Horizon
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HORIZON (Gr. 6piTcov, dividing), the apparent circle around which the sky and earth seem to meet.
Horizon
Related Category: Astronomy: General
in astronomy, roughly circular line bounding an observer's view of the surface of the earth where the sky and earth seem to meet. This is the visible horizon.
Horizontal Branch stars
This is a phase of stellar evolution undergone by intermediate-mass stars, i.e. those with masses 0.8 M⊙ < < 8 M⊙, a range which encompasses the majority of stars in the Galaxy, including our Sun.
Horizontal branch
The horizontal branch (HB) is a stage of stellar evolution which immediately follows the red giant branch in stars whose masses are similar to the Sun's.
horizon
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The horizontal branches of some globular clusters have extended blue tails (at the high-temperature end of the branch) which dip to lower luminosities, whose stars are called extreme horizontal branch stars.
Duffett-Smith, P. "Horizon Coordinates," "Equatorial to Horizon Coordinate Conversion," and "Horizon to Equatorial Coordinate Conversion." §17, 25, and 26 in Cambridge, England: Cambridge University Press, p. 26, 36-37, and 38-39, 1992.
New Horizons Mission to Pluto
New Horizons is a spacecraft goaled to fly past Pluto in the summer of 2015. When it arrives, New Horizons will map the surfaces of Pluto and its biggest moon, Charon.
New Horizons
Mercury to Neptune: the golden age of planetary exploration ...
New Horizons Links
In additon to the Rings Node, the following PDS Nodes have New Horizons web pages.
Atmospheres Node
Small Bodies Node (SBN) ...
New Horizons is on the fastest spacecraft trip ever to the outer Solar System. It reached the orbit of Earth's Moon in fewer than 9 hours, then hustled off toward Jupiter. It will be passing by Jupiter from February 25 and March 2, 2007.
Event Horizon:
Immediately on publication of Einstein's paper on general relativity, the German astronomer Karl Schwarzschild found a mathematical solution to the new field equations, ...
The cosmic particle horizon is related to the age of the Universe. Its size certainly grows, but with the age of the Universe, not with the expansion of the Universe. As the expansion slows, we certainly would see more in the future than in the past.
If you are standing atop a mountain 1 km high, h = 1 km and your horizon should be 112.88 km away (we neglect the refraction of light in the atmosphere, which may modify this value).
Definition: event horizon: The distance from a black hole within which nothing can escape. In addition, nothing can prevent a particle from hitting the singularity in a very short amount of proper time once it has entered the horizon.
horizon: the line of intersection between the sky and the Earth. For normal astronomical purposes, the observer's horizon is taken to be the great circle on the celestial sphere on which every point is 90° from the observer's zenith.
horizon problem One of two conceptual problems with the standard Big Bang model, which is that some regions of the universe which have very similar properties are too far apart to have exchanged information in the age of the universe.
Horizontal asymptotes
Suppose f is a function. Then the line y = a is a horizontal asymptote for f if ...
Horizon problem. Our observable patch of the Universe grows from a much smaller initial patch in the inflationary Universe (right) than it does in the standard Friedmann models (left.).
Horizon Co-ordinates The system of celestial co-ordinates in which the observer's horizon is the reference plane and the north point is the reference direction. The positions are given in altitude and azimuth.
HORIZONTAL BRANCH - Region of the Hertzsprung-Russell diagram where post-main sequence stars again reach hydrostatic equilibrium. At this point, the star is burning helium in its core, and hydrogen in a shell surrounding the core.
Horizon -- The line marking the apparent junction of Earth and sky. For the technical definition, please follow this link to the U.S. Naval Observatory's Astronomical Applications.
h -- Hour, 60 minutes of time.
Horizontal Branch
In the H-R diagram of a globular cluster, the sequence of stars extending from the red giants toward the blue side of the diagram; includes RR Lyrae stars.
Horoscope ...
Horizon Problem
(a) A quandary in standard big bang theory, which indicates that few of the particles of the early universe would have had time to be in causal contact with one another at the outset of cosmic expansion.
Horizon. The great circle on the celestial sphere which is everywhere 90 degrees from the observers zenith, the point directly overhead the observer.
Hours, Minutes, Seconds (h, m, s). Measure of time or right ascension.
horizon problem: In cosmology, the circumstance that the primordial background radiation seems much more isotropic than could be explained by the standard big bang theory.
Horizon System - A coordinate system, using altitude and azimuth as coordinates, used to locate the positions of objects in the sky ...
THE HORIZON AND FLATNESS PROBLEMS
In the late 1970s, cosmologists trying to piece together the evolution of the universe were confronted with two nagging problems that had no easy explanation within the standard Big Bang model.
New Horizons Kids Club
New Horizons wasn't the only voyage launched on Janurary 19, 2006. The New Horizons team welcomes five new "Pluto Pals.
The Horizontal Branch
The energy released by the helium flash raises the core temperature to the point where it is no longer degenerate. It thus starts to behave again as an ideal gas so can expand and cool.
The horizon problem
The horizon problem results from the premise that information cannot travel faster than light, and hence two regions of space which are expanding at faster than the speed of light relative to each other cannot communicate.
Event Horizon
The "surface" of a black hole is the so-called event horizon, an imaginary surface surrounding the mass of the black hole.
Event horizon
This is the boundary of the region from which not even light can escape, but at the same time, light does not get sucked into the black hole.
event horizon
the boundary of a black hole from inside which light cannot escape
exit pupil ...
event horizon
The radius that a spherical mass must be compressed to in order to transform it into a black hole, or the radius at which time and space switch responsibilities.
Event horizon- the "edge" of a black hole: and imaginary surface where the escape velocity reaches the speed of light ...
Event Horizon
the invisible boundary around a black hole past which nothing can escape the gravitational pull - not even light.
[edit] Horizontal axis g-force
The human body is better at surviving g-forces that are perpendicular to the spine.
EVENT HORIZON
The event horizon is the radius from a black hole inside of which it is impossible to escape (a "point of no return" called the Schwarzschild radius).
The New Horizons spacecraft was launched in January 2006. It will encounter Jupiter on February 28, 2007, and Pluto in July 2015. Click here21 to see where New Horizons is now.
The term event horizon is also used to describe the Schwarzschild radius, since that is the closest you can see an "event" happening near a black hole.
Horizontal branch stars are characterized by helium core burning and hydrogen burning in a shell surrounding the core.
2. What element makes up the core of a massive star just before it goes supernova?
Iron.
Horizontal contrasts of temperature were measured by Voyager in two broad altitude ranges, one located in the range of 60 to 200 millibars and the other of 500 to 1,000 millibars.
horizontal branch - (n.)
A sequence of stars in the H-R diagram of a globular cluster, extending horizontally across the diagram to the left from the red-giant region.
HORIZONTAL BRANCH
The horizontal branch is a part of the Hertzsprung -Russell (H-R) diagram that represents stars that burn helium in thier cores. These mostly large stars lie along the top of the H-R diagram.
New Horizons
When NASA's New Horizons spacecraft arrives at Pluto in 2015, humanity will have completed its initial reconnaissance of our roughly 4.6-billion-year-old cosmic backyard.
The horizon size at the last-scattering surface, important not only for big questions of causal connectivity but in the growth of perturbations, is 184 (W h²) -1/2 Mpc.
The horizon problem is solved by inflation because regions that appear to be isolated from each other were in contact with each other before the inflation period. They came into equilibrium before inflation expanded them far away from each other.
El horizonte es el plano que define la mitad del cielo que usted puede ver.
Altitud es el ángulo entre el objeto que usted está mirando y su horizonte.
event horizon
The boundary of the region of a black hole from which no radiation may escape. No event that occurs within the event horizon is visible to a distant observer.
evolutionary track ...
Event Horizon
The spherical outer boundary of a black hole. Once matter crosses this threshold, the speed required for it to escape the black hole's gravitational grip is greater than the speed of light.
Excited State ...
EVENT HORIZON
The event horizon is the radius from a inside of which it is impossible to escape (a "point of no return" called the ). It is also the radius at which a mass must be compressed down to in order to turn it into a black hole.
Over Eros' Horizon
This incredible picture of Eros, taken on February 14, 2000, shows the view looking from one end of the asteroid across the gouge on its underside and toward the opposite end.
Azimuth Horizontal co-ordinate of an object's position in the sky. Derived by drawing an imaginary vertical line from the object to the horizon below. The position is then expressed in degrees east from the north point.
radar horizon The angle of elevation at which the beam from a radar antenna is intercepted by the earth's horizon. Compare radio horizon. radar indicator = radarscope. radar mile A time unit of 10.
* Given a true horizon, as at sea, the center of the Sun on the equinox should set twelve hours after it rises -- at least in theory.
1. Use the JPL Horizons Ephemerides program to get the J2000 astrometric coordinates and the apparent coordinates for the time I was planning on observing Himalia.
2. Download the Digitized Sky Survey photograph centered at the apparent coordinates.
The boundary surrounding the region where light, and hence everything else, cannot escape is called the event horizon.
Azimuth is the horizontal direction or bearing of an object in the sky. It sets the line along which the altitude is measured. The azimuth is designated as the angle created by that imaginary line and true north.
Low on the southern horizon lies the crown jewel of spring equatorial skies. There are now six constellations among these stars. They are Puppis the Poop, Vela the Sails, Pyxis the Compass, Carina the Keel, Volans the Flying Fish and Columba the Dove.
 See also: Earth, Light, Time, Sun, Planet
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