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the big one
2024-08-27 21:48:20 -05:00
1860MmRAS..28..173A
1 73
XII. On the Apparent Projection ef Stars upon the Moon's Disk in
Occultations. By G. B. ArnY, Esq., Astronomer R~yal.
Read April 8, 1859.
A COMMUNICATION which arrives at no definite result will not, I trust, be on that account the less acceptable to the Society. Those who have ever tried to discover the causes of a perplexing phenomenon know well that the only way of proceeding with any reasonable hope of success is, to try one explanation after another, as circumstances suggest to the mind their possible applicability; and they know, also, that, next to the satisfaction of discovering a cause which really will explain the phenomenon, is the satisfaction of :finding that a conjectured cause will certainly not explain the phenomenon, and may be at once dismissed from the thoughts. Such is my position in regard to the investigation of the present paper. At the same time I must add that the examination of the expressions used by different observers in reference to the phenomenon of which I am treating has suggested to me a new explanation, in the competency of which I have great confidence, but which, from its nature, does not permit investigation of a mathematical or severely accurate character.
The attention of astronomers and of this Society has sometimes been called to the curious phenomenon of the apparent projection of a star on the moon's disk in occultations. It is established by abundant evidence that when the moon's limb is approaching a star, it sometimes (but not always) appears to go at first behind the star, so as distinctly to offer the appearance which would be presented if the star were on this side of the moon ; this appearance lasts only one or two seconds of time (perhaps more if the relative path is much inclined to the limb at the point of contact), and then the star, while thus seen on the moon's face, disappears suddenly. Numerous notices of this phenomenon are to be found in scattered observations; the largest collection, in fact the only express assemblage of
© Royal Astronomical Society • Provided by the NASA Astrophysics Data System
1860MmRAS..28..173A
174
Mr. ArnY, on the Apparent Projection of Stars
notices on projection with which I am acquainted, is in a paper by Sir JAMES SouTH, in an early volume (the third) of this Society's Memoirs.
Nearly thirty years ago I saw the phenomenon of projection myself, in great perfection. The singularity of the appearance made a strong impres-
sion on my mind, and has induced me frequently to consider the possibility
of explaining it on recognised optical principles. The only remark which appeared to lead towards a conjectural explanation was one by Sir JAMES SouTH, that in many instances a red star was the subject of projection. It seemed then not impossible that, if the light of the moon and the light of the star differed materially in refrangibility, the rays of the star (supposed the less refrangible), though actually touching the moon's body at the instant of occultation, might be so much less bent than the rays of the moon by the action of the earth's atmosphere, that at that instant the star would actually be seen lower than-the moon's limb. If, then, the occultation took place at the moon's upper limb, there would be projection of the star on the moon"s disk; if it took place at the lower limb, the star would disappear at a small distance external to the limb ; if the rays of the star were more refrangible than those of the moon, these appearances would be reversed. Here, then, was indicated a distinct criterion upon which the fate of the hypothesis must depend. It became necessary only to ascertain whether, in the instances of recorded projection, the star was uniformly higher or uniformly lower, as referred to the zenith of the place of observation, tha.n the moon's centre. If ,either of these laws held uniformly, the hypothesis would be plausible ; if neither law was sufficiently maintained, the hypothesis would be certainly false.
The arrangement of the observations with reference to this criterion involved con~iderable trouble and a large quantity of calculation, especially for the occultations which were observed before the "Angles of Position" were computed in the Astronomical Ephemerides. For these it was necessary to compute the moon's zenith distance, and to correct it for parallax, and also to compute the star's zenith distance, both with considerable approximation. The contemplation of the amount of labour and time which this operation would require has long deterred me from undertaking the work. From thi& difficulty I have, however, been delivered by the zeal of
my excellent assistant, Mr. ELLIS. At my request, Mr. ELLIS has under-
taken to examine into all the records of occultations accessible to him in
© Royal Astronomical Society • Provided by the NASA Astrophysics Data System
1860MmRAS..28..173A
upon the Moon's Disk in Occultations.
1 75
which there was notice either of proje~tion or of non-projection, to calculate the difference between the altitude of the star and that of the moon's centre, and to present the results in a form bearing at once on the object of the present inquiry. Astronomers, I am confident, will be grateful to Mr. ELLIS for this employment of his industry and ability in removing one of the obscurities of a difficult subject.
In examining the results, as prepared for me by Mr. ELLIS, I was very
much struck with the frequency of one class of remarks, which it was difficult to place under the head either of 4>projection" or of" non-projection;" namely, those which describe the star as "adhering to the limb,'' "hanging to the limb," &c. I decided, at length, upon placing these in a separate class. In the view which I shall, at the end of this communication, place before the Society, it will be seen that I consider the two classes of phenomena (projection and adherence)· to be most intimately connected.
I shall now give some general explanations on the formation of the following tables:-
The works which have been consulted are,-
The Observations of Greenwich, Cambridge, Paris, and Madras; The Notices and Memoirs of the Royal Astronomical Society,
including (with others) Sir JAMES SouTH's paper in the third volume, and the works to which it refers; The Astronomische Nachrichten; The Astronomical Journal.
All observations are included m which there is notice either of
projection or of non-projection.
,
A few instances of " hanging" or "adherence" have been omitted,
when it appeared that the duration of the occultation was very
small; and the apparent approach of the star nearly parallel to
the moon's limb..
Separate calculations have been made for the height of the star
above the moon's centre in all instances where the distance
between the places of observation exceeds ten miles, excepting
that Cambridge, Biggleswade, and Bedford, are included in the
same calculation.
© Royal Astronomical Society • Provided by the NASA Astrophysics Data System
1860MmRAS..28..173A
Mr. ArnY, on tlie Apparent Pro}ection efStars
The observations are arranged under four heads, thus distinguished:-
Class A. Where there is distinct record of observed projection. Class B. Where there is record of hanging on the limb, in a form
_which negatives projection. Class C. Where there is distinct record of no projection or
hanging. Class D. Where the accounts at the same place or in the same
vicinity are contradictory; some being of the Class A or B, while others are of the Class C. When there are records of the same observation which belong to the Classes A and B, without C, they are placed under A and B, and not under D.
As many of the observers' remarks are repeated in the same or equivalent words, I have thought it best to cite them by reference-numbers, thus:-:-
Remarks under Class A:1. Entamer le disque, indent the moon, imbedded in the limb, imbedded in the body, in die Licht-granze vollig eindrang. 2. Avancer sur la lune, advanced upon the moon's face, schien sich .einwarts zu bewegen. 3. Within the dark part, inside of the limb, within the edge, within the disk. 4. Sur le disque, on the disk, on the face, auf der Mondscheibe, sobre el disco. 5. Projection, projected upon, projete sur. 6. Vor der Mondscheibe, as if it were on this and not on the other side of the moon. 7. A travers la partie claire, as if it had been seen through a transparent moon.
Remarks under Class B :8. Sur le bord, auf dem Mondrande, upon the limb, im Mondrande, projected on the limb, bisected by the limb,
© Royal Astronomical Society • Provided by the NASA Astrophysics Data System
1860MmRAS..28..173A
upon the Moon's Disk in Occultations.
177
toucher le bord, en contact avec le bord, touching the limb, coinciding with the limb ( with words expressive of measure, or of sensible duration of time). 9. Avancer sur le disque la moitie de son image et y rester. 10. Adherente au bord, attachee au bord, adhering to the limb, attached to the limb, hung in the immersion, hang on the limb, hangt am Rande, am Mondrande zu verweilen, sticking to the limb, dancing in the limb, der Stern am Rande klebte (usually with measure of time). 11. Parcourir le bord, slide on the moon but not visible on its face. 12. Ne se detacha du bord que deux secondes apres, terns ecoule entre le contact et l'occultation, did not separate immediately, was not immediately quite detached from the limb, 2• or 3' after reappearance before there was a visible space. 13. Immersed gradually, detachee lentement.
Remarks under Class C :-
14. Besondere Erscheinungen hat Niemand bemerkt. 15. Pas aper9u sur le disque, a tres peu empiete sur le disque. 16. Keine projection, 110 projection 011 the disk, pas vu se
projeter sur le disque, limb did not appear behind the star. 17. Detachee du bord jusqu'a son entree, er verschwand als der Mondrand ihn erreichte und nicht spater, disappeared on coming into contact, came out with full brightness instantaneously and did not hang. 18. The last rays vanished instantaneously as if the centre of the star was within the moon's limb, distinctly dichotomized at the moment of occultation, bisected at the instant of disappearance, rather more than half the disk was projected instantaneously from behind the limb.
I shall now give, in a tabular form, the record of the occultations :-
RoYAL AsTRON. Soc. VOL. XXVIII.
AA
© Royal Astronomical Society • Provided by the NASA Astrophysics Data System
1860MmRAS..28..173A
Mr. AIRY, on the Apparent Projection ef Stars
Class A. With distinct Record of Projection.
No, Year and Day.
Star's Name.
--
I 1699, Aug. 18
2 1738, Aug. 8
3 1738, Oct. 2 4 1755, Sept. 25 5 1757, July II 6 1792, Mar. 27
7 ,, ,,
8 1792, Aug. 10
9 "
IO
",,
"
II 1793, Oct. 21
12 1794, Sept. 14
13 1808, Oct. 8
14 1810, May 10
15 1810, Sept. 18
16 17
"
I8II,
"
July
15
18 1811, Sept. 2
19 ,, "
20 18u, Sept. 2
21 18u, Oct. 5 22 18n, Nov. 29
23 1812, July 30
24 182.1, Feb. 6
25 " ,,
26 1821, July 30
27 " "
28 1821, Dec. I
29 1823, Mar. 30 30 1829, Aug. 21
31 " " 32 " " 33 " "
34 1829, Oct. 15
Aldebaran Aldebaran Aldebaran Aldebaran Aldebaran Aldebaran
" Aldebaran
",,
Aldebaran Aldebaran , Tauri 60 ,.1 Cancri Aldebaran
,,
y Tauri J.. Aquarii
78 Aqu"arii
y Tauri Aldebaran I'- Ceti ~ Piscium
"
Regulus
" Lal. 43324 ..- Scorpii Aldebaran
",,
"
Aldebaran
Bright
Disapp. or
Reapp.
or Dark Limb
of
Moon.
---
Place of Observation.
D B Paris
D B Paris
D B Toulouse
D B Paris
D B Paris
D D Greenwich
R B Paris
D B London
,,
"
"
,, Toulouse
"
D B Paris
D B Toulouse
D B San Fernando
D D Paris
D B Paris
D "
"
B
San" Fernando
D B Paris
"
D
"
D
" Paris
D B San Fernando
D B San Fernando
D B San Fernando
D D London
Cambridge
" R
" B Cape Frio
"
D
"
"
D Prag
D B Marseille
D B Paris
"" "
"
"
"
Liverpool
" "
D B Bedford
Observer.
Reference for
Remarks.
Reference for Account.
Height of Star above
Moon's Centre.
Moon's Radius= 1
-
+ --
-
--
-
De La Hire Le Monnier De Garipuy Pingre
4 Mern. de l'Acad., 1699, p. 151 2 Mern. de I'Acad., 1738, p. 303
7 Acad. de Toulouse, i., p. 27 5 I Conn. d. Terns, 18m, p. 336
'39 1 '423
·087 ·891
Messier Maskelyne Messier Troughton Crosley Darquier Messier Darquier Canelas Mathieu Arago Mathieu Canelas Arago Bouvard Arago
4 Conn. d. Terns, 1810,p. 339
·616
3 Gr. Obs., vol. iii., Transits, p. 205
' 174
7 Conn. d. Terns, An vii., p, :zr5
·988
3, 5 R. Ast. Soc. Mern., iii., p. 313
' 1 39
3, 5
"
"
"
"
5 Hist. Cel. Francaise, p. 403
I Conn. d. Terns, An vii., p. 216
' 139 •616
'995
5 Hist. Ce!. Franc., p. 425
•174
4 Ast. Nachr., vol. ix., p. 389
·242
4 Paris Obs., vol. i., Transits, p. 8
' 139
5 Paris Obs., vol. i., Transits, p. 19
'755
4
" " " "
·755
4 Ast. Nachr., vol. ix., p. 391
·982
5 Paris Obs., vol. i., Transits, p, 46
·906
4 2
"
Paris
Obs.,
v"ol.
i.,
" Transits,
"
p.
46
·906 ·156
Canelas
4 Ast. Nachr., vol. ix., p. 393
·995
Canelas
4 Ast. Nachr., vol. ix., p. 393
'7°7
Canelas
4 Ast. Nachr., vol. ix., p. 394
·358
Sir J. South
5 R. Ast. Soc. Mem., vol. iii., p. 304 '995
Catton
3 R. Ast. Soc. Mern., vol. xxii., p. 23' ·99o
Sir T. Brisbane 4 R. Ast. Soc. Notices, vol. ii., p. 25
·292
Riimker David
3
"
"
"
"
2 Ast. Nachr., vol. i., p. 163
·292 ·208
Gambart Mathieu Savary Arago Lassen Smyth
4 Ast. Nachr., vol. iii., p. 460
·97o
4 Paris Obs., ii., Transits, p. 197
·375
4 4 3
" " ",, "
R.
"
Ast.
"
Soc. Notices,
xvii.,
"
p.
143
'375 '375 •191
3 R. Ast. Soc. Mem., iv., p. 642
•407
© Royal Astronomical Society • Provided by the NASA Astrophysics Data System
1860MmRAS..28..173A
upon the Moon's Disk in Occultations.
1 79
Class A (continued).
No. Year and Day. Star's Name.
35 1829, Oct. 15 Aldebaran
36 37
",,
" "
"
"
38 39
,",
40 ,,
" "
"
" " "
41 "
4:,. "
"
"
"
"
43 "
"
,,
44 " "
45 " 46 "
",,
,",
"
47 "
"
"
48 "
,,
"
49 50
,",
" "
" "
51 "
"
"
52 " 53 "
",,
"
"
54 1830, Mar. 28 Aldebaran
55 1830, July 15 Aldebaran
56 1830, Sept. 6 ,,_ Ceti
57 1831, Jan, 6 94 Virginis
58 1831, Oct. 23 I' Tauri
59 1831, Oct. 23 Aldebaran
60 "
61 ,,
," ,
,,
"
62 "
"
63 "
,,
,",
64 1831, Dec. 17 Aldebaran
* 65 1836, Nov. 5 ,y Virginis
66 1845, Mar. 15
7 Magn.
67 1849, Mar. l B.A.C. 1517
68 1849, Sept. 8 ~• Tauri
69 1849, Nov. 29 B.A.C. 1391
70 1850, Aug. 2 Aldebaran
71 1855, April 18 Venus
72 1856, Sept. 18 23 Tauri
73 1856, Sept. 18 n Tauri 74 1857, Oct. 6 17 Tauri
Bright
Disapp. or
Reapp.
or Dark Limb
of
Moon.
---
Place of
Observation,
D B Bedford
,,
Biggleswade
"
" "
"
"
Greenwich
"
" "
"
" "
"
" "
"
" "
"
,,
"
"
,, Green. Hospital
" "
Black heath
" Chiselhurst
" "
,,
London
"
Kensington
" "
,,
"
"
",,
,",
"
" Islington
Woolwich
,, "
"
"
R B Dorchester, U.S.
D B Nantucket
D B Ormskirk
R D Biggleswade
D B Armagh
D B Armagh
,,
,, Cambridge
,, Biggleswade
"
"
" Bedford
"
" Munich
D B Mannheim
D B Sau Fernando
D D Parsonstown
D D Cambridge, U.S.
D B Ashurst
D B Cambridge, U.S.
D ·B Marburg
D D Washington
D B Madras
D B Madras
D B Madras
Observer.
Lee Maclear Bromhead Pond
Reference for
Re-
marks.
Reference for Account.
3 R. Ast. Soc. Mem., iv., p. 642
:,.
2
" "
" "
" ",,
"
5 R. Ast. Soc. Mem., iv., p. 637
Height of Star
above Moon's Centre.
Moon's Radius= I
1~+ --- -
• ·4o7
·407
•375
Taylor
5
"
"
"
"
·375
Henry
5
"
"
" "
·375
Richardson
5
T. G. Taylor
5
",,
"
"
",,
"
"
·375 ·375
Rogerson
5
,,
,,
"
,,
•375
Riddle
4 R. Ast. Soc. Mem., iv., p. 641
·375
Wrottesley
5 R. Ast. Soc. Mem., iv., p. 642
'375
Hussey Epps
I
,,
,,
"
"
'375
5 R. Ast. Soc. Not., i., p. 136
·375
Beaufort
3 R. Ast. Soc. Not., i., p. I 37
'375
Wilson Stratford Simms
I
"
,,
"
,,
'375
I
"
,,
,,
"
·375
5 R. Ast. Soc. Mem., iv., p. 641
·375
Prof. Barlow Barlow W. C. Bond
4 R. Ast. Soc. Not., i., p. 139
4
"
"
"
,,
5 Ast. Nach., vol. viii., p, 354
·375 ·375
'5 15
Paine
5 R. Ast. Soc. Mem., iv., p. 636
·105
Dawes
3 R. Ast. Soc. Mem., v., p. 371
·819
Mac!ear
5 R. Ast. Soc. Mem., v., p. 364
·485
Robinson
5 Ast. Nach., vol. x., p. 273
•94o
Robinson
5 Ast. Nach., vol. x., p. 273
·292
Airy
5 Camb. Obs., 1831, p. 141
·407
Maclear
2 R. Ast. Soc. Mem., v., p. 373
·4o7
Smyth
3 R. Ast. Soc. Mem., v., p. 367
·407
Lamont
4 Ast. Nachr., vol. x., p. 119
'545
Nicolai
I Ast. Nachr., vol. x., p. 92
·799
D. F. de Hoyos 4 Ast. Nachr., vol. xvii., p. 25
' 9 27
Sir J. South
7 Ast. Nachr., vol. xxiii., p. n7
W. C. Bond Snow
5 Ast. Journal, i., p. 174 5 R. Ast. Soc. Not., x., p. 16
'122 '574
W. C. Bond
5 Ast. Journal, i., p. 174
·469
Schonfeld
6 Ast. Nach., vol. xxxi., p. 249
·276
Ferguson
6 Ast. Journal, iv., p. 95
·174
Jacob
4 R. Ast. Soc. Notices, xvii., p. 17 ·588
Jacob
4 R. Ast. Soc. Notices, xvii., p. 17 ·326
Jacob
5 R. Ast. Soc. Notices, xviii., p. 29
·857
© Royal Astronomical Society • Provided by the NASA Astrophysics Data System
1860MmRAS..28..173A
180
Mr. AIRY, on the Apparent Projection ef Stars
Class B. With Record efHanging on the Limb.
No. Year and Day.
-
Star's Nnme.
Bright
Disapp. or
Reapp.
or Dark
Limb
of
Moon.
Place of Observation.
75 1755, Sept.25 A1 Tauri
D
76 1755, Sept.25 A' Tauri
D
77 1755, Sept.25 Aldebaran
D
78 79
,, "
1756, Dec. 12
eLe"onis
,,
D
80 1757, :Feb. 25 Aldebaran
R
81 ,, ,,
"
"
82 1757, Mar. 24 'l' Tauri
D
83 1757, July II Aldebaran
D
84 1758, June 9 } Cancri
D
85 1774, Apr. 14 Aldebaran
R
86 1776, Jan. 29 Aldebaran
R
87 1786, Mar. 5 20 Tauri
D
88 1793, Oct. 21 Aldebaran
D
89 1794, Sept.20 Regulus
D
90 1794, Nov. 8 Aldebaran
D
91 1794, Dec. 18 'l' Librre
D
92 93
" "
1 795, Oct. 6
~ Ca"ncri
"
R
94 1801, Mar.30 Spica
D
95 96
18"01,
"
Oct. 23
"
24 Tauri
,,
D
97 1801, Oct. 23 n Tauri
D
98 1801, Oct. 23 27 Tauri
D
99 1801, Oct. 23 28 Tauri
D
100 1805, June 10 11 Scorpii
R
IOI 1810, May 10 60 a1 Cancri
D
102 18n, Mar. I Aldebaran
R
103 "
"
"
104 18n, Mar.27 Lalande 6134
D "
105 18u, July 15 Aldebaran
D
106 18u, Sept. 2 78 Aquarii
D
107 I8II, Oct. 5 Aldebaran
D
108 1812, Jan. 23 Aldebaran
R
109 1812, Aug. 28 Aldebaran
D
IIO 1812, Oct. 22 Aldebaran
D
Ill 1812, Nov.24 Regulus
D
II2 1822, Feb. 27 19 Tauri
R
II3 1822, Dec. 25 17 Tauri
R
B Paris B Paris B Paris
,, ,,
B Paris B Paris
"
D
"
Paris
B Paris
D Paris
B Paris
B Paris
D Greenwich
B Toulouse
B Toulouse
B Paris
B Toulouse
"
D
"
Cambridge
B Paris
" Lisbon
B Greenwich
B Greenwich
B Greenwich
B Greenwich
B San Fernando
D Paris
B Paris
"
D
"
Paris
B Havannah
D Paris
B Havannah
B Paris
B Havannah
B Cambridge
B Havannah
B Dorpat
B Dorpat
Observer.
Messier Messier Messier De Barros Messier Messier Pingre Messier Le Monnier Messier Messier Messier Maskelyne Darquier Darquier Messier Darquier Hadancourt Catton Mechain Ciera Firrninger Firrninger Firminger Firrninger Canelas Arago Arago Mathieu Arago Ferrer Mathieu Ferrer Arago Ferrer Catton Ferrer Struve Struve
Reference for
Remarks.
Reference for Account.
Height of Star
above
Moon's Centre.
= Moon's Radius 1
+
-
---
II Conn. d. Tems, 1810, p. 335
II Conn. d. Tems, 1810, p. 336
IO Conn. d.Tems, 1810,p. 336
8
"
,,
IO Conn. d. Terns, 1810, p. 338
8 Conn. d. Terns, 1810, p, 339
IO
,,
"
8 Conn, d. Terns, 1810, p. 339
8 Conn. d. Terns, 1810, p, 339
8 Conn.d.Tems, 1810,p. 340
12 Conn. d. Terns, An ix., p, 436
8 Conn. d. Terns, An viii., p. 309
'799 '995 ·891 ·891 ·7o7 ·358 ·358 ·ooo ·ooo ·616 ' 259 ·669 •819
IO Gr. Obs., vol. ii., Transits, p. 384 '95 1
8 Hist. Ce!. Francaise, p. 413
'95 1
8 Hist. Ce!. Francaise, p. 425
•951
8 Conn. d. Terns, An vii., p. 217
'73 I
8 Hist. Ce!. Franc., p. 428
·993
8
"
"
IO R. Ast. Soc. Mern., :xxii., p. 19
·993 ·292
8 Conn. d. Terns, An xv., p. 432
·545
12 Conn. d. Terns, 1817, p. 318
·946
13 Gr. Obs., vol. iv., Transits, p. 85 ·500
13 Gr. Obs., vol. iv., Transits, p. 85 ·423
13 Gr. Obs., vol. iv., Transits, p. 85
' 174
13 Gr. Obs., vol. iv., Transits, p. 85 ·139
8 Ast. Nach., vol. ix., p. 375
·966
8 Paris Obs., vol. i., Transits, p. 8
• 139
10 Paris Obs., vol. i., Transits, p. 31
·731
13
IO
"
"
Paris Obs., vol. i., Transits, p. 33 ·4o7
'73 1
12 Conn. d. Terns, 1817, p. 318
·961
8 Paris Obs. vol. i., Transits, p. 46
·156
12 Conn. d. Terns, 1817, p. 318
·999
IO Paris Obs., vol. i., Transits, p, 57 ·891
12 Conn. d. Terns, 1817, p. 318
·39r
8 R. Ast. Soc. Mem., xxii., p." 22 12 Conn. d. Terns, 1817, p. 318
'423
·191
IO Ast. Nach., ii., p. 53
·921
IO Ast, Nach., ii., p. 56
·276
© Royal Astronomical Society • Provided by the NASA Astrophysics Data System
1860MmRAS..28..173A
upon the Moon's Disk in Occultations.
181
Class B (continued).
INo, Ye&r and Day.
--
Star's Name~
Bright
Disapp. or
Reapp.
or Dark Limb
of
Moon.
Il4 1822, Dec. 25 16 Tauri
II5 1822, Dec. 25 ~ Tauri
u6 1829, Oct. 15 Aldebaran
II7
us
"
"
" "
,, "
u9 120
18"30,
"
Jan.
5
Aldeba"ran
121 1830, Mar.28 Aldebaran
122. 1831, Oct. z3 Aldebaran
123 1831, Dec. 22 Regulus
R
B
R B
D B
,, "
" "
"
R
B "
R B
D B
D B
12.4
us
126
12,7
" "
" "
"
1835,
Dec".
4
" ",,
., Tauri
128 1836, Jan. 12 8 Librre
12,9 1836, Jan. 12, .,, Librre
130 1836, July 23 oScorpii
" "
" "
D" B"
D B
D B
R
B
131 132
"
1837,
Aug".2,4
136 Ta"uri
D" B"
133 1837, Sept.14 27 Piscium
D B
134 1841, May 23 ., Geminorum D D
135 1845, Oct. 18 , Tauri
D B
136 1846, June 13 c1 Capricorni D
B
137 1848, Feb. 12 Aldebaran 138 1849, Sept. 8 81 Tauri
R B D B
139 1850, Jan. 2,3 Aldebaran
140 ,,
"
"
141 142,
18"50, Aug". 2,
Aldeba"ran
R
B
" " D" B"
143 1850, Aug. 14 'Y Librre
R B
144 145
185"2, Mar".28
,,
I'- Geminorum
"
R
B "
146 1854, Apr. 4 , Geminorum R
B
l 147
148
,,
1855, Mar". 5
{ 'Y
Virg"inis
(2d Star)
,,
D
B "
149 1856, Mar.2,6 Antares
D B
149* ,,
"
,,
150 1856, July 2,5 .-2 Arietis
D" B"
151 1856, Nov. n ~ Tauri
D B
152, 1856; Nov. n 27 Tauri
D B
153 1857, May 6 Spica 154 1858, May 19 Regulus
R B R B
155
"
"
"
" "
Place of Observation.
Dorpat Dorpat South Kilworth Cambridge Prag Near Prag Boston, U.S. Boston, U.S. Aberdeen Cambridge
Bedford"
Aberdeen Cambridge Ashurst Ashurst Cambridge
Ashurs"t
Cambridge Greenwich Christiania Cambridge Altona Cambridge Greenwich
"
Cambri"dge
Cambridge
"
Madras Greenwich Ashurst Highbury Greenwich Portsmouth Wilna Madras Madras Highbury Greenwich
"
Observer.
Strove Strnve Pearson Catton David Hallaschka Paine Paine Innes Airy Whewell Smyth Innes J. Glaisher Snow Snow Challis J. Glaisher Snow J. Glaisher Main [not given] Challis Petersen Todd Dunkin Rogerson H . .Breen J. Breen J. Breen Todd Jacob Dunkin Snow Burr H, Breen Shadwell Gussew Jacob Jacob Burr Dunkin Criswick
Refer-
ence for Re-
marks.
Reference for Account.
Height of Star above
Moon's Centre.
Moon's Radius = 1
+ --- -
IO Ast. Nach., ii., p. 57
·799
IO Ast. Nach., ii., p. 57
IO R. Ast. Soc. Mem., iv., p. 643
·438
8 R. Ast. Soc. Mem., xxii., p. 27 ·4o7
IO Ast. Nachr., viii., p. 15
·os,i
IO Ast. Nachr., viii., p. 108
·052
IO Ast. Nachr., viii., p. 352
IO Ast. Nachr., viii., p. 352
IO Ast. Nachr., x., p. 2,u
IO Camb. Obs., 1831, p. 144
·2.76
8 Camb. Obs., 1831, p. 144
•2,76
8 R. Ast. Soc. Mem., v., p. 368
·276
IO Ast. Nachr., x., p. 2,11
·2.59
10 Camb. Obs., 1835, p. :1.25
·848
IO R. Ast. Soc. Mem,, ix., p. 264
10 R. Ast. Soc. Mem., ix., p. 2.64
IO Camb. Obs., 1836, p. 144
·574
10 Camb. Obs., 1836, p. 144
·574
12, R. Ast. Soc, Mem., x., p. 345
·105
IO Camb. Obs., 1837, p. 62.
·616
8 Gr. Obs., 1841, p. 75
10 Ast. Nachr., xxvi., p. 145
8 Camb. Obs., 1846, p. 79
•82,9
8 Ast. Nachr., xxvii., p. 2.31
10 Camb. Obs., 1849, P• 149
8 Green. Obs., 1850, p. 58
•2,42
IO
"
"
IO 8
Camb. O"bs., 1850, p, 2"91
•2,42, ·242 •22,5
8 Camb. Obs., 1850, p. 291 12, Camb. Obs., 1850, p. 2,91
IO Madras Obs., 1848-52,, P· 96
•998
12, Gr. Obs., I854, p. 71 12. R. Ast. Soc. Notices, xiv., p, 184
IO R. Ast. Soc. Notices, xvi., p. 2,9 ·208
8 Greenw. Obs., 1856, p. 57
IO R. Ast. Soc. Notices, xvi. p. 148
JO Ast. Nachr., xlviii., p. 343
·485
II R. Ast. Soc. Notices, xvii., p. 53 •2,08
II R. Ast. Soc. Notices, xvii., p. 53 ·788
IO R. Ast. Soc. Notices, xvii., p. 203 ·500
12 Green. Obs., 1858
IO Green. Obs., 1858
·469
·999 '515 •139
·993 ·988
·766 '545 ·839 ·588
·087 ·087 ·951 ·951 •574 •616
·906 ·906
© Royal Astronomical Society • Provided by the NASA Astrophysics Data System
1860MmRAS..28..173A
182
Mr. ArnY, on the Apparent Projection of Stars
Class C. With Denial of Projection or Hanging.
No. Year and Day.
Star's Name.
Bright
Disapp. or
Reapp.
or Dark Limb
of
Moon.
---
Place of Observation.
Observer.
Reference for
Remarks.
Reference for Account.
Height of Star above
Moon's Centre.
Moon's Radius=t
-
-+
-
-
-
-
-
156 1738, Jan. z Aldebaran
R B Paris
Le Monnier
15 Mem. de I'Acad., 1738, p. 303
'375
157 1801, Mar.30 Spica
D
B Greenwich
Firminger
18 Green. Obs. iv., Transits, p. 67
·6o2
158 18:zt, Feb. 6 ~ Piscium
R B London
Sir J. South
16 R. Ast. Soc. Mem. iii., p. 304
·53o
159 1821, Feb. 6 Lalande 1396 D
160 1829, July 25 Aldebaran
D
D London B Dorpat
SirJ. South Struve
16 R. Ast. Soc. Mem. iii., p. 305 16 Ast. Nachr. viii., p. 303
·602 ·122
161 "
"
162 "
"
," ,
163 1829, Aug.21 Aldebaran
" "
"
Preuss
"
D
Konigsberg
B" Boston, U.S.
Bessel Paine
16 Ast. Nachr. viii., p. 303 17 Ast. Nachr. viii., p. 190 16 Ast. Nachr. viii., p. 351
·12.2.
·191 ·276
164 165
" "
1829, Sept.17
"
Aldebaran
"
"
Dorchester, U.S. W. C. .Bond
16 Ast. Nachr. viii., p.351
D B Boston, U. S. Paine
16 Ast. Nachr. viii., p. 351
·276 ·695
166 1829, Oct. 15 Aldebaran
D
B Dorpat
Struve
16 Ast. Nachr. viii., p. 303
·375
167 1829, Dec. 9 Aldebaran
168 "
"
"
169 " "
"
170 1830, Mar.28 d1 Tauri
R
B Gottingen
,,
Konigsberg
"
D
" Dorpat
"
D Kensington
Harding Bessel Struve Sir J. South
16 R. Ast. Soc. Notices, i., p. 169 17 Ast. Nachr. viii,, p.191 16 Ast. Nachr. viii., p. 305 16 R. Ast. Soc. Notices, i. p. 174
·545 ' ·4o7 ·342 ·454
171 17z 173 174
" "
" "
18"30,
"
Mar.28
"
"
I'
"
Tauri
175 "
"
"
176 177
"
"
"
"
"
"
178 179
"
1830,
"
Mar.29
117 T"auri
180 1830, Mar.29 117 Tauri
" "
"
" "
"
D "
"
D
"
Kensington
" "
"
" "
,",
" "
"
D
"
D
"
Ormskirk
R
B Ormskirk
Babbage Baily Rothman Sir J. South Babbage Baily Lubbock Rothman Dawes Dawes
16 16 16 16
"
" "
"
" "
R.
Ast.
"
Soc.
Notices,
"
i.,
"
p. 174
16
"
" "
16
"
" "
16
"
" "
16 18
R.
Ast.
"
Soc.
Mem.
" "
v., p. 371
17 R. Ast. Soc. Mem. v., p. 371
·454 ·454 •454 ·105 ·105 ·105 •105 ·105 ·coo ·ooo
·940
181 1832, Feb. ro Aldebaran
182 183
"
1847,
Au"g.
19
,, x Ophiuchi
184 1848, Aug. z1 r Tauri
R B Armagh
Robinson
"
D
"
D
• Ormskirk
Dawes
Cambridge, U.S. W.C.Bond
R
D Greenwich
Main
16 Ast. Nachr. x., p. 273 18 R. Ast. Soc. Mem. v., p. 376 16 Ast. Journal, i., p. 173 17 Green. Obs. 1848, p. 67
·156 ·o35
·559 ·695
185 1851, Jan. 16 ~ Geminorum R
B Madras
Jacob
17 Madras Observ. 1848-18 52, p. 94
·559
186 1851, April 6 m Tauri
D D Cambridge
J. Breen
16 Camb. Obs. 1851, p. 417
·682
187 1852, April24 6 Geminorum D D Madras
Jacob
16 Madras Obs. 1848-1852, p. 96
·545
188 1853, Mar.28 {!} Scorpii
D B Greenwich
Dunkin
17 Green. Obs. 1853, p. 48
'883
189 1855, Mar. 5 y 1 Virginis 190 1857, Oct. 6 19 Tauri
D B Highbury D B Madras
Burr Jacob
17 R. Ast. Soc. Notices, xvi., p. 29 ·208
16 R. Ast. Soc. Notices, xviii., p. 29
·819
191 1858, May 19 Regulus
R B Manchester
Worthiugton 16 R. Ast. Soc. Notices, xviii., p.276
·891
192 " "
"
" "
"
Baxendell
18
"
" "
·891
© Royal Astronomical Society • Provided by the NASA Astrophysics Data System
1860MmRAS..28..173A
upon the Moon's Disk in Occultations.
Class D. With discordant Remarks in the same Place or Neighbourhood.
No. Year and Day. Star's Name.
193 1755, July 5 Aldebaran
194 " "
"
195 " "
"
Bright
Disapp.
or Reapp,
or Dark Limb
of
- - - Moon.
D B
,,
,,
Place of
Observation.
Paris ,,
" "
"
Observer.
Messier Le Gentil Cassini
Class of Re-
mark.
Refer-
ence for
Remark.
Reference fo1• Account.
B
8 Conn. d. Terns, 1810, p. 335
B
IO
C
17
,,
"
"
"
" "
196 1829, Aug.2.1
197 " " 198 " "
Aldebaran
" "
D B Geneva
,", "
,,
" "
Gautier Bouvard Gambart
C
16 R. Ast. Soc. Notices, i., p. I 35
A
5
A
5
"
" ,,
"
,,
"
'199 1829, Oct. 15
200
,,
201 ,", ,,
2.02.
2.03
"
"
"
"
2.04 " "
2.05
"
2.06 "
,",
2.07 2.08
"
"
" "
2.09 2.I0
,",
"
2.II
"
" "
Aldebaran
,,
" "
"
" " " " " " " "
D B Paris
,,
,,
,, ,,
"
"
" "
"
" "
,,
"
" "
"" "
" "
"
" ".,
"
" "
" ,,
" "
"
"
,,
"
"
Nicollet
A
Bouvard
C
Sir J. South C
Mathieu
B
Savary
C
Arago
C
Damoiseau B
Zach
C
Pouillet
C
Francoour
A
B. Delessert C
F. Delessert C
G. Delessert C
5 Paris Obs. ii., Transits, p. 199
16 18
9 15
,", " "
,,
"
"
"
"
" ,, "
" " ",,
18 R. Ast, Soc. Notices, i. p. 138
IO
"
,, "
17
"
" "
17 R. Ast. Soc. Notices, i., p. 139
5 17
"
,, ,,
,",
"
17 17
" "
" " " ,,
2.12, 182.9, Dec. 9 Aldebaran
213 " " :u4 " •"
" "
R
B Altona
" "
"
" "
"
Schumacher C
Nehus
C
Petersen
B
14 Ast. Nachr. viii., p. 55
14 IO
" " ",,
" "
:us 1830, Mar.2.8 Lalande 841 1 D
2.16 "
2.17 2.18
," ,
" ," ,
,, ," ,
219 " ,,
"
" "
",,
2.20
2.2.I
" "
" "
" "
"
,,
D Kensington Lord Ashley A
,,
",,
"
" " " "
"
"
" "
Sir J. South A [not named] C [not named] C [not named] C [not named] C [not named) C
5 R. Ast. Soc. Notices, i., p, 174
5 16 16 16 16 16
"
" "
"
" "
,",
" " " "
"
" "
"
" "
Height of Star
above Moon's Centre.
Moon's Radius = 1
+ --- -
·485 ·485 •485
·438 •438 ·438
"174 "174 "174 "174 "174 "174 •174 "174 "174 •174 •174 •174 ·174
•574 •574 •574
•934 ·934 "934 ·934 ·934 ·934 ·934
© Royal Astronomical Society • Provided by the NASA Astrophysics Data System
1860MmRAS..28..173A
Mr. AmY, on the Apparent Projection of Stars
Class D (continueil).
No. Year and Day. Star's Name.
222 1830, Mar. 28
223
"
"
224
225
",,
226 ,,
" "
"
227 "
"
85 Tauri
" " ",, ,,
228 1831, Dec. 22 Regulus
229 "
"
"
230 1832, Mar. 9 120 Tauri
231 " "
"
232 1857, May 6 Spica
2 33 ,,
"
"
Bright
Disapp.
or Reapp.
or
Dark
Limb of
Moon.
--
Place of
Observation.
D D Kensington
" "
"
" "
",,
" "
,,
" "
" "
"
Observer.
Class of Re-
Refer-
ence for
Re-
mark. mark.
Reference for Account.
--
Lord Ashley A [not named] C [not named] C [not named] C [not named] C [not named] C
3 R. Ast. Soc. Notices, i., p. 174
16
16 16
"
" "
"
" "
16
"
" "
16
"
" ",,
"
"
D
B Kensington Sir J. South C
18 R. Ast. Soc. Mem., v., p. 37 5
D B London
Snow
A
3
"
" "
D D Islington Simms
,,
London
Snow
"
B
8 R. Ast. Soc. Mem., v., p. 377
C
15
"
" "
R B Greenwich Main
,,
"
"
Dunkin
C
17 Greenwich Obs., 1857, p. 67
B
12
" ""
Height of Star
above Moon's Centre.
Moon's Radius = I
+ ---
•358 ·358 ·358 ·358 ·358 ·358
·276 ·276
·292 ·292
·500 ·500
An inspection of these Tables will show that there is no connexion between Projection and the geometrical circumstance of a + or - sign in the last columns. And I at once dismiss the conjectural explanation with which this paper commenced.
I have now to point out a remark which appears to me to throw light on the origin of this phenomenon.
In the record of the disappearance of .Aldebaran at the moon's bright limb on 1831, October 23, as observed by Mr. GEORGE INNES at Aberdeen (No. 122. of the preceding Tables), the following Notice is found (Astronomische Nachrichten, Vol. X., p. 2II) : -
" When Aldebaran came within about six seconds of the moon's limb it passed through the remaining distance with great rapidity, its apparent velocity becoming five or six times as great as before. It appeared to hang on the moon's limb for about five seconds of time, and then suddenly disappeared."
I need not say that, in strict language, instead of treating the approach
© Royal Astronomical Society • Provided by the NASA Astrophysics Data System
1860MmRAS..28..173A
upon the Moon's Disk in Occultat-ions.
185
as produced by the motion of Aldebaran, it ought to have been treated as
produced by the motion of the moon's limb.
Mr. INNES was, I believe, a most careful and accurate observer. And I
do not •doubt that in these his words, interpreted as I have just said, is
contained a severely correct account of the appearances which might have
been observed in other cases if the observers had been equally cool and
accurate. And the first step to the explanation of the phenomenon therefore
is this, that the disk of the moon appears suddenly to swell or to extend
itself into what was previously the dark space. And we have now to
consider whether this swelling can be explained on recognised optical and
physiological principles.
Now it must be remarked that, on the undulatory theory of light, the
image in a telescope of any luminous point (whether a star, or a portion of
the moon's illuminated surface) is not a point. The actual distribution of
light in the neighbourhood of the brightest point of the image (which agrees
perfectly with the theoretically computed distribution) is familiarly known
in the bright rings which surround the image of a star as seen in a
good telescope.
It is to be conceived that every luminous point of the moon's disk is
• accompanied with a similar system of rings ; and therefore that the aggregate
of light, produced by the aggregate of ::ill the luminous points of the moon's
disk, is not a luminous image bounded by a sharp outline at what we
consider the geometrical outline of the image, but that the geomet1;ical
outline is fringed by a band of illumination, produced by the interlacing and
superposition (not interference) of all the systems of rings. The integral
which determines the brightness is so unmanageable that I am unable
at present to assign the numerical values of the brightness at different
distances from the geometrical outline (though there would be no difficulty
in finding them by the troublesome method of quadratures) ; but as the
light from the different sources is actually superposed and aggregated,
it is certain that there must be a considerable quantity of light external
to the geometrical limb. . And when, with a very fine telescope, we see
the moon's limb very sharply defined, and apparently surrounded by
immediate darkness, we do in reality see it erroneously. Probably some
operation of the mind, under the conviction that the outline of light ought
ROYAL AsTRON. Soc. VoL. XXVIII.
BB
© Royal Astronomical Society • Provided by the NASA Astrophysics Data System
1860MmRAS..28..173A
186
Mr. AIRY, on the Apparent Projection ef Stars, g:c.
to fall in a given curve, acts on the animal faculty of sensation to incapacitate the visual organs from perceiving the fainter light beyo1i that curve.
But in the excitement and intentness of observing an occultation, the state of the sensational organization is probably much changed. And as the presumed time of the phenomenon comes nearer and nearer, the eye probably becomes more and more sensible to the faint diffused light, and the visible boundary of light extends further and further into the darkness. And this presents that appearance of rapidly increasing velocity of approach which is so graphically described by Mr. INNES.
In numerous instances, when the boundary of the moon's light has.
swelled till it touches the star, it swells no further, and the star "hangs" on the moon's limb. It seems perfectly conceivable that the mental contemplation of the relation of the positions of the moon and star which is implied in the phenomenon that is to be observed, may frequently so far act on the sensibilities that when that relation (namely, contact) is once gained, the mental effort does not make the sense more acute than is necessary, and may even somewhat relax as the denser light of the moon approaches the star.
The explanation which I have offered of these curious phenomena does in reality bring them under the general category of irradiation. But it is a kind of irradiation which has not, so far as I know, been noticed in other instances, an irradiation which sometimes exists and sometimes (under the same astronomical circumstances) does not exist, which at the same place is seen by one observer and, not by another, which sometimes remains apparently constant for at least several seconds of time and sometimes varies from instant to instant. It is probable that there is irradiation of a similar kind when the wire of a meridional instrument is placed on the moon's limb, but critical observations are yet wanting.
Royal Observatory, Greenwich, 1859, April z.
© Royal Astronomical Society • Provided by the NASA Astrophysics Data System