Greatest Eastern Research Articles

Interferometric measurements of zonal winds on Titan

We report millimetre observations of Titan performed with the IRAM Plateau de Bure Interferometer at the rotational frequencies of HC3N(25-24) and CH3CN(12-11). The most extended configuration of the array yielded disk-resolved emission spectra of Titan with an angular resolution of 0.6 �� . Data were acquired in February-March 2003 and February 2004 near the greatest eastern and western elongations of Titan at high spectral resolution (λ/∆λ = 5.5 × 10 6 ). Doppler lineshift measure- ments enable us to establish that the zonal wind flow is prograde in the upper atmosphere. Two different altitude regions are probed. Beam-integrated equatorial wind velocities of 160 (±60) m/s and 60 (±20) m/s are determined at respective altitudes of 300 (±150) km (upper stratosphere) and 450 (±100) km (lower mesosphere). The latter is the first direct determination of mesospheric wind speed on Titan.

Recursos estilísticos en la poesía azteca

El pueblo azteca desarrolló una cultura de enormes, casi irreconciliables contradicciones. Por un lado, realizaron sacrificios humanos tan sanguinarios que nos hacen compararlos con los pueblos más primitivos; por otro, supieron manejar y perfeccionar por lo menos dos calendarios (uno solar y otro ritual), tan complejos que, en ese aspecto, ni las más grandes culturas orientales y europeas los llegaron a igualar.

Titan’s Atmosphere and Surface from Infrared Spectroscopy and Imagery

AbstractWe have performed observations of Titan in the near-infrared since 1991, using both spectroscopy and imagery. A higher geometric albedo is observed near the Greatest Eastern Elongation than near the Greatest Western Elongation or Conjunctions. The surface is within reach for telescopes at 1.075, 1.28, 1.6 and 2.0 micron, so we simulated Titan’s geometric albedo in order to derive the surface albedo at all longitudes. Titan’s leading hemisphere appears brighter than the trailing one by 20-25% at 1.08; 1.28 and 1.6 μm, and by 35% at 2.0 μm, with spectra compatible with H2O everywhere. We have then simulated the presence of a mountain on Titan covering 50% of the leading hemisphere disk, varying its height and introducing a higher surface albedo when required. We find that a relief can not reproduce the whole geometric albedo differences observed between the two hemispheres. Some other additional component bright at 1.0 and 2.0 μm must then be invoked. Candidates are tholins or CH4, which can exist on the top of a mountain if the temperature is lower than 90 K.

Magnetic Influence of the Planets3

AN attempt to discover a direct magnetic influence emanating from the planets is described in “Magnetismus der Planeten,” by Ernst Leyst. For this purpose the author makes use of the observations taken at St. Petersburg and Pawlowsk during the years 1873–1889, and calculates the average magnetic declination for the days at which the planets are at their greatest and least distance from the earth; also for those days at which the planets are at their greatest eastern and western elongation. The numbers so obtained show certain regularities, which are considered sufficiently marked to indicate a true effect of the planetary configurations. According to the tables given, the declination is increased by 0·2 minutes of arc when Venus is nearest, and is diminished by 0′·32 when it is furthest away. Mercury acts in the opposite direction, diminishing the declination by 0′·29 when it is nearest, and increasing it by 0′·20 when it is furthest. The backbone of an inquiry like this ought necessarily to be found in a careful discussion as to how far an accidental combination of figures could account for the apparent effect. The magnetic declination is subject to so many changes which to us seem accidental, that if we take a certain number out of the whole series of daily averages, they must necessarily show deviations. The whole question then turns on the discussion whether the effects found by Mr. Leyst are sufficiently large and regular to be considered as real. This part of the subject is, unfortunately, treated in an insufficient manner, and, for this reason, the author has not in my opinion made out his case.

XIII. Note on a comparison of the diurnal ranges of magnetic declination at Toronto and Kew

Through the kindness of the Science and Art Department, South Kensington, and of Mr. Carpmael, Director of the Toronto Observatory, we have received daily values (excluding Sundays) of the diurnal range of magnetic declination at Toronto. These observations extend from 1856 to 1879 inclusive, thus forming a series of twenty-four years. Each number is the difference in scale divisions of the declinometer between the greatest eastern and greatest western deflection of the declination magnet on each day, as observed at the hours 6 a. m., 8 a. m., 2 p. m ., 4 p. m ., 10 p. m., and midnight, of Toronto mean time, one scale division of the instrument being equal to 0,,72 nearly. It is probable that such differences represent very nearly the true diurnal range. Disturbances appear to be violent at Toronto, and we have rejected a few of the most disturbed observations, embracing those which denote ranges above forty scale divisions, or 28'.8. In all 107 observations were thus rejected in the series of twenty-four years. Although this rejection has been made, it must not be supposed that the remainder are entirely undisturbed, but are only freed from the excessive influence of a few violent disturbances. We have reduced in the meantime the sixteen years extending from 1858 to 1873, in order to compare them with a similar series of the Kew diurnal declination ranges, including disturbances.