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The image shows Comet McNaught. Credit: fir0002.

A comet is a small solar system body that has a solid icy nucleus. When near the Sun a comet can also have an extremely tenuous atmosphere called the coma which can grow into a large and bright tail.


An image of Christensen who discovered C/2006 W3 (Christensen). Credit: .


Still other comets have dangerously close orbits to the sun and dozens have been found in recent years by a solar observing spacecraft plummeting into our nearest star.

Comet Bennett 1970 II[edit]

The velocities of the cyan molecule as produced in the head of comet Bennett 1970 II have been measured.[1]

Comet Borrelly[edit]

"A typical comet nucleus has an albedo of 0.04.[2]"[3]

Comet Halley[edit]

“During the Halley Monitoring Program at La Silla from Feb.17 to Apr.17,1986 ... In the light of the neutral CN-radical a continuous formation and expansion of [cyan] gas-shells could be observed.”[4] “The gas-expansion velocity decreases with increasing heliocentric distance from 1 km/s in early March to 0.8 km/s in April.”[4]


The image shows Comet 17P/Holmes. Credit: .
Comet Holmes (17P/Holmes) in 2007 shows a blue ion tail on the right. Credit: Ivan Eder.

On Oct 23, 2007, J. A. Henríquez Santana in the Canary Islands and Ramón Naves in Barcelona noticed an impressive spectacle, a bright and large comet gleemed through the bright full moon in the constellation Perseus. This was not a new comet, yet it was a supposedly boring one. The comet 17P Holmes was supposed to be a meagre 17th magnitude, far too dim for most telescopes to even detect in the bright moonlight.

The comet had suddenly brightened a half a million times and was easily seen by the unaided eye. Such is the importance of keeping an eye out for changes in a known comets. Within days, the most powerful telescopes on the Earth (and the one above it, the Hubble Space Telescope) would be viewing it.

So I make it a daily ritual to check out and record as many details as I can about each viewable comet and like to be aware for new things while I'm at my telescope.

An extremely good web page for comets is Greg Crinklaw's Skyhound and by coincidence Holmes is coming out of the glare fo the sun. We should keep tabs on it!

Comet Kohoutek 1973 XII[edit]

The neutral cyan coma of comet Kohoutek 1973 XII is measured.[5]

Comet Lovejoy[edit]

Comet Lovejoy has a blue ion tail leading away off to the left. Credit: NASA/Dan Burbank.

Comet Lulin[edit]

Recent changes in Comet Lulin's greenish coma and tails are shown in these two panels taken on January 31st (top) and February 4th (bottom) 2009. In both views the comet has an apparent antitail to the left of the coma of dust. Credit: Joseph Brimacombe, Cairns, Australia.

Shown at the right "Lulin's green color comes from the gases that make up its Jupiter-sized atmosphere. Jets spewing from the comet's nucleus contain cyanogen (CN: a poisonous gas found in many comets) and diatomic carbon (C2). Both substances glow green when illuminated by sunlight".[6]

Comet McNaught[edit]

McNaught Comet is captured in visual color with a Canon 350D...EF50...F2...25 sec. Credit: Davewhite7.

Comet Swan[edit]

This is a real color composite image of Comet Swan. Credit: Ginger Mayfield.

"Comet Swan recently made a swing through the inner solar and emerged in the evening sky. Astronomy enthusiast Ginger Mayfield recorded the blue-green color of the comet's nucleus and a tenuous tail in this composite created from multiple images taken on October 26 from Divide, Colorado."[7]

Comet West 1976 VI[edit]

Visual photograph of Comet West in early March 1976 shows red gases coming off the comet's head and multicolor dust tail. Credit: Peter Stättmayer (Munich Public Observatory) and ESO.

The physical parameters of the neutral cyan coma of comet West (1975n) have been measured.[8]

Kuiper Belt[edit]

Occasionally inteferences with the large gas giants of our solar system (Jupiter and Saturn) will further alter their orbit. These comets commonly roam in an area called the Kuiper belt, that surrounds the last planet Neptune. The orbits of these comets vary highly from the diminuitive comet Encke (3 years) to the famed comet Halley seen only once maybe twice a lifetime (76 years).

Oort Cloud[edit]

Most of the comets lay at the distant reaches of our system in a hypothesized Oort cloud. At the very edge of the solar these comets orbit in very large loops around the distant reaches of our solar system. The passing of nearby stars, or other objects can alter their orbit, sending them speeding towards the inner reaches of our solar system. these comets typically retain very large orbits such that they will not return (once seen in the inner solar system) for many thousands of years.


"A comet seeker is a type of small telescope adapted especially to searching for comets: commonly of short focal length and large aperture, in order to secure the greatest brilliancy of light."[9]


Irregardless of where comets come from or go. Comets are a regular visitor the inner solar system. Because comets cannot be detected at the furthest reaches of our solar system, there is always the chance for a dramatic visit by a truly well-traveled visitor. Amatuer astronomers have been enthusiastic searchers for these cosmic visitor since the beginning of time and according to astronomical convention, whomever first finds the comets, has their name immortalized in the heavens.

Currently visible in a small scope (6" or less)[edit]

Comets visible during October 2008 (place any observations below and include time, date, location, and any observable features)

17P/Holmes: A morning comet near Cancer visible in binoculars

Very good to see as it has not been widely seen yet, its brightness and location might be useful to report

C/2008 A1 (McNaught): An evening comet in Ophiuchus visible in binoculars

C/2006 W3 (Christensen): A evening comet in Cassiopeia visible in small telescopes

* Tough comet in a smalltown sky (5.0magn); I see a spherical 3' glow with little condensation and no nucleus.--Jolie (254mm reflector at 79X at Fri Oct 24,08 2:45UTC)
* Hazy conditions, and much light pollution. --mikeu (16" f/10 SCT with CCD on 2008-11-22T02:53:23 UTC)

C/2006 OF2 (Broughton): A morning comet in Camelopardalis visible in small telescopes

* Dim but definite in a smalltown sky (5.0magn); spherical with some condensation and a very faint nucleus. --Jolie (254mm reflector at 79X at Fri Oct 24,08 5:55UTC)

19P/Schwassmann-Wachmann: A morning comet in Cancer visible in small telescopes

good to keep a watch on as it had a tendency for outbursts

C/2008 J1 (Boattini): A far-northern evening comet in Camelopardalis visible in a 6-inch telescope

205P/Giacobini: An evening comet in Aquarius visible in a 6-inch telescope

Wow, that is an impressively large list to be able to seen in a 6" or smaller telescope!--Jolie 16:38, 23 October 2008 (UTC)

See also[edit]


  1. I. N. Matveev (1982). "Determination of velocities of cyan molecule production in the head of comet Bennett 1970 II". Kometnyj Tsirkulyar (286). 
  2. Robert Roy Britt (2001-11-29). "Comet Borrelly Puzzle: Darkest Object in the Solar System". Retrieved 2012-09-01. 
  3. "Albedo, In: Wikipedia". San Francisco, California: Wikimedia Foundation, Inc. April 24, 2013. Retrieved 2013-05-01. 
  4. 4.0 4.1 Wolfhard Schlosser, Rita Schulz, Paul Koczet (1986). The cyan shells of Comet P/Halley, In: Proceedings of the 20th ESLAB Symposium on the Exploration of Halley's Comet. 3. European Space Agency. pp. 495-8. Bibcode: 1986ESASP.250c.495S. 
  5. RS Amirkhanov, KI Churyumov, Gorodetsij (1978). "Physical parameters of the neutral cyan coma of comet Kohoutek, 1973 XII.". Kometnyj Tsirkulyar (220). 
  6. James A. Phillips (2009). "Green Comet Approaches Earth". National Aeronautics and Space Administration Science News. Retrieved 2012-05-05. 
  7. Space Archive (November 4, 2006). "Comet Swan". Retrieved 2014-02-22. 
  8. V. A. Oshchepkov, N. M. Shiper (1978). "Physical parameters of the neutral cyan coma of comet West (1975n)". Kometnyj Tsirkulyar (234). 
  9. "Comet seeker, In: Wikipedia". San Francisco, California: Wikimedia Foundation, Inc. March 6, 2013. Retrieved 2014-01-03. 

External links[edit]

Nuvola apps kmoon.png Subject classification: this is an astronomy resource.