proper motion - Article Index

Encyclopedia - Luyten 726-8: Encyclopedia - Luyten 726-8
Luyten 726-8 is a binary star system that is one of Earth's nearest neighbors. One of its components is the well-known flare star UV Ceti...   » Read the article

Encyclopedia - Castor Star: Encyclopedia - Castor Star
Castor (α Gem / α Geminorum / Alpha Geminorum) is the second brightest star in the constellation Gemini and one of the brightest stars ...   » Read the article

Encyclopedia - Aries: Encyclopedia - Aries
Aries (Latin for Ram, symbol , Unicode ♈) is one of the constellations of the zodiac. It lies between Pisces to the west and Taurus to ...   » Read the article

Encyclopedia - 61 Cygni: Encyclopedia - 61 Cygni
61 Cygni is a star in the constellation Cygnus. Though it is among the least conspicuous of stars visible in the night sky to an observer...   » Read the article

Encyclopedia - Binary Star: Encyclopedia - Binary Star
A binary star system consists of two stars both orbiting around their barycenter. For each star, the other is its "companion star". The t...   » Read the article

Encyclopedia - Alpha Centauri: Encyclopedia - Alpha Centauri
Alpha Centauri (α Cen / α Centauri) is the brightest star system (a triple star system) in the southern constellation of Centaurus, and...   » Read the article

Encyclopedia - Van Maanen's Star: Encyclopedia - Van Maanen's Star
Van Maanen's Star is a white dwarf, the second such star discovered and the third closest one to the Sun after Sirius B and Procyon B. It...   » Read the article

Encyclopedia - Ayanamsha: Encyclopedia - Ayanamsha
Ayanamsha is a term used in astrology. It is defined as the angle by which the sidereal ecliptic longitude of a celestial body is lesser ...   » Read the article

Encyclopedia - Star Catalogue: Encyclopedia - Star Catalogue
In astronomy, many stars are referred to simply by catalogue numbers. There are a great many different star catalogues which have been pr...   » Read the article

Encyclopedia - William Herschel: Encyclopedia - William Herschel
Sir Wilhelm Friedrich Herschel, FRS (Hanover, November 15, 1738 – August 25, 1822 Slough, then in Buckinghamshire now in Berkshire) was...   » Read the article

Encyclopedia - Transit Of Venus: Encyclopedia - Transit Of Venus
A transit of Venus across the Sun takes place when the planet Venus passes directly between the Sun and the Earth, obscuring a small port...   » Read the article

Encyclopedia - Cygnus Constellation: Encyclopedia - Cygnus Constellation
For the software company, see Cygnus Solutions. Cygnus (from the Latin word Cygnus, meaning "swan") is a northern constellation. It was o...   » Read the article

Encyclopedia - Epsilon Indi: Encyclopedia Ii - Epsilon Indi - Epsilon Indi In Fiction
Epsilon Indi is held by many Star Trek fans to be the home star system of the Andorian race. The star system also made an appearance in t...   » Read the article

Encyclopedia - Galactic Halo: Encyclopedia Ii - Galactic Halo - Halo Stars
The bulk of the stars in a spiral galaxy are located either close to a single plane (the Galactic plane) in more or less conventional cir...   » Read the article

Encyclopedia - Herbig-haro Object: Encyclopedia Ii - Herbig-haro Object - Discovery And History Of Observations
The first Herbig-Haro object was observed in the late 19th century by Burnham, when he looked at the star T Tauri with the 36-inch refrac...   » Read the article

Encyclopedia - Binary Star: Encyclopedia Ii - Binary Star - Background
The term "binary star" was apparently coined by Sir William Herschel in 1802 to designate "a real double star — the union of two stars ...   » Read the article

Encyclopedia - Open Cluster: Encyclopedia Ii - Open Cluster - Historical Observations
The most prominent open clusters such as the Pleiades have been known and recognised as groups of stars since antiquity. Others were know...   » Read the article

Encyclopedia - Star Designation: Encyclopedia Ii - Star Designation - Proper Names
Most bright naked eye stars have traditional names, most of which derive from Arabic, but a few from Latin. See List of traditional star ...   » Read the article

Encyclopedia - Star Catalogue: Encyclopedia Ii - Star Catalogue - Full-sky Catalogues
Bayer and Flamsteed covered only a few thousand stars between them. In theory, full-sky catalogues try to list every star in the sky. The...   » Read the article

Encyclopedia - Astrometric Binary: Encyclopedia Ii - Astrometric Binary - Mathematical Formulation
Even though the companion is invisible, the characteristics of the system can be determined from the observations using Kepler's laws. Th...   » Read the article

Encyclopedia - Observational Astronomy: Encyclopedia Ii - Observational Astronomy - Observation Tools
The key instrument of nearly all modern observational astronomy is the telescope. This serves the dual purposes of gathering more light s...   » Read the article

Encyclopedia - Star Catalogue: Encyclopedia Ii - Star Catalogue - Full-sky Catalogues
Bayer and Flamsteed covered only a few thousand stars between them. In theory, full-sky catalogues try to list every star in the sky. The...   » Read the article

Encyclopedia - Extrasolar Planet: Encyclopedia Ii - Extrasolar Planet - Methods Of Detection
There are currently six methods of detecting extrasolar planets which are too faint relative to their much brighter host stars to be dire...   » Read the article

Encyclopedia - Triangulum Galaxy: Encyclopedia Ii - Triangulum Galaxy - General Information
The Triangulum Galaxy was probably discovered by Giovanni Batista Hodierna before 1654, who may have grouped it together with open cluste...   » Read the article

Encyclopedia - Aries: Encyclopedia Ii - Aries - Mythology
When including fainter stars, visible to the naked eye, the area resembles the head of a ram, having a general herbivore head shape and a...   » Read the article

Encyclopedia - Rotation-powered Pulsar: Encyclopedia Ii - Rotation-powered Pulsar - History
The first known pulsar was discovered by Jocelyn Bell and Antony Hewish in 1967 while they were using a radio array to study the scintill...   » Read the article

Encyclopedia - Alpha Centauri: Encyclopedia Ii - Alpha Centauri - Sky Appearance From Alpha Centauri
Viewed from near Alpha Centauri, the sky (other than the Alpha Centauri stars) would appear very much as it does to observers on Earth, w...   » Read the article

Encyclopedia - 61 Cygni: Encyclopedia Ii - 61 Cygni - General Information
61 Cygni's proper motion is so great, relatively speaking, that its apparent position shifts by an amount equal to the width of the full ...   » Read the article

Encyclopedia - Transit Of Venus: Encyclopedia Ii - Transit Of Venus - Scientific Interest In Transits
Apart from its rarity, the original scientific interest in observing a transit of Venus was that it could be used to determine the size o...   » Read the article

Encyclopedia - Transit Of Venus: Encyclopedia Ii - Transit Of Venus - Scientific Interest In Transits
Apart from its rarity, the original scientific interest in observing a transit of Venus was that it could be used to determine the size o...   » Read the article

Encyclopedia - William Herschel: Encyclopedia Ii - William Herschel - Biography
As Friedrich Wilhelm Herschel in Hanover, Germany, one of ten children (of which four died very young). In 1755 the Hanoverian Guards reg...   » Read the article

Encyclopedia - Binary Star: Encyclopedia Ii - Binary Star - Research Findings
During the past 200 years a large amount of research has been carried out on binary stars leading to some general conclusions. It is beli...   » Read the article

Encyclopedia - Binary Star: Encyclopedia Ii - Binary Star - Research Findings
During the past 200 years a large amount of research has been carried out on binary stars leading to some general conclusions. It is beli...   » Read the article

Encyclopedia - Star Catalogue: Encyclopedia Ii - Star Catalogue - Full-sky Catalogues
Bayer and Flamsteed covered only a few thousand stars between them. In theory, full-sky catalogues try to list every star in the sky. The...   » Read the article

Encyclopedia - Declination: Encyclopedia Ii - Declination - Varying Declination
The declination of all celestial objects vary over time, in different periods. Declination - Sun. The declination of the sun (Sun Dec) ...   » Read the article

Encyclopedia - Edmond Halley: Encyclopedia Ii - Edmond Halley - Biography And Career
Halley was born at Haggerston, London, the son of a wealthy soapboiler. He studied at St Paul's School, and then from 1673 at The Queen's...   » Read the article

Encyclopedia - Cygnus Constellation: Encyclopedia Ii - Cygnus Constellation - Notable Features
Cygnus contains several bright stars. Deneb, α Cygni, is an extremely brilliant star, very prominent despite its distance (1 800 light y...   » Read the article

Encyclopedia - Binary Star: Encyclopedia Ii - Binary Star - Binary Star Classifications
At present, binary stars are classified into four types according to their observable properties: visual binaries spectroscopic binaries...   » Read the article

Encyclopedia - Alpha Centauri: Encyclopedia Ii - Alpha Centauri - Names
It bears the proper name Rigil Kentaurus (often shortened to Rigil Kent), derived from the Arabic phrase Al Rijl al Kentaurus, meaning "f...   » Read the article

Encyclopedia - Extrasolar Planet: Encyclopedia Ii - Extrasolar Planet - Notable Extrasolar Planets
See the list of stars with confirmed extrasolar planets for a list of confirmed observations. Extrasolar planet - Table of extremes. N...   » Read the article

Encyclopedia - Rotation-powered Pulsar: Encyclopedia Ii - Rotation-powered Pulsar - Theory
There is general agreement that what we observe as a pulse is what happens when a beam of radiation points in our direction, once for eve...   » Read the article

Encyclopedia - Binary Star: Encyclopedia Ii - Binary Star - Binary Star Classifications
At present, binary stars are classified into four types according to their observable properties: visual binaries spectroscopic binaries...   » Read the article

Encyclopedia - Transit Of Venus: Encyclopedia Ii - Transit Of Venus - Conjunctions Of Venus With The Sun
Normally when the Earth and Venus are in conjunction they are not aligned with the Sun. Venus' orbit is inclined by 3.4° to the Earth's ...   » Read the article

Encyclopedia - Transit Of Venus: Encyclopedia Ii - Transit Of Venus - Grazing Transits Of Venus
Sometimes Venus only grazes the Sun during a transit. In this case it is possible that in some areas of the Earth a full transit can be s...   » Read the article

Encyclopedia - Transit Of Venus: Encyclopedia Ii - Transit Of Venus - Cultural Meaning
In many cultures of the world, the transit of Venus across the Sun has been regarded as a rare and therefore an important event that mark...   » Read the article

Encyclopedia - Transit Of Venus: Encyclopedia Ii - Transit Of Venus - Simultaneous Transits
The simultaneous occurrence of a transit of Mercury and a transit of Venus is possible, but only in the distant future. Such an event wil...   » Read the article

Encyclopedia - Herbig-haro Object: Encyclopedia Ii - Herbig-haro Object - Proper Motions And Variability
Spectroscopic observations of HH objects show that they are moving away from the source stars at speeds of 100 to 1000 km/s. In rece...   » Read the article

Encyclopedia - Herbig-haro Object: Encyclopedia Ii - Herbig-haro Object - Numbers And Distribution
Over 400 individual HH objects or groups are now known. They are ubiquitous in star-forming H II regions, and are often found in large gr...   » Read the article

Encyclopedia - Binary Star: Encyclopedia Ii - Binary Star - Binary Star Classifications
At present, binary stars are classified into four types according to their observable properties: visual binaries spectroscopic binaries...   » Read the article

Encyclopedia - Alpha Centauri: Encyclopedia Ii - Alpha Centauri - Possibility Of Planet Formation
Computer models of planetary formation suggest that terrestrial planets would be able to form close to both Alpha Centauri A and B, but t...   » Read the article

Encyclopedia - Binary Star: Encyclopedia Ii - Binary Star - Research Findings
During the past 200 years a large amount of research has been carried out on binary stars leading to some general conclusions. It is beli...   » Read the article

Encyclopedia - Cygnus Constellation: Encyclopedia Ii - Cygnus Constellation - History And Mythology
The constellation bears a resemblance to a wide winged, long necked bird, in graceful flight [1]. In Greek mythology, the constellation r...   » Read the article

Encyclopedia - Herbig-haro Object: Encyclopedia Ii - Herbig-haro Object - Physical Characteristics
Emission from HH objects is caused by shock waves when they collide with the interstellar medium, but their motions are complicated. Spec...   » Read the article

Encyclopedia - Alpha Centauri: Encyclopedia Ii - Alpha Centauri - System Components
Alpha Centauri is a triple star system. It consists of two main stars, Alpha Centauri A and Alpha Centauri B (which form a binary star to...   » Read the article

Encyclopedia - Open Cluster: Encyclopedia Ii - Open Cluster - Numbers And Distribution
There are over 1,000 known open clusters in our galaxy, but the true total may be up to ten times higher than that [8]. In spiral ga...   » Read the article

Encyclopedia - Cygnus Constellation: Encyclopedia Ii - Cygnus Constellation - History And Mythology
The constellation bears a resemblence to a wide winged, long necked bird, in graceful flight [1]. In Greek mythology, the constellation r...   » Read the article

Encyclopedia - Alpha Centauri: Encyclopedia Ii - Alpha Centauri - Alpha Centauri In Fiction
Because of its status as our star's nearest galactic neighbor, Alpha Centauri has frequently been referred to in science fiction stories ...   » Read the article

Encyclopedia - Aries: Encyclopedia Ii - Aries - Notable Features
Aries' stars are rather faint except for α Ari (Hamal) and β Ari (Sharatan). Other important stars are γ Ari (Mesarthim) and δ Ari (B...   » Read the article

Encyclopedia - Star Catalogue: Encyclopedia Ii - Star Catalogue - Historical Catalogues
The world's first star catalogue was made by Gan De, a Chinese astronomer in 4th century BC. Although no longer in serious use, mention s...   » Read the article

Encyclopedia - Extrasolar Planet: Encyclopedia Ii - Extrasolar Planet - History Of Detection
Discoveries regarding extrasolar planets were first published in 1989, [1] [2] when variations in the radial velocities of HD 114762 and ...   » Read the article

Encyclopedia - Alpha Centauri: Encyclopedia Ii - Alpha Centauri - System Components
Alpha Centauri is a triple star system. It consists of two main stars, Alpha Centauri A and Alpha Centauri B (which form a binary star to...   » Read the article

Encyclopedia - Alpha Centauri: Encyclopedia Ii - Alpha Centauri - Names
It bears the proper name Rigil Kentaurus (often shortened to Rigil Kent), derived from the Arabic phrase Al Rijl al Kentaurus, meaning "f...   » Read the article

Encyclopedia - Transit Of Venus: Encyclopedia Ii - Transit Of Venus - Grazing Transits Of Venus
Sometimes Venus only grazes the Sun during a transit. In this case it is possible that in some areas of the Earth a full transit can be s...   » Read the article

Encyclopedia - Transit Of Venus: Encyclopedia Ii - Transit Of Venus - Conjunctions Of Venus With The Sun
Normally when the Earth and Venus are in conjunction they are not aligned with the Sun. Venus' orbit is inclined by 3.4° to the Earth's ...   » Read the article

Encyclopedia - Transit Of Venus: Encyclopedia Ii - Transit Of Venus - Simultaneous Transits
The simultaneous occurrence of a transit of Mercury and a transit of Venus is possible, but only in the distant future. Such an event wil...   » Read the article

Encyclopedia - Transit Of Venus: Encyclopedia Ii - Transit Of Venus - Cultural Meaning
In many cultures of the world, the transit of Venus across the Sun has been regarded as a rare and therefore an important event that mark...   » Read the article

Encyclopedia - 61 Cygni: Encyclopedia Ii - 61 Cygni - The Binary System
Although it appears to be a single star to the naked eye, 61 Cygni is in fact a widely separated binary system, composed of two K class (...   » Read the article

Encyclopedia - Extrasolar Planet: Encyclopedia Ii - Extrasolar Planet - Solar System Formation Processes
One question raised by the detection of extrasolar planets is why so many of the detected planets are gas giants which, in comparison to ...   » Read the article

Encyclopedia - Extrasolar Planet: Encyclopedia Ii - Extrasolar Planet - Notable Extrasolar Planets
See the list of stars with confirmed extrasolar planets for a list of confirmed observations. Extrasolar planet - Table of extremes. N...   » Read the article

Encyclopedia - Open Cluster: Encyclopedia Ii - Open Cluster - Morphology And Classification
Open clusters range from very sparse clusters with only a few members to large agglomerations containing thousands of stars. They usually...   » Read the article

Encyclopedia - Open Cluster: Encyclopedia Ii - Open Cluster - Formation
All stars are originally formed in multiple systems, because only a cloud of gas containing many times the mass of the Sun will be heavy ...   » Read the article

Encyclopedia - Open Cluster: Encyclopedia Ii - Open Cluster - Stellar Composition
Because open clusters tend to be dispersed before most of their stars reach the end of their lives, the light from them tends to be domin...   » Read the article

Encyclopedia - Open Cluster: Encyclopedia Ii - Open Cluster - Eventual Fate
Many open clusters are inherently unstable, with a small enough mass that the escape velocity of the system is lower than the average vel...   » Read the article

Encyclopedia - Open Cluster: Encyclopedia Ii - Open Cluster - Studying Stellar Evolution
When a Hertzsprung-Russell diagram is plotted for an open cluster, most stars lie on the main sequence. The most massive stars have begun...   » Read the article

Encyclopedia - Observational Astronomy: Encyclopedia Ii - Observational Astronomy - Observing
A variety of data can be observed for each star. The position coordinates locate the star on the sky using the techniques of spherical as...   » Read the article

Encyclopedia - Observational Astronomy: Encyclopedia Ii - Observational Astronomy - Other Instruments
In addition to examination of the universe in the optical spectrum, astronomers have increasingly been able to acquire information in oth...   » Read the article

Encyclopedia - Triangulum Galaxy: Encyclopedia Ii - Triangulum Galaxy - References In Fiction
In the fictional Star Trek universe, the Triangulum Galaxy is where the USS Enterprise is warped to after a being known as The Traveler u...   » Read the article

Encyclopedia - Galactic Halo: Encyclopedia Ii - Galactic Halo - Halo Dark Matter
Beyond the visible, inner portion of the galactic halo lies a much larger region, known as the dark halo, extended halo or galactic coron...   » Read the article

Encyclopedia - Observational Astronomy: Encyclopedia Ii - Observational Astronomy - Unaided Eye
Prior to the discovery of the telescope, early observational astronomy relied upon the unaided eye and various instruments for measuring ...   » Read the article

Encyclopedia - Observational Astronomy: Encyclopedia Ii - Observational Astronomy - Telescopes
Galileo Galilei was the first person to known to turn a telescope to the heavens and to record what he saw. Since that time, observationa...   » Read the article

Encyclopedia - Observational Astronomy: Encyclopedia Ii - Observational Astronomy - Optical Telescopes
For much of the history of observational astronomy, almost all observation has been performed in the visual spectrum with optical telesco...   » Read the article

Encyclopedia - William Herschel: Encyclopedia Ii - William Herschel - Other Astronomical Work
In his later career, Herschel discovered two satellites of Saturn, Mimas and Enceladus; as well as two satellites of Uranus, Titania and ...   » Read the article