The lack of an atmosphere on the Moon permits the cosmic radiation and solar wind plasma to reach the lunar surface unimpeded. Thus, analogous to the advantages of lunar-based observations of electromagnetic radiation, detectors can be placed on the lunar surface to study the origins, character, and directions of cosmic radiation. Similarly, measurements of the solar wind can be made directly from the lunar surface.
The interaction of the Earth's magnetic field with the solar wind creates Earth's "magnetosphere", which is a teardrop-shaped cavity in the solar wind that encloses the Earth. The elongated tail of the magnetosphere extends beyond the orbit of the Moon in the anti-sunward direction so that the Moon enters, interacts with, and exits the magnetosphere once every lunar month. Because of the unique properties of the Moon's orbit about the Earth, the structure and dynamics of Earth's magnetosphere can be studied directly from the lunar surface.
22 Quasars, or quasi-stellar objects, are thought to be primordial galaxies that have very large black holes in their center. Quasars emit far more energy than ordinary galaxies, and their emission spectra have large red shifts, indicating that they are among the earliest structures to form after the "big bang'', and that they lie at the edge of the visible universe.
23 The effort to produce a whole-sky survey of galaxies will be immense: the Hubble "deep-field'' image comprises a region of the northern sky that would be subtended by a small coin placed at 75 feet (25 meters) from the telescope.
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