text = "#FFFFFF" link = "#B5FF01" alink = "#DA01FF" vlink = "#CC01FF" bgcolor = "#010101"> Comet Observations

Comet Observations


To find out more about the group's in-situ cometary work, visit the Giotto Page.

Prior to the cometary flyby missions of the mid-1980's, virtually all work carried out on cometary physics was based on ground-based observations of these celestial visitors. Although our understanding of the phenomena that occur in the cometary environment has undergone a revolution since the cometary flyby missions, there is still a vast amount to learn, including the information that we can gather from further ground-based observations.

In the Space Plasma Physics Group here at MSSL, the field of cometary science which we are most interested in is that of comet-solar wind interactions. Cometary plasma can be imaged by selecting wavelengths at which the ions fluoresce following excitation by solar UV radiation. The images obtained using this method include sunlight scattered by dust in the comet's coma. Therefore, to remove this component of the images, we also obtain images in a wavelength region where there is no ion emission. By subtracting the latter from the former, we obtain images of the cometary plasma alone.


Comet 45P/Honda-Mrkos-Pajdusakova

This object made a remarkably close approach to the Earth (0.17 AU) in early February 1996 - the closest approach by a comet for 13 years. This comet was observed using the Jacobus Kapteyn Telescope on La Palma during its close passage. The following image was taken with the UK Schmidt Telescope in Australia on February 3rd 1996.


Comet Hyakutake (C/1996B2)

This comet, discovered at the end of January 1996, passed by the Earth at a distance of only 0.1 AU (beating Honda-Mrkos-Pajdusakova's distance) in late March 1996.

These images were all taken with the Radcliffe Telescope at the University of London Observatory with the help of Steve Fossey.

This first image is a true-colour image taken on the morning of March 27th - the comet was at the time exactly side-on to the Earth. The view is around 35000km across. The blue features on either side of the tail are complex structures in the C2 emission.


The remaining images were taken on the Radcliffe on Monday April 1st with a Wright CCD camera. The views are about 12 arminutes across. That corresponded to 100 000 km (the comet was 40.9 million km away, and had an elongation of 55.7 degrees - each pixel was 138.8 km across at the comet).


This first image is of dust-scattered sunlight and H2O+ emission. Plasma rays are detectable on either side of the tail. The image has been inverted and contrast-enhanced to bring out details.

This image is a close-up of the above - showing the inner regions of the dust fan.

This image is of H2O+ emission alone - an image taken through a H2O+ filter minus an image taken through a dust filter. The nucleus has rotated between the times that the two images were taken, hence the nuclear jets have been revealed - the spiral shapes around the nucleus.

Images were also obtained under service time on the Nordic Optical Telescope. Hugo Schwarz at the NOT is thanked for his help in arranging this. This image shows one of the nuclear fragements which detached from the comet's nucleus.


Images of Comet Hale-Bopp will be posted here soon.


Further Information

Comet Observations

The site to visit for the latest observational news on comet is Charles Morris' Comet Observation Page at the Jet Propulsion Laboratory.

For news of Comet Hyakutake and a multitude of images, visit Ron Baalke's Hyakutake Page at JPL.

Comets

For more information on cometary science, see the Small Bodies Node of the Planetary Data System, the Comet Page at the Los Alamos National Laboratory, and the Small Bodies Page in the Tour of the Nine Planets, which all include images and descriptions of various comets, including Halley. There is also a Comet Information Page at the Royal Greenwich Observatory.


MSSL Space Plasma Physics

MSSL Home Page

ghj@nojunk-removethis-mssl.ucl.ac.uk ace Plasma Physics Group, Mullard Space Science Laboratory,
Holmbury St. Mary, Dorking, Surrey, RH5 6NT, United Kingdom


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