ECLIPSE COMETS
Commentary on their history and observations
© Amar A. Sharma
Nikaya Observatory, Bangalore, India
Total Solar Eclipses; the resplendent Diamond Ring… the scintillating Corona…the
inexplicable Totality…night during day… anyone who’s watched a solar eclipse would be
aware of the divine glory that is manifested.
Bright Comets; ancient celestial scimitars…vivid coma…magnificent tail…awe-inspiring
majesty…anyone who’s watched a bright, tailed, naked-eye comet would be aware of the
graceful artwork in the skies.
The term Eclipse Comets – a merger of the two – is an obscure oddity even in the general
astronomy community; only the experienced comet folk would know about comets while
eclipses. This topic was chosen because throwing a little light on the shadowy context will
bring forth to the reader a class of comets much unknown about; for very little information
exists on it by nature of the very few comets of this genre being recorded, in the first place.
We know that comets get brighter, inherently, the closer they are to the Sun. A Total Solar
Eclipse is the time when you get to see the area of sky indeed the closest to the Sun, which
only satellites like SOHO have a non-blinded eye for. There is also a category of comets
called Sungrazers which practically graze over the surface of the blazing 5500o C furnace – in
our life-time we are getting to hear of a few, like comet Lovejoy of 2011 and the famous
ISON of 2013, while the veterans would remember Ikeya-Seki of 1965.
So a total solar eclipse (totality) brings into view – against the normal laws of visibility – that
region of sky which only a non-blinded satellite had an eye for till now, by making it dark.
That means humanity, for its only time, gets to witness the careening objects near the orbof-daylight, which otherwise would never be imagined seen. That includes some possible
comets – in most cases, Sungrazers – lingering around their parent star making hair-pin
curves in their orbits. On some occasions through history, comets have been sighted during
total eclipses.
PRE-1800S
The first report of an Eclipse Comet could, in all possibility, be the comet during total solar
eclipse of July 19, 418, probably slightly south of Constantinople. Three valuable Byzantine
chronicles are known to reference the Eclipse. Philostorgius (born around 363) described
the eclipse and that stars were visible. In his sketch he described a comet; other sources
also described the comet in 418. Before this a similar case had been mentioned by Seneca of
Rome. The next known record comes only 14 centuries later, in the 1800s.
Meanwhile, M. G. Bigourdan, in his book Les Eclipses de Soleil, in 1905 describes 4 Eclipse
Comets, including those of 418 AD and April 30, 462 BC. Possidonius reported of seeing a
comet during the eclipse of April 30, 462 BC. There are no other references found yet.
Seneca relates from Possidonius that a comet was seen when the Sun was eclipsed, which
had before been invisible by being near that luminary.
There is a sketch of the eclipse of August 18, 1868 by Bullock in Manila. There is a comet-like
object, starting from the edge of the Sun and Moon. The sketch can also be found in the
book of P. Secchi, Les Eclipses de Soleil, in 1870 but none of the eclipse observers reported a
comet.
1882
One of the most famous of eclipse comet was the one visible in May 1882’s total eclipse;
also the first comet discovered on the photographic plate of a total solar eclipse.
Astronomers had gathered in the region of Upper Egypt as a total eclipse of the sun was
predicted to occur on May 17, 1882. The eclipse was observed by Lockyer, Ranyard &
Schuster of England, Tacchini of Italy, and Trépied, Thollon & Puiseux of France. Observation
place was Sohag, at the Nile, about 100 kilometres south of Siout in Egypt.
Arthur Schuster photographed the eclipse. About the middle of totality, a luminous streak
was observed near the sun. Trépied made a sketch of the corona. On his sketch there are
some curved lines; Trépied noted the 'feature' to the right of the sun at a zenith angle of
nearly 90°. Only when the pictures of Schuster were developed, Trépied noticed what he
had drawn. They both, individually, had recorded the coincidental perihelion passage of a
Kreutz sungrazer comet in the field.
Photographs of the eclipse revealed that the comet had moved noticeably during the 1m50s
eclipse – as would be expected for a comet racing past the Sun at almost 500 km/s. To
Trépied the idea of this object being a comet did not cross his mind until he saw the first of
Schuster's photographs almost an hour after the eclipse, continuing, “The brightness of the
comet appeared to one to be of the same order as that at the exterior parts of the corona”.
A. Schuster and Captain W. de W. Abney (both members of an English team) said, “The
nucleus is exceedingly well and sharply defined, the tail is somewhat curved; it did not point
toward the sun's centre, but in a direction nearly tangential to the limb. The extent of the
tail was roughly two-thirds of a solar diameter”.
The various eclipse parties met after the eclipse and jointly agreed to name the comet as
Comet Tewfik, in recognition of the Khedive of Egypt, Tewfik Pasha's generous hospitality in
welcoming the astronomers.
In the same year (1882), there were 2 bright comets visible: Comet Wells and the Great
September Comet. Comet Wells was even visible during the period of the Eclipse Comet.
Initial investigations suggested this eclipse comet was probably Comet Wells which had
been well observed during the previous couple of months; however, calculations showed
Wells would not have been in the proper position and would have been much fainter. These
two 1882 bright comets should not be now confused with the Eclipse Comet. For the orbit
of this sungrazer, Dr. Brian Marsden conjectured that the eclipse comet was associated with
C/1880 C1.
Credit: Wikipedia
Source: Total eclipses of the Sun; Mabel Loomis Todd
1948
The Eclipse Comet of 1948 approached from behind the Sun, passing perihelion unseen on
October 27 at 0.14 AU. On November 1, during a total eclipse of the Sun – totality time
lasted only 45 seconds – observed from Nairobi, the comet suddenly became visible as a
brilliant object some 105' from the Sun’s center and showing a very strongly curved tail
visible for at least 4 degrees on photographs. The comet was visible very briefly into the
partial phase of the eclipse, but soon became lost against the brightening sky.
The Times of November 2 in the report of the eclipse from its correspondent from Nairobi
stated that a bright comet, with a long tail, was seen both by the crew of an RAF aircraft and
by observers on the ground. They observed the comet only 4 lunar diameters from the Sun.
The head, it was stated by one amateur astronomer, was still visible a few seconds after the
Sun began to emerge.
It was rediscovered on November 4 by Captain Frank McGann from an aircraft and on the
following mornings by numerous people as the bright long-tailed object emerged from the
rays of the dawn. A cable received by Dr R. d'E Atkinson, leading the Royal Observatory
expedition, reports photographic confirmation of the Eclipse Comet 1948 saying it was 93'
from the centre of Sun in position angle 226o, and was very bright, with a tail. The comet
was also believed to have been photographed by Dr Atkinson in Nairobi (even though he
reveals he was not in Nairobi but present at Mombasa) [his details to follow below]. It was
next seen in Australia, by an airline pilot, Capt. Thomson, while flying from Perth to
Adelaide, presumably on November 6. Since then observations were received, through the
IAU CBAT, by J.S. Paraskevopoulos (Boyden Station of Harvard Observatory, Blomfontein,
South Africa), and by Wood and Gottlieb (both at Mt Stromlo, Canberra, Australia). All
sources estimated the comet as 2nd magnitude and the Press reports gave the tail as 20o
long. The official discovery of this comet was announced on November 8; the first message,
through the Harvard College Observatory, came from Paraskevopoulos. Within a day or two,
messages came in reporting that the comet was seen by two observers in Mexico at the
National Astrophysical Observatory at Tonanzintla, and by four persons in Argentina who
notified the Cordoba Observatory. The dates of observations from Mexico and Argentina
were not given. Wood’s observation came in on November 8. The new comet was first seen
from Mt Hamilton on the morning of November 9. On the following mornings, its westward
motion took it farther from the Sun, and the position improved, although the brightness
diminished. A good series of photographs was obtained with the 20-inch Carnegie
astrograph by Messrs. Shane and Wirtanen. Marked changes in the structure of the tail are
apparent in photographs from November 12, 13 and 14.
Eclipse Comet 1948 X1 as photographed by Dr R. d'E Atkinson in Nairobi, Kenya, on
November 1, 1948. Picture taken in white light.
Credit: A note on eclipse comets; paper by M. Solc, Charles University, Prague
The comet had been observed after the eclipse till 3 April 1949 in the Southern Hemisphere.
It was a Southern Hemisphere object not well seen by people in the Northern Hemisphere.
However, at some time it started becoming visible from the British Isles low on the southeast horizon in the twilight before dawn.
By mid-November, its tail extended some 30o as observed with the naked eye. The comet
faded below naked-eye visibility around December 20.
The only observations of Comet 1948l made at Royal Observatory, South Africa, were two
series of photographs taken with the Astrographic Refractor to which was attached the
Wide Angle Lens Camera; first series had relatively short exposures intended to furnish
accurate positions of the comet, the second series had rather long exposures intended to
register any changes that might take place in the structure of the comet's head and in the
beginning of the tail. Notes were made of the visual appearance of the comet on each
morning that photographs were taken, at the Royal Observatory. For the first few mornings,
it was reported, Comet 1947l was a magnificent object even though dawn was already
breaking. In general appearance, it resembled the usual pictures of Comet Halley 1910. The
tail was fairly narrow, about 12o long and brighter on the northern than on the southern
side. The nucleus and head were distinctly orange in colour for the first few days but
gradually changed to the usual milky-white colour, and the nucleus began to stand out more
clearly from the surrounding coma. After the first week, visual observations of the tail were
restricted by the Moon, but even so, some 5o of the tail could be seen. At the end of
November with the Moon out, the comet was still a naked eye object with nearly a degree
of its tail visible.
However, and interestingly, the eclipse comet of 1948 was not a Sungrazer. This is the only
eclipse comet that was observed outside of the eclipse, following discovery, and a definitive
(non-sungrazing) orbit had been computed.
The comet was also discussed about in the meeting of the Royal Astronomical Society
(R.A.S) on November 12, 1948, a Friday evening, under the presidency of Prof W.M.H.
Greaves, F.R.S. It was in the meeting Dr Atkinson revealed, “The comet, though very bright,
was not visible at Mombasa, where we were (98% totality), but several newspaper reports
from further north referred to it; they did not sound very convincing. A photograph was
published, but as printed it did not actually show the comet; the accompanying description
was also based on an error, as I later learnt. On the journey to Nairboi, sixty hours after the
eclipse, I spoke to an eye-witness, whose account disagreed with that in the paper. It was
not until I had seen the photographs taken by the R.A.F. at Nairboi (taken at 13,000 feet just
within and just outside the shadow), and had found that they agreed with eye-witness
reports at both places, that I realized it must have been a comet; I then made a very rough
measurement of its place on the R.A.F. film, and telegraphed Dr Merton. The first slide
shows a picture very much enlarged from a hand-camera snapshot also taken by a member
of the crew. The tail is clearly visible; visual observers all agreed that it extended downwards
until it reached either clouds or the horizon, and it must have been twenty degrees long, at
least. One can see enough indications of curvature to make it seem that it is convex to the
west; I therefore included in my cable a guess that the motion would be westwards, and this
has proved correct. The comet must certainly have been very bright; these pictures were
taken with an aperture of f/5.6 and an exposure of 1/300 of a second; moreover the head
was visible for some 5-10 seconds after the end of totality. It must certainly have been
brighter than Venus”.
Comet 1948 XI (1948l) sketched by Charles F. Capen (noted lunar and planetary astronomer)
with 7x35 binoculars and a 3.5-inch f/10 reflector, November 10, 1948, at 5:30 a.m. CST. On
a protective wrapper around the drawing, Capen penned, “My first comet as an amateur
astronomer”.
Credit: David J. Eicher library, Astronomy.com article
David Seargent, in his book 'The Greatest Comets in History' mentions of an amusing
account. “In the late 1980s, a short article in the journal of an Australian Astronomical
Society recounts an experience of the writer who, late one afternoon at the end of October
1948, was sitting on the porch of his house watching the Sun set when his attention was
caught by a bright comet with a tail next to it. He recalled that a dense layer of haze, plus
the Sun’s low altitude, made it possible to look in the direction of the Sun without being
dazzled and it was because of this that he noticed the presence of the comet. Thinking that
such a bright object would certainly be known to astronomers (!), he did not report his
sighting - at least, not until some 40 years later! Unfortunately, the details of this
observation have become lost, but it seems to be genuine and probably took place on the
evening of October 31”.
ECLIPSE-COMET MASQUERADERS: 1860, 1871, 1893 and 1980
A. Cowper Ranyard, Esq. calls attention to an examination on the photographs of the eclipse
of December 12, 1871 as “the dark and partially opaque details of the photographs which
correspond to the luminous details of the corona, where this was a bright or transparent
structure; and bright spots, lines, or patches had always been regarded as photographic
defects, and consequently but little attention had been paid to them”. The photograph was
not observed until after nearly a year had been spent cataloguing the details. He described
the structure as, “This circular and concentric structure is so different from all other forms
traceable among the dark details of the corona, that I was loath to accept it as being in any
way connected with the Sun”. However, Ranyard does not explicitly call it a comet, but “the
structure must be either due to some dark body in the corona, or to some semi-transparent
body situated between us and the corona, at a great distance from the Earth”.
Structure in the corona examined by A. Cowper Ranyard, Esq. during total solar eclipse of
December 12, 1871
Credit: Monthly Notices of the Royal Astronomical Society (MNRAS), Vol. 34
The total eclipse of 1893 brought in another eclipse 'comet'. The object was photographed
by J.M. Schaeberle of the Lick Observatory during totality of April 16, 1893. While in Mina
Bronces in Chile, Schaeberle used a 40-ft focal length eclipse camera with a 5-inch objective
lens to obtain seven large scale (18x22 inches) plates of the corona during totality with
exposures ranging from 0.25 seconds to 32 seconds. A feature observed on the 32s
exposure plate resembled a comet in some of its aspects. Plates obtained by the English
expeditions to Brazil and Senegal established the outward motion of the structure.
Since the 'comet' was not observed outside of the eclipse, it was not possible to calculate an
orbit and determine the time of perihelion passage. Thus the feature – looking like a coronal
extension – is generally referred to as the Eclipse Comet of 1893. However, this comet was
not noticed visually by any of the observers along the eclipse path, nor was it noted by any
photographic observer other than Schaeberle. It was neither reported by observers in the
northern hemisphere on nights prior to the eclipse nor reported by anyone following the
eclipse. Also, the 'comet' was reported to change its magnitude during the eclipse, from -1
magnitude during observations in Chile to a point where it was 'very faint' or 'would have
escaped observation altogether' on the plates taken from Senegal taken 2h 35m later.
Schaeberle called attention to this comet at the World’s Fair Astronomical Congress in
August 1893.
A revaluation of the eclipse comet of 1893 later suggested that the 'comet' was, in fact, a
disconnected Coronal Mass Ejection (CME) from the Sun. It seems likely that the comet
would not have been identified as an extra-coronal entity had Schaeberle not captured it on
the longest exposure (32 seconds) plate made with the 40-ft focal length camera. It is
believed candidate disconnection events – mimicking eclipse comets – were also observed
during total eclipses of July 18, 1860 and March 16, 1980. The appearance of an eclipse
'comet' of 1860 [the first ever solar eclipse photographed] was noticed by Prof Winnecke,
and a drawing of it published. And the 'comet' photographed by Schaeberle during 1893
bears an interesting resemblance to the disconnection event reported by Illing and
Hundhausen during the total solar eclipse of 1980.
A consideration of the sunward pointing tail or anti-tail exhibited by the 1893, which was
also reported (by Schaeberle), comet seems anomalous, and contrary to both observed and
expected behaviour of cometary dust ejecta.
The magnitude change reported over the short time span constitutes unusual behaviour for
a comet but serves more understandable behaviour for a CME. At that time, it was also not
known if the corona could change over short time scales.
Kreutz (1901) compared the measured positions of the 1893 eclipse 'comet' with the orbits
of sungrazing comets 1843 I (Great March Comet) and 1882 II (Great September Comet) and
concluded that the 1893 comet was almost certainly not a sungrazer. At least six and
probably seven of the eclipse comets observed later (including those observed by the
satellite SOLWIND) were Kreutz sungrazers. The 1893 'comet' event almost certainly was
not.
It is interesting to note that all three of the candidate disconnected mass ejections observed
at the time of a total eclipses in 1860, 1893 and 1980 occurred during years of maximum
sunspot number -- average yearly sunspot numbers for those years being 95.8, 85.1 and
154.6 respectively. One obvious reason for this result is that the CME occurrence rate may
vary directly with sunspot number. It is now believed that the comet was actually a transient
feature of the solar corona that had some non-radial motion, approximately at 30 km/s.
PROFESSIONAL SEARCHES
A total solar eclipse is such a gripping sight by itself, an observer remains transfixed with an
electrifying current zip-zapping head to toe. Which eye – even a layperson’s – would want to
be unleashed from the sight! So, ultimately, who would care about Comets while Eclipses?
Quite a few professional astronomers from universities, under the banner of "special
projects during a total solar eclipse" would go out and look at the region around the Sun in
search of undiscovered, new objects. That is their job. Known professional photographic
comet searches were made during 4 eclipses in the 20th century: 1963, 1966, 1968 and
1970.
James Gibson of Van Vleck Observatory (Wesleyan Observatory) reported that during the
solar eclipse of November 12, 1966, three modified K37 aerial cameras were operated
aboard a four-engined jet aircraft to back up ground based comet search. The longest
exposures were 1 second in white light (3900A - 7000A). The NC-135 aircraft, operated by
the US Air Force was flown for 200 seconds in the moon's shadow. In all, 110 exposures
were made, with a limiting magnitude of +2.5 in the eclipse. No comets were observed.
Henry Courten and Richard Genberg of Adelphi University report of a four-man team, under
a NASA grant, operated a ground based photographic station in Bage in southern Brazil at
the centreline of the eclipse path on November 12, 1966. Specially modified aerial cameras
with coverage out to 40 solar radii were used with interference filters and 8x10 inches glass
plates to search for small bright comets proximate to the Sun. Although a thin atmospheric
haze resulted in a rather high level of sky background, star images to magnitude +7 were
recorded, along with excellent images of the coronal structure. The comet search
equipment was follow-on to the initial search conducted by Dr B. Donn and Dr Francois
Dossin during the July 20, 1963 total eclipse.
During the total solar eclipse of September 22, 1968, the search for small, bright comets
near the Sun was continued. The initial attempt by Donn and Dossin in 1963 yielded one
nonstellar image whose origin was thought to be cometary. An intensive photographic
search conducted in 1966 indicated the possibility of ten nonstellar objects within 10 solar
radii. These preliminary findings were presented at the AAS Williams Bay meeting in 1967.
Since that time, confirmation of seven of the ten images had been reported by an
independent observer. Further, most of the data from photographic and photoelectric
observations made in Siberia during the 1968 eclipse were reduced and there was good
evidence for nine nonstellar images originating in the near-angular vicinity of the Sun.
During the March 7, 1970 total solar eclipse, a search for comets near the sun was made.
Wide field coverage (40ox40o) of the general sky area was obtained using a Hasselblad
camera, with an 80-mm lens operated at f/2.8. The near solar area was observed with a 7inch Questar-Hasselblad combination. A total of 18 frames were exposed during the period
of totality. Stars down to limiting magnitude +3.5 were identified during post-eclipse
evaluation of the exposures. There were no comets brighter than this limit visible on any of
the frames.
A report by H.C. Courten, D.W. Brown and D.B. Albert mentions ten years of photographic
observations covering 6 total solar eclipses have yielded data which indicate the presence of
one or more relatively faint objects with 20 solar radii.
Though not an eclipse comet search, a Czechoslovak expedition to Poland in 1954 took wide
field pictures in the white light of the eclipsed Sun on June 30 in order to estimate the
brightness of Comet 2/P Encke.
Similarly, the last occasion was the very bright comet C/1995 O1 (Hale-Bopp) for which E.
Markova, P. Kotrc and their expedition succeeded to take pictures of this comet during the
total solar eclipse on March 9, 1997. Since the comet had the solar elongation of 40o, the
picture was taken with a wide field camera. This comet was so exceptionally bright at night
that it was recognized even on the very bright sky above the snow-covered Siberia. But the
comet was rather faint to see during totality. Many missed the opportunity seeing an eclipse
and a comet at the same time. Hence, paradoxically, the comet was found on the picture
only much later, when the colour slide was projected on the screen. Many observers where
clouded out, mainly in Mongolia, whereas Siberia and China had clear views.
AMATEUR SEARCHES
However, one extravagantly rare, handful of comet-crazy amateurs would plan to hunt for
Eclipse Comets; they know they have to put a memorable total eclipse, as it is it lasts only
handful of minutes, at stake. They would head out during total solar eclipses only for
hunting eclipse comets, of course, after getting a decent brief view of the total solar eclipse
and being content with the premature end of their solar sighting to commence comet
hunting. It is 'not' surprising to hear from a comet hunter of them attempting to scan the
totality skies for their ardent love: comets.
When asked David Levy, the US comet hunter, if he has performed the art of hunting eclipse
comets, he has to say, “Yes, I have spent some time during each of the ten or so total
eclipses of the Sun that I have seen, searching for comets near the Sun”. But he considers it
extremely unlikely that we may ever find one visually now with the solar satellites keeping a
vigil.
When asked David Seargent, the Australian comet hunter, he too had plans, “I did intend to
do a quick binocular search during the eclipse of 1976, but unfortunately that one was
clouded out by an inconveniently placed thunderstorm, so nothing could be done. From
memory, I think that most of the eclipse path had some cloud, so even the sites that saw the
eclipsed Sun probably did not have clear skies enough to do any meaningful comet hunting”.
Seargent, too, has thoughts in accordance, of these days with SOHO and STEREO in full
swing, it would be very unlikely to find an eclipse comet that had not already been picked
up. He mentioned William Bradfield might have had plans to do a (photographic?) search
during that same eclipse, of 1976, from a different site.
When asked Shigeki Murakami, the Japanese comet hunter, he also had plans, “I toured the
total solar eclipse at China in 2009. It was the first time I tried to observe total solar eclipse
but it was raining. At that time I had a plan to comet hunt during totality. The duration of
the total eclipse was 5 minutes and 50 seconds and I wanted to spend at least 3 minutes to
comet hunt. The next opportunity was November 2012 in Australia. I actually observed the
total eclipse for the first time but the duration of totality was only 2 minutes. So I did not
have a plan to comet hunt at that time due to short duration of the total eclipse”.
When asked Dr Kazimieras Cernis, the Lithuanian comet hunter, he performed it too, “I
observed a total solar eclipse two times: in July, 1990 (Tallinn, Estonia) and in August 1999
(Sumeg, Hungary). First time I only photographed the Sun, and second time I photographed
the Sun and did comet hunting around the Sun with a 7x50mm binoculars”.
Patrick Moore, too, writes of the same in his book "Stargazing: Astronomy Without a
Telescope; second edition", “I have been lucky enough to see eight totalities, and each time
I have searched for comets, but with no success”.
The author witnessed his first total solar eclipse in 2009 [longest for 21st century and the
last one for the century in India] in North India at Varanasi, the city of Holy Ganges. He too
was mindful to devote time (planned from prior) and could casually scan the sky 15 seconds
for eclipse comets with a 10x50 binoculars (it being his first inexperienced attempt), amidst
the grand sight of totality lasting 3.5 minutes. Nevertheless, the author plans on 'sacrificing'
the upcoming total solar eclipses in priority to hunting eclipse comets even given the nonexistent chances of success, for what comets mean to him.