the comet, but this is the first image I’m aware of that shows both the comet’s surface and its much fainter exhalations.

Jets or sprays of vaporizing ice are what gives a comet its lively appearance. Dust released with water vapor is ultimately pushed back by the pressure of sunlight to grow 67P/C-G’s dust tail. Ultraviolet light from the sun causes volatiles within the vapor to fluoresce a pale blue, creating a second ion or gas tail. The coma or comet atmosphere is a mix of both.

Rosetta took a long-exposure image with its wide-angle camera on August 2, 2014, to observe jets of dust escaping from the comet. The photo was taken from a distance of 550 kilometers. ESA / Rosetta / MPS for OSIRIS Team MPS / UPD / LAM / IAA / SSO / INTA / UPM / DASP / IDA
On August 2, 2014 at distance of 342 miles (550 km), Rosetta took this wide-angle view of the comet and jets of dust and vapor shooting into space.
ESA / Rosetta / MPS for OSIRIS Team MPS / UPD / LAM / IAA / SSO / INTA / UPM / DASP / IDA

We can expect the jets to grow stronger and hopefully more numerous as 67P/C-G approaches perihelion in August 2015. Because the spacecraft is maneuvering into orbit between the comet and sun, we don’t get the best view of jetting activity. The comet nucleus, illuminated by sunlight, drowns out the fainter jets. Rosetta will make an excursion to the nightside on September 24. Assuming the jets remain active, we might see them backlit by the sun as bright beams extending from the darkened nucleus into space.