... El Sol gobierna el cielo diurno, pero por la noche, especialmente si la Luna no brilla, el espect culo pertenece a las estrellas. ... Para los antiguos observadores parec a como si la Tierra fuera el centro de una " esfera celeste " salpicada de estrellas, lo cual reforzaba la creencia, sostenida durante miles de a os, de que nosotros ramos el centro del Universo. ... Por tanto, cuando interesa, todav a podemos usar la esfera celeste para marcar las posiciones de las estrellas en el cielo. ...

... What Is An Eruption? ... Terrestrial Volcanoes Image and Animation Index . ... Volcanic Eruption on Iceland . ... Oceanic volcanoes fed by "hot spots" in the crust commonly have frequent non-explosive eruptions of slow-moving basaltic lava . ... Eruptions may come along only decades apart, but not always from the same volcano. ... The main volcanic crater on Mount Pinatubo produced by the June 1991 eruptions, and the steep slopes on the upper flanks of the volcano, are easily seen in this image. ...

... Pictures taken by Gemini astronauts almost 30 years ago are much clearer than those taken by space shuttle astronauts today. ... The plateau is 1,200 kilometers (746 miles) from east to west and 900 kilometers (560 miles) north to south, with a mean elevation of about 4900 meters (16,000 feet). ... Courtesy LPI/NASA. ... Oblique view, Galapagos Islands, Pacific Ocean . ... Like Tupai, it probably originated as a fringing reef developed around a volcanic island that has long since disappeared. ...