COMETS ARRIVING

2007

Space Weather News for March 20, 2007
http://spaceweather.com

GREEN COMET: There's a new comet in the southern hemisphere: Comet Lovejoy (C/2007 E2). Terry Lovejoy of Australia discovered it on March 15th using, remarkably, not a telescope but only an off-the-shelf digital camera. The green comet is too dim to see with the naked eye, but it is a nice target for backyard telescopes. After five days of monitoring, the comet's orbit is now known with some accuracy and it is possible to make predictions about Comet Lovejoy's future movements and brightness. Visit http://spaceweather.com for details.

By Joe Rao
SPACE.com Skywatching Columnist
posted: 30 March 2007
06:00 am ET

A new comet has recently been discovered, and like the brilliant Comet McNaught from earlier this year, this latest discovery belongs to an Australian: Comet Lovejoy (C/2007 E2).

On March 15th, Terry Lovejoy of Thornlands, Queensland, Australia, discovered a 9th-magnitude comet in the southern constellation Indus the Indian. In reporting the find to the Central Bureau for Astronomical Telegrams (CBAT), in Cambridge, Massachusetts, Lovejoy described the comet as having a coma that appeared distinctly green in color, with a slight extension to the southwest.

Remarkably, Lovejoy made the discovery not with a telescope but using an off-the-shelf digital camera! In fact, it appears to be the very first case of the discovery of a comet discovered in this manner.

Lovejoy was using a Canon 350D with a zoom lens set to 200-mm focal length at f/2.8. Lovejoy spotted the object near the frame edge in 16 exposures of 90 seconds each. The images were obtained during a comet-hunting survey that Lovejoy has been conducting for more than two years.

The first independent confirmation was obtained by John Drummond (Possum Observatory, Gisborne, New Zealand) on March 16. He used a 41-cm reflector and visually estimated the magnitude as 9.5—about 15 times dimmer than the faintest sky objects that can be seen without optical aid. Drummond estimated the coma diameter as 2.6 arc minutes (roughly equal to about 1/12 that of the apparent width of the Moon).

The green comet is too dim to see with the naked eye, but it’s a nice target for backyard telescopes. The first official orbit was calculated by Brian G. Marsden of the CBAT on March 19. He took 36 precise positions spanning a three day interval and determined the comet's perihelion date (when it will sweep closest to the Sun—a distance of 101.3 million mi/163 million km.) as March 27. The comet's distinctive greenish hue seems to suggest that it is rich in cyanogens and diatomic carbon.

Unlike Comet McNaught, which took a southerly route after passing the Sun, Comet Lovejoy will be progressing north during April and will soon become favorably placed for observation for observers in the Northern Hemisphere. Also unlike Comet McNaught, Comet Lovejoy will (unfortunately) not become a naked-eye object; it probably will get no brighter than magnitude +7.5. That's still about two and a half times fainter than the faintest naked-eye star. But it still should continue to be an interesting object to follow with binoculars and small telescopes as it moves north during April.

For most northern observers, it will not be until the second week of April that Comet Lovejoy will emerge from out of the dawn twilight and be positioned low in the southeast sky.

It will be located between the constellations of Capricornus the Sea Goat and Sagittarius the Archer [sky map]. During April 20-25, the comet will appear to cross the Milky Way while passing through the southern half of Aquila the Eagle. This is also about the time when it will be passing closest to Earth (41 million mi/66 million km, Apr. 24-26) and should appear at its brightest. Toward month's end, it will glide between Lyra the Lyre and Hercules, and appearing to pass almost directly overhead at around 3 a.m. local daylight time.

On Comets ml—an Internet forum dedicated to the discussion of comets, Terry Lovejoy posted his thoughts after he made his discovery: "After a very intense search effort in 2006 without success, I had wound back my efforts in 2007 (partly because of fatigue!). March 15 was only the second time this year I had done any searches in the morning sky. All told I estimate I have examined about 1000 image fields since late 2004, which would equate to about 1000 hours. 2007 has been a good year with two lifetime astronomy goals finally achieved. The first goal was to see a daylight comet (McNaught) and the second to discover a comet."

"Mission accomplished!"

September 27, 2007

SOHO Mission Discovers Rare Comet

Periodic comet P/2007 R5 (SOHO), seen with SOHO's Large Angle and Spectrometric Coronagraph camera. A yellow box has been added to the picture to highlight the tiny comet, which appears as a white dot in the center. Credit: ESA/NASA

The Solar and Heliospheric Observatory (SOHO) has discovered a rare periodic comet. SOHO has already discovered more than 1,350 comets during its mission, but this is the first time one of its discoveries officially has been designated periodic.

Many of the comets SOHO has discovered are believed to be periodic, meaning they follow their orbits around the sun more than twice and have orbital periods of less than 200 years. Thousands of comets have been seen by astronomers, but only around 190 are classified as periodic. The most famous periodic comet is Halley’s Comet, which returns every 76 years. It most recently passed close to the sun in 1986.

SOHO’s new find has a much smaller orbit than Halley's Comet. It takes the comet approximately four years to travel once around the sun. It was first seen in September 1999 and then again in September 2003. In 2005, German PhD student Sebastian Hoenig realized that the two comets were so similar in orbit that they might actually be the same object. To test his theory, he calculated a combined orbit for the comet and consequently predicted that it would return on Sept. 11, 2007. Hoenig's prediction proved to be extremely accurate -- the comet reappeared in SOHO's Large Angle and Spectrometric Coronagraph camera right on schedule and has now been given the official designation of P/2007 R5 (SOHO). Credit for the original discovery and recovery of the object goes to Terry Lovejoy (Australia, 1999), Kazimieras Cernis (Lithuania, 2003) and Bo Zhou (China, 2007).

A puzzling aspect to P/2007 R5 (SOHO) is that it does not look exactly like a comet. It has no visible tail or coma of dust and gas, as is traditionally associated with the phenomena. Initially, this led some scientists to wonder if the object was actually an asteroid, a chunk of space-rock, rather than a chunk of space-ice. However, P/2007 R5 (SOHO) did exhibit some characteristics consistent with a comet. As scientists watched the object pass close to the sun, drawing to within 4.9 million miles, or around 5% of the distance between the Earth and the sun, they saw it brighten by a factor of around a million, which is common behavior for a comet.

“It is quite possibly an extinct comet nucleus of some kind,” says Karl Battams of the Naval Research Laboratory, Washington, who runs SOHO's comet discovery program. Extinct comets have expelled most of their volatile ices and retain little to form a tail or coma. They are theorized to be common objects among the celestial bodies orbiting close to the sun.

This comet faded as quickly as it brightened, and soon became too faint for SOHO's instruments to see. Estimates show that P/2007 R5 (SOHO) is probably only 100 to 200 yards in diameter. Given how small and faint this object is, and how close it still is to the sun, it is an extremely difficult target for observers on Earth to pick out in the sky.

Now we know for certain that P/2007 R5 (SOHO) is there, astronomers will be watching closely for it during its next return in September 2011.

COMET 17 P - COMET HOLMES

Passing Comet in Suprise Flare-Up, Visible To Naked Eye

By John Borland October 25, 2007 | 8:09:47 AMCategories: Space Astronomy blogs and boards are buzzing today with news that a relatively obscure comet making a pass near Earth has brightened unexpectedly, to the point of looking like a supernova, say some.

The comet, called 17/P Holmes, has apparently reached the point where it is visible to the naked eye, even near well-lit areas with a near-full moon, amateur astronomers write. Holmes is in outburst mode – a point where a comet releases ice or other particles, increasing its size and reflectivity – but the magnitude of the increase has surprised everyone.

For now, the comet is visible in the Perseus constellation, in the Northern hemisphere. Charts for the astronomically minded can be found here, while the history of the comet, first discovered in 1892, can be found here.

Astronomers write that the comet had been faintly visible since July, and had begun to fade. But on Wednesday, observers around the world began reporting a dramatic flare-up, to the point where even naked eye viewing was possible.

Unfortunately, it's cloudy where I'm sitting, with no sign of clearing in the near future. Here's hoping Holmes keeps bursting.

Discussion at IrishAstronomy.org

Surprise Outburst of Comet Holmes Observed [Bart Busschots]

(Image: A cropped photo of the 17P Holmes outburst, with the coma, or surrounding gas cloud visible. Credit: MrMoorey)

Comet Holmes Photo: Obscure Comet 17P/Holmes Suddenly Brightens
by Jack Ryan
Comet Holmes Brightens - There's a brand-new bright light in the sky that will soon appeal to the stargazers among us -- specifically an abrupt, unexpected increase in the magnitude of Comet 17P/Holmes, reports USA Today.

You've probably never heard of Comet 17P/Holmes. That's because it normally shows at a magnitude of around 17, that's about 25,000 times fainter than the faintest star that can normally be seen without any optical aid. In order to view an object this faint, one would need a moderately large telescope.

But overnight, it suddenly brightened to a 3 magnitude, which means it is now very visible. See a photo here.

Comet Holmes was discovered in November 1892 by Edwin Holmes in London England and is not as dramatic as some. Holmes lacks the characteristic tail that makes many of these frozen travelers so beautiful. It is currently located among the stars of the constellation Perseus, which can be found about halfway up in the northeast part of the sky as darkness falls.

Exactly why Comet Holmes has undergone such an incredible transition is not understood. What is amazing is that it made its closest approach to the sun last May, but came no closer than 191 million miles (307 million kilometers) to the sun, reports Space.com. The comet is now moving away from the sun and currently is 151 million miles (243 million kilometers).

Only about 175 actual stars are brighter. As to what this object will do in the coming days and weeks is not known.

STRANGE COMET: Astronomers around the world agree, Comet 17P/Holmes is one of the strangest things ever to explode in the night sky. It's a comet, yet it looks like a planet with a golden core and a green atmosphere:

Chris Shur of Payson, Arizona, took this picture last night using his 12.5-inch telescope and a Canon XTi digital camera. "The comet was yellow and green, very bright in the viewfinder," he says.

Yesterday, Comet Holmes shocked sky watchers with a spectacular eruption, brightening almost a million-fold from 17th to 2.5th magnitude in a matter of hours. The comet is now visible to the naked eye--even from light polluted cities--high in the northern sky after sunset: finder chart.

MEGAOUTBURST STRANGE COMET: Astronomers around the world agree, Comet 17P/Holmes is one of the strangest things ever to explode in the night sky. It's a comet, yet it looks like a planet with a golden core and a green atmosphere...

HOT NEWS: Comet 17P/Holmes shocked astronomers today with a spectacular eruption. The 17th magnitude comet has brightened by a factor of five hundred thousand or more during the past 24 hours becoming a naked-eye object in the evening sky. Look for a golden 2.5th magnitude fuzzball in the constellation Perseus after sunset. "This is unbelievable!" says Iranian astronomer Babak Tafreshi. "I was amazed to find Comet Holmes so easily with the naked-eye in the light-polluted skies of metropolitan Tehran."

Pictures of 17P/Holmes (2007) More C/2006 P1(McNaught) 73P/Schwassmann-Wachmann 3 Deep Impact Tempel 1 Comments 2

Is Comet 17P/Holmes losing its tail?" asks Italian astronomer Paolo Berardi. "Last night I recorded an image showing a big disconnection event that was not present on Nov 8th."

Jack Newton of the Arizona Sky Village saw it, too: image. "The comet has a huge eruption moving along its tail. Holmes is more bizarre with each passing day."

This event does not necessarily signal a new outburst of Comet Holmes. Comet tails can be disconnected by gusts of solar wind which trigger magnetic storms around the comet akin to geomagnetic storms which fuel auroras on Earth. Such a storm and disconnection was observed earlier this year in the tail of Comet Encke: full story.

Got a telescope? Monitoring is encouraged: sky map, ephemeris.

3D BONUS: Grab your 3D glasses. Graphic artist Patrick Vantuyne has combined two photos of Comet Holmes, one taken by Jack Newton in Arizona and one by Ivan Eder in Hungary, to create an eye-popping stereo portrait: stereo image. "The stereo effect has nothing to do with the different locations of the photographers," he notes. "It is a result of the movement of the comet among between the two pictures."

Comet 17P/Holmes Photo Gallery
[Interactive World Map of Comet Photos]
[sky map] [ephemeris] [3D orbit] [Night Sky Cameras]

The Lunar Month of Nov 9, 2007 - Dec 9,2007

Ocurring on the New Moon of Nov 9, 2007
Comet's Tail breaks away.

"COMET TAIL: Exploding Comet 17P/Holmes continues to amaze onlookers. On Nov. 8th and 9th part of the comet's blue tail broke away in view of many backyard telescopes. Visit http://spaceweather.com (Nov 10 to see photos of the "disconnection event" and speculation about what might have caused it." (Quote from SpaceWeather.com)

The Full Moon of the Nov 9 Lunar Cycle conjoins Comet Holmes and Mirphak in Perseus An excerpt from the Nov 9, 2007 Lunar Planner: "Comet Holmes' dramatic eruption in Perseus occurred in the last lunar cycle (Oct 07). The Full Moon of Nov 24, 2007 significantly conjoins Holmes while retrograde Holmes and Mirphak conjoin in both ecliptical longitude and latitude. What a significator! Comet Holmes illumines and accentuates this Mirphak Full Moon theme; and perhaps our need to rise-to the occasion as the hero Perseus does in his initiatory journey to claim the success and achievement that Mirphak embodies. The realizations this Full Moon offers, whatever they may be for each of us, may be of extreme significance."

More on Comet Holmes
http://lunarplanner.com/Snippets/snippet.07.11.01-CometHolmes.html

A few topics presented in the Nov 9, 2007 Lunar Planner:

* Relationships in the Balance
* Mars Retrograde begins
* Action - From the Heart of the Swan
* The Opening - The Jupiter Pluto Synodic Cycle & the next 13 years
* The Full Moon: Comet Holmes, Perseus, & the Pleiades
* A Moon Wobble
* Varuna establishes a new order
* Mercury and Juno in Scorpio
* Setting a new course
* Places of the Heart & the Venus bi-polar Vortex

The Lunar Planner
http://www.lunarplanner.com

Passing Comet in Suprise Flare-Up, Visible To Naked Eye

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