Titan's Obliquity as evidence for a subsurface ocean?

On the basis of gravity and radar observations with the Cassini spacecraft, the moment of inertia of Titan and the orientation of Titan's rotation axis have been estimated in recent studies. According to the observed orientation, Titan is close to the Cassini state. However, the observed obliquity is inconsistent with the estimate of the moment of inertia for an entirely solid Titan occupying the Cassini state. We propose a new Cassini state model for Titan in which we assume the presence of a liquid water ocean beneath an ice shell and consider the gravitational and pressure torques arising between the different layers of the satellite. With the new model, we find a closer agreement between the moment of inertia and the rotation state than for the solid case, strengthening the possibility that Titan has a subsurface ocean.Comment: 11 pages, 4 figure

HST observations of the limb polarization of Titan

Titan is an excellent test case for detailed studies of the scattering polarization from thick hazy atmospheres. We present the first limb polarization measurements of Titan, which are compared as a test to our limb polarization models. Previously unpublished imaging polarimetry from the HST archive is presented which resolves the disk of Titan. We determine flux-weighted averages of the limb polarization and radial limb polarization profiles, and investigate the degradation and cancelation effects in the polarization signal due to the limited spatial resolution of our observations. Taking this into account we derive corrected values for the limb polarization in Titan. The results are compared with limb polarization models, using atmosphere and haze scattering parameters from the literature. In the wavelength bands between 250 nm and 2000 nm a strong limb polarization of about 2-7 % is detected with a position angle perpendicular to the limb. The fractional polarization is highest around 1 micron. As a first approximation, the polarization seems to be equally strong along the entire limb. The detected polarization is compatible with expectations from previous polarimetric observations taken with Voyager 2, Pioneer 11, and the Huygens probe. Our results indicate that ground-based monitoring measurements of the limb-polarization of Titan could be useful for investigating local haze properties and the impact of short-term and seasonal variations of the hazy atmosphere of Titan. Planets with hazy atmospheres similar to Titan are particularly good candidates for detection with the polarimetric mode of the upcoming planet finder instrument at the VLT. Therefore, a good knowledge of the polarization properties of Titan is also important for the search and investigation of extra-solar planets.Comment: 13 pages, 13 figures, accepted for publication in Astronomy & Astrophysic

ANALISIS KEMAMPUAN BERPIKIR KREATIF MATEMATIS SISWA DENGAN PENERAPAN PROBLEM BASED LEARNING BERBANTU GOOGLE CLASSROOM

Pembelajaran berbasis masalah dirancang agar dapat meningkatkan kemampuan berpikir kreatif siswa dengan memberi mereka lebih banyak kesempatan untuk mengeksplorasi masalah dengan berbagai solusi. Karena sejatinya berpikir kreatif sangatlah diperlukan sebagai dasar dalam menanggapi masalah yang dihadapi guna mencari solusi yang tepat. Berdasarkan penerapan model belajar Problem Based Learning berbantu google classroom di MTs Pembangunan UIN Jakarta pada materi bangun ruang, didapatkan bahwa tingkat kemampuan berpikir kreatif matematis 22 siswa MTs Pembangunan UIN Jakarta setelah proses pembelajaran dengan model Problem Based Learning (PBL) didapatkan presentase sebesar 40,91% yaitu sekitar 9 siswa pada kategori kreatif, hal ini menunjukkan hampir separuh objek penelitian berada pada kategori kreatif, sedangkan untuk tingkat kemampuan berpikir kreatif pada kategori cukup kreatif mencapai 50% yaitu sekitar 11 orang siswa, sedangkan 9,09% yaitu sekitar 2 siswa berada pada kategori kurang kreatif. Untuk kemampuan berpikir kreatif matematis jika dilihat dari masing-masing aspek dapat dikatakan sudah terbilang cukup bagus dimana di peroleh prosentase pada aspek kelancaran ini mencapai 60,23%, aspek keluwesan/fleksibilitas sebesar 64,77%, aspek orisinalitas sebesar 69,32%, dan pada aspek elaborasi sebesar 57,95

DSN observations of Titan

When using Deep Space Station (DSS)-14 in a monostatic configuration, radar observations of Titan show that Titan is a diffuse reflector with a relative radar cross section of 0.14 +/- 0.03. No hot spots were observed

Employing the model of analyze of variance in the study of regional tourism development in the Black Sea countries

All efforts to be made as to analyze the tourism activity on the Black Sea countries are justified by the tremendous potential due to the natural and cultural resources that are largely miscellaneous and of high quality. Those features turn the Romania, Bulgaria, Ukraine, Georgia and Turkey into attractive destinations for tourists. The main problem that occurs refers to the fact that the existence of some resources is not reason enough to make tourists choose such destinations. The system of the tourism statistic indicators has the purpose to characterize quantitatively and qualitatively, the process of the tourist activity and the causal relation between the factors that influence it. One of the main functions of the tourism indicators system is the characterization of the economic relation of Black Sea countries with other countries, of the efficiency of the cooperation relations in the frame of the international tourism relations. An attempt to draw up a coherent effective strategy for developing the regional tourism in the region of Black Sea in accordance with the market economy must begin with a realistic evaluation and analysis of the actual state of the tourism in the region and must have a starting point in a comparative analysis with the neighbourhood, from central and eastern Europe. A model of bifactorial variance analysis with regard to the issue of international tourism development in these countries is important for the economic and social policy, by sustaining the hypotheses about the existence of differences in average number of nights spent by foreign tourists in hotels and similar establishments between countries. This study aims at performing such evaluation using the data offered by the CESTAT Statistical Bulletin and the indicator selection and interpretation have taken into account the facilities of the actual information system. Thus, for such an analysis, data are depicted in a bidimensional matrix with r x s size and with xij elements which describe the average number of nights spend by foreign tourists in hotels and similar establishments, when one factor is on level i, i= (countries) and another on level j, j= (years). On the one hand, we analyze whether the differences recorded over the mentioned countries in the average number of night spend in hotels have statistic significance or not. In the other hand, we study whether the differences recorded over the years have statistic significance. A research into this issue can use the absolute total number of overnight stays of foreign tourists, but in order to ensure comparability of data and because there are differences between countries in number of bed-places, we proceed to turn absolute total figures in average figures. After computation for four years (1997-2000), for the countries: Czech Republic, Hungary, Poland, Romania, Republic of Slovenia and Slovak Republic and for a type I error probability a=0.05, we find the values for Fisher-Snedecor test for statistic significance of the differences between countries: Fr-1;(r-1)(s-1)=F5;15=71.776>Ftab 0.05;5;15=4.62 and between years: Fs-1;(r-11)(s-1)=F3;15=0.02

Charged particle environment of Titan during the T9 flyby

The ion measurements of the Cassini Plasma Spectrometer are presented which were acquired on 26 December 2005, during the T9 flyby at Titan. The plasma flow and magnetic field directions in the distant plasma environment of the moon were distinctly different from the other flybys. The near-Titan environment, dominated by ions of Titan origin, had a split signature, each with different ion composition; the first region was dominated by dense, slow, and cold ions in the 16-19 and 28-40 amu mass range, the second region contained only ions with mass 1 and 2, much less dense and less slow. Magnetospheric ions penetrate marginally into region 1, whereas the region-2 ion population is mixed. A detailed analysis has led us to conclude that the first event was due to the crossing of the mantle of Titan, whereas the second one very likely was a wake crossing. The split indicates the non-convexity of the ion-dominated volume around Titan. Both ion distributions are analysed in detail

Cassini: Mission to Saturn and Titan

The Cassini Mission to Saturn and Titan represents an important step into the exploration of the outerplanets. It will expand on the flyby encounters of Pioneer and Voyager and parallel the detailed exploration of the Jupiter system to be accomplished by the Galileo Mission. By continuing the study of the two giant planets and enabling detailed comparisons of their structure and behavior, Cassini will provide a tremendous insight into the formation and evolution of the solar system. In addition, by virtue of its focus on the Saturnian satellite Titan, Cassini will return detailed data on an environment whose atmospheric chemistry may resemble that of the primitive Earth. The scientific objectives can be divided into five categories: Titan, Saturn, rings, icy satellites, and magnetospheres. The key area of interest to exobiologists is Titan; the other four scientific categories will be discussed briefly to provide a comprehensive overview of the Cassini Mission