Đang chuẩn bị liên kết để tải về tài liệu:
EARTH SCIENCES - Notable Research and Discoveries Part 4

Tham khảo tài liệu 'earth sciences - notable research and discoveries part 4', khoa học tự nhiên, địa lý phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | 52 EARTH SCIENCES To answer the questions about planetary cores and magnetism probes with seismometers must land on the surface. These probes would not only address issues concerning magnetism but also reveal a great deal of information of general interest to geologists. Writing about Mars in a 2005 issue of Science the researchers Yingwei Fei and Constance Bertka of the Carnegie Institution of Washington commented Space missions with multiple landers equipped with seismometers are required to precisely determine the size of the core. Such missions would also provide fundamental information on the structure and density profile of the martian interior which is critical for understanding both the formation and evolution of Mars. This understanding is essential for providing a general context to explore the formation and evolution of terrestrial planets including our own. The same may be said for missions to other planets. But space missions are expensive and must compete for funds with other important projects so these questions have not yet been addressed. Other bodies of the solar system such as Jupiter and the Sun have strong magnetic fields. But Jupiter and the Sun are much larger than the inner planets of the solar system and have vastly different internal structures. Jupiter is mostly hydrogen possibly with a small rocky or metallic core. The Sun is a sphere of hot gas with a volume that would contain about 1 300 000 planets the size of Earth. Some of these gases consist of ions and their movements generate the Sun s enormous and complex magnetic field. Jupiter s magnetic field probably has a similar origin. VARIATIONS IN EARTH S MAGNETIC FIELD The Sun s gaseous structure permits a lot of fluctuations. For instance disturbances such as the one in 1859 described in the sidebar on page 45 transiently altered its properties and the magnetic field of the Sun is also extremely variable. Earth is rocky and much less fluid but the magnetic field of Earth is also .