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Topic Review
EUV-induced Plasma
Science related to effects in the Extreme Ultraviolet (EUV) spectrum range experienced an explosive boom of publications in the last decades. A new application of EUV in lithography was the reason for such a growth. Naturally, an intensive development in such area produces a snowball effect of relatively uncharted phenomena. EUV-induced plasma is one of those. While being produced in the volume of a rarefied gas, it has a direct impact onto optical surfaces and construction materials of lithography machines, and thus has not only scientific peculiarity, but it is also of major interest for the technological application.
  • 1.2K
  • 09 Oct 2020
Topic Review
Europa Thermal Emission Imaging System
The Europa Thermal Emission Imaging System (E-THEMIS) instrument is designed to scan the surface of Europa and identify areas of geologically recent resurfacing through the detection of subtle thermal anomalies. This 'heat detector' will provide high spatial resolution, multi-spectral thermal imaging of Europa to help detect active sites such as outflows and plumes. E-THEMIS will be launched on board the planned Europa Clipper astrobiology mission to Jupiter's moon Europa in 2025. The E-THEMIS uses technology inherited from the THEMIS camera flown on board the 2001 Mars Odyssey orbiter, and the OSIRIS-REx OTES instruments.
  • 379
  • 18 Oct 2022
Biography
Eugen Goldstein
Eugen Goldstein (5 September 1850 – 25 December 1930) was a German physicist. He was an early investigator of discharge tubes, the discoverer of anode rays or canal rays, later identified as positive ions in the gas phase including the hydrogen ion or proton.[1] He was the great uncle of the violinists Mikhail Goldstein and Boris Goldstein. Goldstein was born in 1850 at Gleiwitz Upper Siles
  • 4.2K
  • 30 Dec 2022
Topic Review
Eridanus
Eridanus, the constellation named after the ancient Greek river god, is a sprawling celestial feature stretching across the southern sky. It is the sixth largest of the 88 modern constellations, rich in diverse astronomical treasures.
  • 230
  • 15 Mar 2024
Biography
Erich Kretschmann
Erich Justus Kretschmann (14 July 1887 – 1973) was a Germany physicist.[1] Kretschmann was born in Berlin. He obtained his PhD at Berlin University in 1914 with his dissertation entitled "Eine Theorie der Schwerkraft im Rahmen der ursprünglichen Einsteinschen Relativitätstheorie"[2] (A theory of gravity in the framework of the original Einstein theory of relativity). His advisors were Max
  • 455
  • 08 Dec 2022
Topic Review
Ergontropic Dynamics
Ergontropic dynamics is a concept that links dynamics and thermodynamics based on the concept of energy, work, and entropy. It differs from standard treatments, in particular, in that it does not derive irreversible thermodynamics from reversible microscopic dynamics and the force term, dp/dt, is derived from these principles and not assumed ab initio. The concept offers an intelligible explanation of a number of physical problems by embedding the universal tendency of energy to a minimum and entropy to a maximum in a new framework. The result is a modification of Newton’s dynamic equation of motion that bases the principles of mechanics on the concepts of energy and entropy, rather than the usual definition of force, and integrates the description of translation and vortex motion into a consistent framework. By reframing the fundamental concepts of classical mechanics and electrodynamics through the perspectives of energy and entropy, ergontropic dynamics stands as a novel framework that transcends both of these fields. 
  • 499
  • 30 Aug 2023
Topic Review
Equuleus
Equuleus, Latin for "the little horse," is one of the 88 modern constellations recognized by the International Astronomical Union. Despite its small size and dim stars, Equuleus holds historical significance, dating back to ancient times when it was known as a separate constellation or asterism. Today, it remains a subtle yet intriguing feature of the night sky, nestled between the larger constellations of Pegasus and Delphinus.
  • 125
  • 15 Mar 2024
Topic Review
Equinox (Celestial Coordinates)
In astronomy, an equinox is either of two places on the celestial sphere at which the ecliptic intersects the celestial equator. Although there are two intersections of the ecliptic with the celestial equator, by convention, the equinox associated with the Sun's ascending node is used as the origin of celestial coordinate systems and referred to simply as "the equinox". In contrast to the common usage of spring/vernal and autumnal equinoxes, the celestial coordinate system equinox is a direction in space rather than a moment in time. In a cycle of about 25,800 years, the equinox moves westward with respect to the celestial sphere because of perturbing forces; therefore, in order to define a coordinate system, it is necessary to specify the date for which the equinox is chosen. This date should not be confused with the epoch. Astronomical objects show real movements such as orbital and proper motions, and the epoch defines the date for which the position of an object applies. Therefore, a complete specification of the coordinates for an astronomical object requires both the date of the equinox and of the epoch. The currently used standard equinox and epoch is J2000.0, which is January 1, 2000 at 12:00 TT. The prefix "J" indicates that it is a Julian epoch. The previous standard equinox and epoch was B1950.0, with the prefix "B" indicating it was a Besselian epoch. Before 1984 Besselian equinoxes and epochs were used. Since that time Julian equinoxes and epochs have been used.
  • 634
  • 02 Dec 2022
Topic Review
Equatorial Coordinate System
The equatorial coordinate system is a celestial coordinate system widely used to specify the positions of celestial objects. It may be implemented in spherical or rectangular coordinates, both defined by an origin at the centre of Earth, a fundamental plane consisting of the projection of Earth's equator onto the celestial sphere (forming the celestial equator), a primary direction towards the vernal equinox, and a right-handed convention. The origin at the centre of Earth means the coordinates are geocentric, that is, as seen from the centre of Earth as if it were transparent. The fundamental plane and the primary direction mean that the coordinate system, while aligned with Earth's equator and pole, does not rotate with the Earth, but remains relatively fixed against the background stars. A right-handed convention means that coordinates increase northward from and eastward around the fundamental plane.
  • 1.2K
  • 16 Nov 2022
Topic Review
Epoch
In astronomy, an epoch or reference epoch is a moment in time used as a reference point for some time-varying astronomical quantity. It is useful for the celestial coordinates or orbital elements of a celestial body, as they are subject to perturbations and vary with time. These time-varying astronomical quantities might include, for example, the mean longitude or mean anomaly of a body, the node of its orbit relative to a reference plane, the direction of the apogee or aphelion of its orbit, or the size of the major axis of its orbit. The main use of astronomical quantities specified in this way is to calculate other relevant parameters of motion, in order to predict future positions and velocities. The applied tools of the disciplines of celestial mechanics or its subfield orbital mechanics (for predicting orbital paths and positions for bodies in motion under the gravitational effects of other bodies) can be used to generate an ephemeris, a table of values giving the positions and velocities of astronomical objects in the sky at a given time or times. Astronomical quantities can be specified in any of several ways, for example, as a polynomial function of the time-interval, with an epoch as a temporal point of origin (this is a common current way of using an epoch). Alternatively, the time-varying astronomical quantity can be expressed as a constant, equal to the measure that it had at the epoch, leaving its variation over time to be specified in some other way—for example, by a table, as was common during the 17th and 18th centuries. The word epoch was often used in a different way in older astronomical literature, e.g. during the 18th century, in connection with astronomical tables. At that time, it was customary to denote as "epochs", not the standard date and time of origin for time-varying astronomical quantities, but rather the values at that date and time of those time-varying quantities themselves. In accordance with that alternative historical usage, an expression such as 'correcting the epochs' would refer to the adjustment, usually by a small amount, of the values of the tabulated astronomical quantities applicable to a fixed standard date and time of reference (and not, as might be expected from current usage, to a change from one date and time of reference to a different date and time).
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  • 22 Nov 2022
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