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Electromagnetic waves

Focus for electromagnetic waves

Gravitational waves, neutrinos

Focus for gravitational waves, neutrinos

Figure 8.2. The Sun bending light acts as a lens.

Gravitational waves, neutrinos

Focus for electromagnetic waves

Focus for gravitational waves, neutrinos

Figure 8.2. The Sun bending light acts as a lens.

Sun radius: when r is equal to the Sun radius, starlight rays focus at the point closest to Earth. This minimum focus is located at a distance about 542 AU (in fact, focus distance depends also on the light wavelength).

Calculations show that the angular and spatial resolution made possible by observing objects through this powerful "lens" are worth noticing. The resolution is a function not only of the gain due to the lensing effect of the Sun, but also of the gain of the antenna on the spacecraft, proportional to its dish radius, rantenna. The total gain is, in fact, the product of the two [Maccone, 2002, p. 12]:

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