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The distance to the Moon can be measured with millimeter precision. [27] The Moon is spiraling away from Earth at a rate of 3.8 cm/year. [24] [42] This rate has been described as anomalously high. [43] The fluid core of the Moon was detected from the effects of core/mantle boundary dissipation. [44]
APOLLO shooting a laser at the Moon. The laser pulse is reflected from the retroreflectors on the Moon (see below) and returned to the telescope. The round-trip time tells the distance to the Moon to great accuracy. In this picture the Moon is very over-exposed, needed to make the laser beam visible. Apollo 15 Lunar Ranging Retro-Reflector (LRRR).
Accommodation is the process by which the vertebrate eye changes optical power to maintain a clear image or focus on an object as its distance varies. In this, distances vary for individuals from the far point—the maximum distance from the eye for which a clear image of an object can be seen, to the near point—the minimum distance for a ...
Myopia, or nearsightedness, is a vision condition where close objects look clear but far objects look blurry. Trouble seeing far away? Why experts say you should take this more seriously.
A diagram of a typical nautical sextant, a tool used in celestial navigation to measure the angle between two objects viewed by means of its optical sight. Celestial navigation, also known as astronavigation, is the practice of position fixing using stars and other celestial bodies that enables a navigator to accurately determine their actual current physical position in space or on the ...
Single vision prescription lenses They can correct only one form of defective vision, either far-sightedness or near-sightedness. Multifocal lenses The multifocal lenses can correct defective vision in multiple focus, for example: near-vision as well as far-vision. This are particularly beneficial for presbyobia. [38]
Orion took the snapshot around its maximum distance from Earth of 268,563 miles. That's the farthest any human-oriented spacecraft has traveled, beating even Apollo 13's record of 248,655 miles ...
If the actual observed altitude Ho is smaller than the computed altitude Hc this means the observer is farther away from the body than the observer at the assumed position, and vice versa. For each minute of arc the distance is one NM and the difference between Hc and Ho expressed in minutes of arc (which equal NM) is termed the "intercept".