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The Night Sky in October

    Naturevolume 140pages581582 (1937) | Download Citation



    SUMMER Time ends on October 3 at 2h U.T. The moon is new on October 4 at 12·0h and full (the Hunter's Moon) on October 19 at 21·8h. Conjunctions between the moon and the planets occur as follows: Venus on October 2 at 4h ; Mercury on October 3 at 6h ; Mars on October 11 at 18h ; Jupiter on October 12 at 17h and Saturn on October 18 at 8h. On October 29 at 17h, Mars and Jupiter are in conjunction ; the two planets passing within 1½° of one another (heliocentric positions). On October 11 at 6h, Venus is in conjunction with Neptune. On October 15, Uranus is near the sixth magnitude star o Arietis ; the diameter of the planet is 3½˝. The satellites of Jupiter, which always offer an attractive field for observation, present a few special features this month. On October 5 at 2h 24m-27m Satellite II will be partly eclipsed by Satellite I. On October 7 a similar eclipse of these two satellites takes place at 22h 07m-24m, the magnitude of the eclipse being 0·4. On October 17, I is partially eclipsed by III at 3h 27m-36m. Appulses between II and I occur on October 12d 01·9h and October 22d l·0h, whilst a complete occultation of II by I will take place on October 25d 17·9m. On October 13, Jupiter will occult the seventh magnitude star B.D. — 22° 5100= C.D. 13939, the emersion being visible in Great Britain at 18h 34m at position angle 276° from the north point of the planet's image ("B.A.A. Handbook, 1937", p. 19). The light variation of Algol (P Persei) may be observed about 1½ hours before and after the following times: October 3d 19·6h ; 18d 03·7h ; 21d 00.5h and 23d 21·3h. The periodic comet, Encke, which was re-discovered by Jeffers on September 3 at the Lick Observatory, passes from Triangulum to Andromeda during the month. The comet, which was of magnitude 18 at the time of discovery, is still very faint, its anticipated magnitude at perihelion on December 27 being about 5·5. An ephemeris for this comet is given by Dr. A. C. D. Crommelin in "B.A.A. Handbook", p. 34 ; corrections to this ephemeris are given by L. E. Cunningham, using the positions obtained by Jeffers at re-discovery. The zodiacal light may be seen before dawn in the first part of the month when the moon is absent. In view of the present general high level of solar activity, the northern skies may also be scanned for the presence of auroral light.

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