for the high density of the Earth as a whole without geologists having to suppose that there is a large nickeliron core at the center of the planet. The Earth might be all rock instead.Again, there are "hot spots" in the mantle of the Earth. A hot spot will stay in the same place while the plates of Earth's crust move slowly along above them. Every once in a while, the hot spot gives rise to a ...
되었다. 빛이 유리 섬유 형태의 유도관을 따라 진행하기 위하여는 빛이 진행하는 중심(core) 부분은 굴절률이 높고 외곽(cladding)부분은 낮은 재질로 구성되어야 한다. 그래야 일단 유도관에 진입된 빛이 바깥쪽으로 새어나가지 않게 되는 것이다.실제 광섬유의 단면을 보면 적어도 2개의 다른 재질로 ...
outer layers of Earth, it is almost entirely rocky and includes very little dense iron like that found at the Earth's core. That is why the moon is less dense than Earth.It took a few hundred million years for the moon to cool down sufficiently to have a solid crust, but about 4 billion years ago that solid crust was there, and the oldest rocks that have been brought back date from that ...
있다. 그에 따르면 천왕성의 두터운 대기 아랫쪽에는 정상적인 회전운동을 하고 있는 핵(core)이 존재하며, 따라서 핵의 적도면과 공전궤도면은 같은 방향이라는 것. 즉 핵의 자전과 핵을 둘러싸고 있는 두터운 대기층의 자전이 서로 방향을 달리하기 때문에 해왕성의 자전축(여기에서는 대기의 ...
sooner.The Earth's rotation, however, isn't per-fect. There are shiftings of mass in the Earth. The liquid central core sloshes a bit as the Earth turns. There are earthquakes that re-distribute masses here and there. During winter, masses of water are withdrawn from the ocean and deposited on land as snow, than in the spring the water us returned. There are water currents in the ocean and ...
must end eventually. In five or six billion years more, the sun's hydrogen will be running low and its helium core will have become crucially large and hot. It will reach a point where the helium atoms will start fusing to still more complex atoms. There will be a sudden flow of additional heat and the sun will begin to expand. It will grow much larger and the outermost layers will become ...
from the impact point. Iridium is rare in the Earth's crust, for most of it has settled down in the Earth's central core. It exists in considerably higher concentrations in meteorites, so the presence of higher than usual traces in the crust is considered a relic of a mateoric impact. Comets, however, do not contain any iridium to speak of. The new Soviet finding, therefore, seems to indicate ...
growing for 4,900 years. It was actually alive before the Egyptian Pharaohs built the pyramids. Making use of such cores and of the stumps of deed bristle-cone pines that have not yet rotted away, the tree-ring calendar was eventually stretched back 8,000 years. Obviously, such patterns can be used to study climate cycles and may yield interesting data on just how the weather repeats itself ...
주성분으로 하는 암석)을 여러가지 온도와 압력으로 녹여보았다. 감람암은 지각과 코아(Core·지구중심부의핵)의 사이에 있는 두께 약 3천km 의 맨틀상층부를 형성하는 물질로 때때로 화산분화등으로 지표에 나오는 수도 있다.이것을 비교적 낮은 압력 아래서 녹이면 현무암의 용암을 닮은것이 된다 ...
빛이 전파된다.실제로 광섬유는 원형으로 되어 있으며 중심의 굴절률이 큰 부분을 '코어'(core)라 하고 코어를 둘러싸고 있는 굴절률이 작은 매질을 '클래드'(clad)라 한다. 또한 실용화 되고 있는 광섬유는 코어 부분의 굴절률 분포가 클래드에 비해서 계단형인가 언덕형인가에 따라 스템인덱스(stepindex ...