34 resultados para Meteors


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Películas ganadoras de los Premios de Vídeo Escolar 1995

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Describe los orígenes y la composición de los asteroides, cometas y meteoritos, así como su impacto,literal, en la historia de nuestro planeta, y lo que nos dicen sobre el sistema solar, y sobre lo que los científicos aprendieron de los efectos de un cometa en la superficie de Júpiter. Tiene glosario, bibliografía y direcciones internet.

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This paper presents evidence of an apparent connection between ball lightning and a green fireball. On the evening of the 16th May 2006 at least three fireballs were seen by many people in the skies of Queensland, Australia. One of the fireballs was seen passing over the Great Divide about 120 km west of Brisbane, and soon after, a luminous green ball about 30 cm in diameter was seen rolling down the slope of the Great Divide. A detailed description given by a witness indicates that the phenomenon was probably a highly luminous form of ball lightning. An hypothesis presented in this paper is that the passage of the Queensland fireball meteor created an electrically conductive path between the ionosphere and ground, providing energy for the ball lightning phenomenon. A strong similarity is noted between the Queensland fireball and the Pasamonte fireball seen in New Mexico in 1933. Both meteors exhibit a twist in the tail that could be explained by hydrodynamic forces. The possibility that multiple sightings of fireballs across South East Queensland were produced owing to fragments from comet 73P Schwassmann-Wachmann 3 is discussed.

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Resumen: La identificación de los fenómenos considerados sublunares en la Antigüedad a partir de la terminología latina es particularmente dificultosa. Nuestra propuesta es considerar los términos que aparecen en las enumeraciones de Plinio y Séneca tomando como parámetro de referencia la nomenclatura astronómica moderna y como hipótesis la de que las observaciones antiguas, por personas de gran capacidad de observación en un cielo sin contaminación lumínica pueden compararse a las que podemos obtener hoy a través de la astrofotografía. La conclusión es que, dado que en la Antigüedad grecolatina cada fenómeno se reportaba con la misma fórmula descriptiva, es posible determinar la equivalencia entre los términos romanos y los actuales (cometas, meteoros, etc.), como paso previo a adoptar una decisión traductiva, ya sea que los consideremos términos científicos o culturalmente específicos.

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Wydział Fizyki:Instytut Obserwatorium Astronomiczne

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We present observations of a statistically-significant number of Jupiter-family cometary nuclei as part of SEPPCoN (Survey of the Ensemble Physical Properties of Cometary Nuclei). We present preliminary results on distributions of albedos and shapes.

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We present VLT+VISIR mid-IR observations of fast-rotating near-Earth asteroids. Diameters and albedos are determined with thermal models. These NEAs may have unusual surface properties, e.g. from regolith transport/stripping due to the YORP effect.

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We describe the discovery of comet-like activity in main-belt asteroid (300163) 2006 VW139 (later re-designated as Comet P/2006 VW139) by Pan-STARRS1. We also detail follow-up photometric, spectroscopic, and dynamical analyses of the object.

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The Yarkovsky (orbital drift) and YORP (altering spin state) effects are important mechanisms governing the evolution of asteroids. We have included global-selfheating into a new model and demonstrate that it significantly affects YORP predictions.

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We present the study of absolute magnitude (H) and slope parameter (G) of 170,000 asteroids observed by the Pan-STARRS1 telescope during the period of 15 months within its 3-year all-sky survey mission. The exquisite photometry with photometric errors below 0.04 mag and well-defined filter and photometric system allowed to derive H and G with statistical and systematic errors. Our new approach lies in the Monte Carlo technique simulating rotation periods, amplitudes, and colors, and deriving most-likely H, G and their systematic errors. Comparison of H_M by Muinonen's phase function (Muinonen et al., 2010) with the Minor Planet Center database revealed a negative offset of 0.22±0.29 meaning that Pan-STARRS1 asteroids are fainter. We showed that the absolute magnitude derived by Muinonen's function is systematically larger on average by 0.14±0.29 and by 0.30±0.16 when assuming fixed slope parameter (G=0.15, G_{12}=0.53) than Bowell's absolute magnitude (Bowell et al., 1989). We also derived slope parameters of asteroids of known spectral types and showed a good agreement with the previous studies within the derived uncertainties. However, our systematic errors on G and G_{12} are significantly larger than in previous work, which is caused by poor temporal and phase coverage of vast majority of the detected asteroids. This disadvantage will vanish when full survey data will be available and ongoing extended and enhanced mission will provide new data.