Category: Planetary

Comet 8P/Tuttle
By Martin Mc Kenna

8P/Tuttle Sketch on Dec 10/11th 2007 using a 8.5″ F/7 reflector with 32mm 1.25″ eyepiece. Tuttle was very high in the circumpolar sky within Cepheus approximately 1.5 degrees from Gamma Cephei – the naked eye star which marks the ‘roof’ of this house-shaped constellation. This sketch shows the position of Tuttle with respect to a triangle of bright field stars at 18.20, 20.13 and 21.55 UT. The comets rapid NE motion is very obvious. This is slow compared to how fast it will be moving when closest to the Earth during late December when it will be a faint naked eye object. The comet is a short period object with prograde motion meaning it moves around the Sun in its orbit in the same direction as the planets and main belt asteroids. The icy nucleus of this comet is several kilometers in diameter. If it hit the Earth it would most likely cause a near extinction event!.
Martin Mc Kenna

Comet 17P/Holmes
By Michael Rosolina

This is a recent view of the incredible, expanding, and ever-changing comet C17P/Holmes. Holmes is best viewed at low power so the observer can take in the entire coma, now greater in diameter than the Sun.

The outburst which produced this expansion may have a second act–the 1892 apparition had two outbursts about 75 days apart–so Holmes continues to be a worthwhile target for the amateur observer. It is best seen in a moonless sky, although the view holds up amazingly well even when Luna is present.

The sketch was done at the eyepiece with an HB graphite pencil, a blending stump, and a kneadable eraser on Strathmore 400 series 60 pound paper and inverted digitally after scanning.

Michael Rosolina
Friars Hill, WV USA

C/2002 C1 (Ikeya-Zhang)
By Martin Mc Kenna

C/2002 C1 Ikeya – Zhang on March 20th 2002 at 20.48 LT as seen through the 10X50mm binoculars. The 6 day old waxing crescent moon was high in the SW which drowned out the fainter secrets of the comet however I could still see a tail 7 degrees long which had a ‘forked’ appearance due to the possible detection of the fainter straight blue ion tail at a slight angle from the main dust tail.

The dust and ion tails were superimposed on one another at the time. With binoculars or the naked eye the comet was a pearly white colour however with the light grasp of a telescope one could see the tell tale blue signature of the more subtle and dynamic ion/gas/plasma tail. On March 3rd astrophotographers imaged a rare disconnection event within the ion tail caused by changes in the solar wind. Comet tails are the ‘wind socks’ of the solar system and hence observations and CCD images are of great importance to professional astronomers within this field.

Comet 8P/Tuttle
By Martin McKenna

Comet 8P/Tuttle will be making a noteworthy apparition over the next couple months, passing .25 AU from Earth on January 2nd. Although it could become visible to the naked eye for observers with dark skies, it is still rather faint. Martin McKenna made an early visual observation and sketch of the comet on the evening of November 14/15. Note that since the comet is sketched at an appropriately faint level, any incidental glare on your monitor may make it difficult to see.

Notes from Martin’s observation:
Last night (Nov 14/15th 2007) I made my first visual observation of 8P/Tuttle at 03.58 UT in an incredible sky between banks of thick fog. Tuttle was located in the high northern circumpolar sky below Polaris and not far to the SW of 4th magnitude Delta Ursae Minoris. Using the 8.5″ F/7 reflector with 32mm 1.25″ eyepiece I conducted a systematic search through this area without success as on previous nights. However I managed to catch the comet which surprised me after 45 minutes of fruitless searching. The comet was extremely faint and looked like a circular patch of green haze in a field of faint stars. Tuttle was extremely diffuse – difficult to tell where the coma ended and the sky began. At centre I could see a faint pin prick condensation. No tail observed. It was observed faintly with direct vision however averted vision was needed to see its full extent. I was delighted to finally catch Tuttle at such a faint magnitude and look forward to watching its rapid development. 17P/ Holmes and 8P/Tuttle where a real treat at this silent hour of the night. This is my 42nd observed comet.

Mag: + 10.9 – 11.0, Dia: 3′, D.C: 2

Martin McKenna’s Comet Sketches

C/2007 F1 (LONEOS)
By Martin Mc Kenna

Observation notes from Martin’s website entry:

Despite a poor sky with cloud, haze and chimney smoke along with a developing frost the sky cleared from the west on Oct 17/18th and I found the comet extremely quickly at 19.10 BST to the west and slightly south of Arcturus in the darkening evening twilight.

The coma was thin, compact, very well condensed with clearly defined edges where the coma meets the sky. It was wrapped tightly around a large white disk-like central condensation with a tear drop appendage from which a long spine ran into the tail. The coma was elongated away from the Sun and sported several fanning streamers similar in profile to a ‘shuttle cock’. The coma was a white-grey tone however no green could be seen.

The ion tail was blue, very straight, extending for 1 degree to the W of N and broadened with distance away from the Sun. Delicate long blue streamers could be glimpsed in fleeting moments of good clarity. I suspect the tail is MUCH longer than this. I was able to confirm something I have suspected since the morning of the 16th – a faint dust tail visible to the E of N leaving at a shallow angle from the coma perhaps 5′ long. The leading sunward edge of this tail is the brightest component. It will be interesting to watch its development. This is my best evening view of the comet to date.

Lost the comet to cloud so I did a little deep sky work then watched the waxing crescent Moon with earthshine set over the mountains with compact orange corona and long but faint pillar. For icing on the cake a V-shaped formation of geese flow overhead calling as they headed to the NE with bellies and wings lit orange from the town lights!.

Mag+ 6.0 Dia: 3′ D.C: 7/

Martin’s gallery of comet sketches can be found here:
Nightsky Hunter – Comet Sketches