Dörfel Mountains. Visible on the Moon’s S.S.E. limb. They exhibit three peaks, which, on the authority of Schröter, rise to more than 26,000 feet above the average level of the limb. The loftiest mountains on the Earth are in the Himalayas—a range of immense extent to the N. of India. The three highest peaks are Mount Everest (29,002 feet), Kunchinjinga (28,156 feet), and Dhawalagiri (28,000 feet). The only lunar mountain more elevated than these is that of the Leibnitz range, which, as we have already stated, ascends to fully 30,000 feet.
Aristarchus and Herodotus at sunrise. 1884, Jan. 9, 8h 30m to 10h 30m.
(T. Gwyn Elger.)
Apennines. A vast chain of mountains, extending over more than 450 miles of the lunar surface. Huygens is the most elevated peak, rising to more than 18,000 feet, and on its summit it shows a small crater. There are several other very lofty peaks in this range. The Sun rises upon the westerly region of these mountains at the time of first quarter, and the peaks and ridges, with their contrasting shadows, create a gorgeous effect just within, and projecting into the darkness beyond, the terminator. There is an immense amount of detail to be studied here, and much of it is within the reach of small instruments.
As the lunar mountains and craters are best seen near the terminator, it may be useful to give a table of objects thus favourably placed between the times of new and full Moon. The summary may assist the student, though it does not aim at exactness, only even days being given.
Objects near the Terminator.
| Moon’s age in days. | |
|---|---|
| 2 | Mare Crisium, Messala, Sunrise on the Mare Humboldtianum,Langrenus, Vendelinus, Condorcet,Hansen, Gauss[17], Hahn, Berosus. |
| 3[18] | Craters in Mare Crisium, Taruntius, Picard, Fraunhofer,Vega, Pontécoulant, Cleomedes[19], Furnerius,Petavius, Endymion, Messier[20], Vlacq. |
| 4 | Mare Nectaris, Macrobius[21], Proclus, Sunrise onFracastorius, Rheita and Metius with the interveningvalley, Guttemberg, Colombo, Santbech,Mountainous region W. of Mare Serenitatis,Hercules, Atlas. |
| 5 | Palus Somnii, Plana, Capella, Isidorus, Polybius,Piccolomini, Vitruvius, Littrow, Fabricius, Posidonius,LeMonnier, Theophilus, Cyrillus, Catharina,Hommel. |
| 6 | Tacitus, Maurolycus, Barocius, Dionysius[22], Sosigenes,Abulfeda, Descartes, Almamon, Gemma Frisius,Plinius, Ross, Arago, Delambre, Aristoteles,Eudoxus, Julius Cæsar, Linné, Menelaus. |
| 7 | Ptolemæus, Albategnius, Manilius[23], Hyginus and its rill-system, Hipparchus, Autolycus, Aristillus,Cassini, Alpine Valley, W. C. Bond, Walter,Miller, LaCaille, Apennines, Triesnecker and therills W. of it. |
| 8 | Mare Frigoris, Arzachel, Alphonsus, Alpetragius, Bode, Pallas, Archimedes, Plato, Maginus[24],Mösting[25], Thebit, Saussure, Moretus, StraightWall, Lalande, Kirch. |
| 9 | Tycho, Clavius, Eratosthenes[26], Stadius and the craters running to N.E., Timocharis, Pitatus, Gruemberger,Teneriffe Mountains, Straight Range[27],Formation W. of Fontenelle[28], Gambart. |
| 10 | Sinus Iridum, Copernicus, Hesiodus and the rill to E., Wilhelm I., Longomontanus[29], Heinsius,Pytheas, Lambert, Helicon, Wurzelbauer. |
| 11 | Bullialdus, Campanus, Mercator, Reinhold, Riphæan Mountains, Hippalus, Capuanus, Blancanus, TobiasMayer. |
| 12 | Mare Imbrium, Gassendi[30], Aristarchus and sinuous valley to the N.E., Herodotus, Marius, Flamsteed,Letronne, Schiller, Mersenius, Doppelmayer. |
| 13 | Schickhard, Wargentin, Grimaldi, Byrgius, Phocylides, Hevelius, Seleucus, Crüger, Briggs,Segner, Sirsalis. |
| 14 | Mare Smythii, Bailly, Inghirami, Bouvard, Riccioli, Olbers, Hercynian Mountains, Cardanus, Krafft,Cordilleras[31], Pythagoras[32]. |
Occultations of Stars.—Among the various phenomena to which the lunar motions give rise none are more pleasing to the possessors of small telescopes than occultations of stars. Several of these occurrences are visible every month. If the amateur has the means of obtaining accurate time, he will engage himself usefully in noting the moments of disappearance and reappearance of the stars occulted. This work is efficiently done, it is true, at some of our observatories, and therefore little real necessity exists for amateurs to embark in routine work which can be conveniently undertaken at establishments where they have better appliances and trained observers to use them. The mere watching of an occultation, apart from the registry of exact results, is interesting; and there are features connected with it which have proved exceedingly difficult to account for. The stars do not always disappear instantaneously. On coming up to the edge of the Moon they have not been suddenly blotted out, but have appeared to hang on the Moon’s limb for several seconds. This must arise from an optical illusion, from the action of a lunar atmosphere, or the stars must be observed through fissures on the Moon’s edge. The former explanation is probably correct; for it has happened that two observers at the same place have received different impressions of the phenomenon. One has seen the star apparently projected on the Moon’s limb for about 5 seconds, while the other has witnessed its sudden extinction, in the usual manner, as it met the Moon’s edge. New observations, made with good instruments and reliable eyes, and fully described, will doubtless throw more light on the peculiar effects sometimes recorded.
Visibility of the new and old Moon.—It is an interesting feature of observation to note how soon after conjunction the Moon’s thin crescent is observable with the naked eye. A case has been mentioned in which the old Moon was seen one morning before sunrise and the new Moon just after sunset on the next day. At Bristol, on the evening of March 30, 1881, I saw the new Moon at 7h 10m, the horizon being very clear in the west. She was then only 20h 38m old. On June 4, 1875, I observed the Moon’s crescent at 9h 10m, or 22h 49m after new Moon. Dr. Degroupet, of Belgium, saw the old Moon on the morning of Nov. 22, 1889, between 6h 47m and 7h 22m G.M.T., or within 18h 22m of the time of new Moon.