In addition, there are many other weak flows. Observations of these remarkable events have shown that the way the individual stars of a stream crossed a certain point of the sky, called the point of radiation, or simply radiant: the flow or proceeds from that point or whether it found the extended backward direction of falling stars. These points do not change their position, not only for one night, but even for many years. Explain these phenomena can only be as follows: meteors are visible continuously in the same night, belong to the stream, which consists of a large number of small bodies, all of them revolve around the sun in the same general path that crosses Earth's orbit at the point where sometimes Earth Day appearance in the stream, she breaks the last one, and part of small celestial bodies, under the influence of gravity, falling onto its surface. As mentioned above, the Perseids (9 - 13 August) and the Leonids (13 - 14 November), among all the stellar flux reaching the earth, are the strongest. However, not every year that they are the same; Perseids appear at the maximum of once every 108 years and keep it unchanged for 20 - 30 years. Even more startling change in the strength of Leonids. The above description was made of the case, which was observed near Humboldt Kumano. After that, the night of 12 on November 13, 1833 Olmsted and Palmer was observed in S. America, about Nyugevena fireballs, which, like the missiles flew from one point of the sky, there were so many that they fell to the ground like snow flakes and all the sky was on fire; phenomenon lasted 9 hours, on a rough calculation at this time fell more than a quarter of a million stars.
Friday, July 1, 2011
Weight of the Earth
A measure of the proportion of all solids and liquids is a cube. cm chemically pure water, weighing, as we know, 1 oz. By adopting the density of water per unit, and knowing how many times heavier than its substance, we find its specific gravity. 1 cu. cm lime weighs 2.9 grams.: it 2,9 times heavier than 1 cu. cm of water, so they say, that the proportion of lime is 2,9; 1 cu. cm gold weighs 19.4 grams.: its share of 19.4. By challenging experiments were able to determine the proportion of the Earth: it is taken 5.5, which means that the globe in 51 / 2 times heavier than the chemically pure water of the same volume. But among the rocks forming the crust, no one has such a large proportion. If, on the other hand, we define the share of major rock, taking an important part in the composition of the Earth, it would appear that they are harder than the deeper lying: for example, the proportion of sedimentary rocks on average 2.6 and granite - 2 , 7, basalt is 3, and olivine rocks 3,3 - 3,5. We can conclude that inside the Earth below the olivine field are the masses of higher specific gravity, thanks to them, the density of Earth, reaching 5.5 in general. So have a specific gravity of only heavy metals, and because nearly all geologists believe that Earth's core and consists of them, because these metals are amongst the most common is iron, it is highly likely that the metal takes important part in forming the interior of the Earth . Rarity of native iron in the Earth's surface is explained on the one hand, the fact that the eruption of large depths rarely reach the surface, on the other hand, iron is poorly stored in humid air and easily oxidized.
SHAPE AND SIZE OF THE EARTH. MEASURING degree
Reasonably can be argued that in both cases, the data of the Alexandrian scholar were simply translated into modern measures. The new era in the history of the issue begins work Dutchman Snell, who in 1615 first made the trigonometric definition terrestrial arc between Bergen and Alkmarom in the Netherlands and applied for this method having wide circulation in the present. The essence of it are as follows: measured arbitrarily taken the main line, and if the ends of her sighting some distant point, we get a triangle in which the known side and two angles, according to these data it is easy to calculate unknown sides and thus obtain three lines of known value, and if from the last sighting again some new points, and calculating the obtained triangles, repeating the same manipulation, we can cover the whole area a network of triangles and determine, finally, the distance between those points that have been selected to measure the degree. To check the calculations can be directly measured one of the sides of triangles. This technique is very simple in theory but its application meets a number of difficulties, irregular shape of the earth's surface, the effect of temperature on the measuring devices and a host of other conditions interfere with the accuracy of measurements, all these sources of error must be provided and corrected. In measurements of degrees produced in Spain, the base was equal to 14x / 2 miles, the error is not reached, and 3 mm, hence it is clear that the degree of measurement in the modern requirements of science are among the most difficult problems of natural science, which can be performed only for large vehicles.