Sidereal time // is a time-keeping system astronomers use to keep track of the direction to point their telescopes to view a given star in the night sky. Briefly, sidereal time is a "time scale that is based on the Earth's rate of rotation measured relative to the fixed stars."
From a given observation point, a star found at one location in the sky will be found at nearly the same location on another night at the same sidereal time. This is similar to how the time kept by a sundial can be used to find the location of the Sun. Just as the Sun and Moon appear to rise in the east and set in the west due to the rotation of the Earth, so do the stars. Both solar time and sidereal time make use of the regularity of the Earth's rotation about its polar axis, solar time following the Sun while sidereal time roughly follows the stars. More exactly, sidereal time is measured from the vernal equinox (first moment of spring), which is not fixed because the Earth's orbit is not perfectly symmetrical; precession and nutation shift the equinox slightly from one day to the next, so sidereal time is not an exact measure of the rotation of the Earth relative to inertial space. Common time on a typical clock measures a slightly longer cycle, accounting not only for the Earth's axial rotation but also for the Earth's annual revolution around the Sun of slightly less than 1 degree per day (in fact to the nearest arc-second, it takes 365.2422 days to revolve therefore 360 degrees/365.2422 days = 0.9856 degrees or 59 arc-minutes, 8 arc-seconds per day, i.e., slightly less than 1 degree per day).
The Lagrangian points (//; 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 part of a constant-shape pattern with 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 orbit with them.
Lagrangian points are the constant-pattern solutions of the restricted three-body problem. For example, given two massive bodies in orbits around their common center of mass, there are five positions in space where a third body, of comparatively negligible mass, could be placed so as to maintain its position relative to the two massive bodies. As seen in a rotating reference frame matching the angular velocity of the two co-orbiting bodies, the gravitational fields of two massive bodies combined with the satellite's acceleration are in balance at the Lagrangian points, allowing the third body to be relatively stationary with respect to the first two bodies.
In journalism, a human interest story is a feature story that discusses a person or people in an emotional way. It presents people and their problems, concerns, or achievements in a way that brings about interest, sympathy or motivation in the reader or viewer.
Human interest stories may be "the story behind the story" about an event, organization, or otherwise faceless historical happening, such as about the life of an individual soldier during wartime, an interview with a survivor of a natural disaster, a random act of kindness or profile of someone known for a career achievement.
Algeria · Nigeria · Sudan · Ethiopia · Seychelles
Uganda · Zambia · Kenya · South Africa
Afghanistan · Pakistan · India
Nepal · Sri Lanka · Vietnam
China · Hong Kong · Macau · Taiwan
North Korea · South Korea · Japan
Malaysia · Singapore · Philippines · Thailand
Entertainment is a form of activity that holds the attention and interest of an audience, or gives pleasure and delight. It can be an idea or a task, but is more likely to be one of the activities or events that have developed over thousands of years specifically for the purpose of keeping an audience's attention. Although people's attention is held by different things, because individuals have different preferences in entertainment, most forms are recognisable and familiar. Storytelling, music, drama, dance, and different kinds of performance exist in all cultures, were supported in royal courts, developed into sophisticated forms and over time became available to all citizens. The process has been accelerated in modern times by an entertainment industry which records and sells entertainment products. Entertainment evolves and can be adapted to suit any scale, ranging from an individual who chooses a private entertainment from a now enormous array of pre-recorded products; to a banquet adapted for two; to any size or type of party, with appropriate music and dance; to performances intended for thousands; and even for a global audience.
The experience of being entertained has come to be strongly associated with amusement, so that one common understanding of the idea is fun and laughter, although many entertainments have a serious purpose. This may be the case in the various forms of ceremony, celebration, religious festival, or satire for example. Hence, there is the possibility that what appears as entertainment may also be a means of achieving insight or intellectual growth.