Radio Astronomy

the recording and study of radio waves given out by many bodies in space including the Sun, stars and QUASARS.

Taken from Dictionary of Science

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Radio astronomy is a subfield of astronomy that studies celestial objects at radio frequencies. It differs from radar astronomy in that the latter utilizes artificial, rather than natural, radio sources. The initial detection of radio waves from an astronomical object (the Milky Way) was made in the 1930s, but subsequent advances (especially post-World War II) have identified a number of different sources of radio emission. These include stars and galaxies as well as entirely new classes of objects, such as Radio Galaxies, Pulsars and Masers. The discovery of the Cosmic Microwave Background Radiation was a particularly significant event. Radio astronomy is conducted using large radio antenna referred to as radio telescopes, that are either used singularly, or with multiple linked telescopes utilizing the techniques of radio interferometry and aperture synthesis. The latter has allowed radio sources to be imaged with unprecedented angular resolution.

Taken from Wikipedia

Lagrangian Points

in particular, with respect to the Earth and Moon, the locations where the gravitational forces are equal and so objects positioned at such points remain fixed. There are five such points between the Earth and Moon.

Taken from Dictionary of Science

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The Lagrangian points (pronounced /ləˈgrandʒiən/; also Lagrange points, L-points, or libration points), are the five positions in an orbital configuration where a small object affected only by gravity can theoretically be stationary relative to two larger objects (such as a satellite with respect to the Earth and Moon). The Lagrange points mark positions where the combined gravitational pull of the two large masses provides precisely the centripetal force required to rotate with them. They are analogous to geostationary orbits in that they allow an object to be in a "fixed" position in space rather than an orbit in which its relative position changes continuously.

More technically and precisely, Lagrangian points are the stationary solutions of the circular restricted three-body problem. For example, given two massive bodies in circular orbits around their common center of mass, there are five positions in space where a third body, of comparatively negligible mass, could be placed which would then maintain its position relative to the two massive bodies. As seen in a rotating reference frame with the same period as the two co-orbiting bodies, the gravitational fields of two massive bodies combined with the centrifugal force are in balance at the Lagrangian points, allowing the third body to be stationary with respect to the first two bodies.

Taken from Wikipedia

Nanometre

a unit of measurement that is used for extremely small objects. One nanometre equals one thousand millionth of a metre (i.e., 10^-9.m).

Taken from Dictionary of Science












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A nanometre (American spelling: nanometer; symbol nm) (Greek: νάνος, nanos, "dwarf"; μέτρον, metrοn, "unit of measurement") is a unit of length in the metric system, equal to one billionth of a meter.

It is one of the more often used units for very small lengths, and equals ten Ångström, an internationally recognized non-SI unit of length. It is often associated with the field of nanotechnology and the wavelength of light. Formerly, millimicron (symbol mµ) was used for the nanometre. The symbol µµ has also been used.

It is also the most common unit used to describe the manufacturing technology used in the semiconductor industry. It is the most common unit to describe the wavelength of light, with visible light falling in the region of 400–700 nm.

Taken from Wikipedia