Tag Archives: Comets

Cloud, Clusters and Comet Siding Spring 

Image Credit & Copyright: Rolando Ligustri (CARA Project, CAST)

 On October 19th, a good place to watch Comet Siding Spring will be from Mars. Then, this inbound visitor (C/2013 A1) to the inner solar system, discovered in January 2013 by Robert McNaught at Australia’s Siding Spring Observatory, will pass within 132,000 kilometers of the Red Planet. That’s a near miss, equivalent to just over 1/3 the Earth-Moon distance. Great views of the comet for denizens of planet Earth’s southern hemisphere are possible now, though. This telescopic snapshot from August 29 captured the comet’s whitish coma and arcing dust tail sweeping through southern skies. The fabulous field of view includes, the Small Magellanic Cloud and globular star clusters 47 Tucanae (right) and NGC 362 (upper left). Worried about all those spacecraft in Martian orbit? Streaking dust particles from the comet could pose a danger and controllers plan to position Mars orbiters on the opposite side of the planet during the comet’s close flyby.

APOD NASA 04-Sep-14

Rosetta’s Rendezvous 


 On August 3rd, the Rosetta spacecraft’s narrow angle camera captured this stunning image of the nucleus of Comet 67P/Churyumov-Gerasimenko. After 10 years and 6.5 billion kilometers of travel along gravity assist trajectories looping through interplanetary space, Rosetta had approached to within 285 kilometers of its target. The curious double-lobed shape of the nucleus is revealed in amazing detail at an image resolution of 5.3 meters per pixel. About 4 kilometers across, the comet nucleus is presently just over 400 million kilometers from Earth, between the orbits of Jupiter and Mars. Now the first spacecraft to achieve a delicate orbit around a comet, Rosetta will swing to within 50 kilometers and closer in the coming weeks, identifiying candidate sites for landing its probe Philae later this year.

APOD NASA 07-Aug-14

Spacecraft Rosetta Shows Comet has Two Components 


 Why does this comet’s nucleus have two components? The surprising discovery that Comet 67P/Churyumov–Gerasimenko has a double nucleus came late last week as ESA’s robotic interplanetary spacecraft Rosetta continued its approach toward the ancient comet’s core. Speculative ideas on how the double core was created include, currently, that Comet Churyumov–Gerasimenko is actually the result of the merger of two comets, that the comet is a loose pile of rubble pulled apart by tidal forces, that ice evaporation on the comet has been asymmetric, or that the comet has undergone some sort of explosive event. Pictured above, the comet’s unusual 5-km sized comet nucleus is seen rotating over the course of a few hours, with each frame taken 20-minutes apart. Better images — and hopefully more refined theories — are expected as Rosetta is on track to enter orbit around Comet Churyumov–Gerasimenko’s nucleus early next month, and by the end of the year, if possible, land a probe on it.

APOD NASA 21-Jul-2014

Comet PanSTARRS with Galaxy 

Image Credit & Copyright: Alessandro Falesiedi

Sweeping slowly through northern skies, the comet PanSTARRS C/2012 K1 posed for this telescopic portrait on June 2nd in the constellation Ursa Major. Now in the inner solar system, the icy body from the Oort cloud sports two tails, a lighter broad dust tail and crooked ion tail extending below and right. The comet’s condensed greenish coma makes a nice contrast with the spiky yellowish background star above. NGC 3319 appears at the upper left of the frame that spans almost twice the apparent diameter of the full Moon. The spiral galaxy is about 47 million light-years away, far beyond the stars in our own Milky Way. In comparison, the comet was a mere 14 light-minutes from our fair planet. This comet PanSTARRS will slowly grow brighter in the coming months remaining a good target for telescopic comet watchers and reaching perihelion, its closest approach to the Sun, while just beyond Earth’s orbit in late August.

NASA APOD 06-Jun-14

Comet Lovejoy Over a Windmill


Image Credit & Copyright: Jens Hackmann
Lovejoy continues to be an impressive camera comet. Pictured above, Comet C/2013 R1 (Lovejoy) was imaged above the windmill in Saint-Michel-l’Observatoire in southern France with a six-second exposure. In the foreground is a field of lavender. Comet Lovejoy should remain available for photo opportunities for northern observers during much of December and during much of the night, although it will be fading as the month progresses and highest in the sky before sunrise. In person, the comet will be best viewed with binoculars. A giant dirty snowball, Comet Lovejoy last visited the inner Solar System about 7,000 years ago, around the time that humans developed the wheel.
NASA APOD 9 December, 2013

Comet Lovejoy through Mörby Castle Ruins


Image Credit & Copyright: P-M Hedén (Clear Skies, TWAN)

This new comet is quite photogenic. Comet Lovejoy, discovered only three months ago, was imaged through ruins of ancient Mörby Castle in Sweden last week sporting a green-glowing coma and tails trailing several degrees. The past few weeks have been an unusually active time for comet watchers as four comets were visible simultaneously with binoculars: ISON, Lovejoy, Encke, and LINEAR. C/2013 R1 (Lovejoy) comet is currently visible to the unaided eye from a dark location. As Monday’s new Moon will provide little glare, the next few days provide a good time to see Comet Lovejoy as it reaches its peak brightness. In two and a half weeks, Comet Lovejoy will reach its closest approach to the Sun at a distance just inside the orbital distance of the Earth.

Surprising Comet ISON

Image Credit: NASA, ESA, SOHO – Video Editing: Babak Tafreshi (TWAN)

After failing to appear for Sun staring spacecraft at perihelion, its harrowing closest approach to the Sun, sungrazing Comet ISON was presumed lost. But ISON surprised observers yesterday as material still traveling along the comet’s trajectory became visible and even developed an extensive fan-shaped dust tail. Edited and processed to HD format, this video (vimeo, youtube) is composed of frames from the SOHO spacecraft’s coronographs. It follows the comet in view of the wide (blue tint) and narrow (red tint) field cameras in the hours both before and after perihelion passage. In both fields, overwhelming sunlight is blocked by a central occulting disk. A white circle indicates the Sun’s positon and scale. With questions to be answered and the tantalizing possibility that a small cometary nucleus has survived in whole or part, surprising comet ISON will be rising before dawn in planet Earth’s skies in the coming days.

Comet ISON Before and After


Image Credit: NASA, SOHO

Sungrazing Comet ISON reached perihelion, its closest approach to the Sun, yesterday, November 28, at 18:45 UT. The comet passed just over 1 million kilometers above the solar surface, a distance less than the diameter of the Sun. These two panels follow ISON before (right) and after its close approach, imaged by the LASCO instrument onboard the Sun staring SOHO spacecraft. Overwhelming sunlight is blocked by LASCO’s central occulting disk with a white circle indicating the Sun’s positon and scale. The bright comet is seen along its path at the bottom of the before panel, but something much fainter exits near the top of the after panel, potentially a dust tail reforming from the debris left from ISON’s perihelion passage.

Comet ISON Rising

Video Credit & Copyright: Copyright: Juan Carlos Casado (TWAN, Earth and Stars)

Explanation: Will Comet ISON survive tomorrow’s close encounter with the Sun? Approaching to within a solar diameter of the Sun’s surface, the fate of one of the most unusual comets of modern times will finally be determined. The comet could shed a great amount of ice and dust into a developing tail — or break apart completely. Unfortunately, the closer Comet ISON gets to the Sun, the harder it has been for conventional telescopes to see the brightening comet in the glare of the morning Sun. Pictured in the above short time lapse video, Comet ISON was captured rising over the Canary Islands just above the morning Sun a few days ago. If the comet’s nucleus survives, the coma and the tails it sheds might well be visible rising ahead of the Sun in the next few days or weeks. Alternatively, satellites watching the Sun might document one of the larger comet disintegrations yet recorded. Stay tuned!