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A stellarium is a three-dimensional map of the stars, typically centered on Earth. They are common fixtures at planetariums, where they illustrate the local deep space out to perhaps 50 light years. Older examples were normally built using small colored balls or lights on support rods (painted black to make them less obvious), but more recent examples use a variety of projection techniques instead.
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The International Phonetic Alphabet (IPA) is an alphabetic system of phonetic notation based primarily on the Latin script. It was devised by the International Phonetic Association in the late 19th century as a standardized representation of speech sounds in written form. The IPA is used by lexicographers, foreign language students and teachers, linguists, speech–language pathologists, singers, actors, constructed language creators, and translators.
In mathematics, a tensor is an algebraic object that describes a multilinear relationship between sets of algebraic objects related to a vector space. Tensors may map between different objects such as vectors, scalars, and even other tensors. There are many types of tensors, including scalars and vectors, dual vectors, multilinear maps between vector spaces, and even some operations such as the dot product. Tensors are defined independent of any basis, although they are often referred to by their components in a basis related to a particular coordinate system; those components form an array, which can be thought of as a high-dimensional matrix.
A prime meridian is an arbitrarily-chosen meridian in a geographic coordinate system at which longitude is defined to be 0°. Together, a prime meridian and its anti-meridian form a great circle. This great circle divides a spheroid, like Earth, into two hemispheres: the Eastern Hemisphere and the Western Hemisphere. For Earth's prime meridian, various conventions have been used or advocated in different regions throughout history. Earth's current international standard prime meridian is the IERS Reference Meridian. It is derived, but differs slightly, from the Greenwich Meridian, the previous standard.
A mathematical symbol is a figure or a combination of figures that is used to represent a mathematical object, an action on mathematical objects, a relation between mathematical objects, or for structuring the other symbols that occur in a formula. As formulas are entirely constituted with symbols of various types, many symbols are needed for expressing all mathematics.
Achernar is the brightest star in the constellation of Eridanus and the ninth-brightest in the night sky. It has the Bayer designation Alpha Eridani, which is Latinized from α Eridani and abbreviated Alpha Eri or α Eri. The name Achernar applies to the primary component of a binary system. The two components are designated Alpha Eridani A and B, with the latter known informally as Achernar B. As determined by the Hipparcos astrometry satellite, this system is located at a distance of approximately 139 light-years from the Sun.
Stellarium is a free and open-source planetarium, licensed under the terms of the GNU General Public License version 2 or any later version, available for Linux, Windows, and macOS. A port of Stellarium called Stellarium Mobile is available for Android, iOS, and Symbian as a paid version, being developed by Noctua Software. These have a limited functionality, lacking some features of the desktop version. All versions use OpenGL to render a realistic projection of the night sky in real time.
The OpenCD project is a discontinued open-source project aimed to introduce users of Microsoft Windows to the benefits of free and open-source software (FOSS). It is a CD image that can freely be downloaded and copied. The OpenCD team screened programs for stability, quality, and ease of installation, and only distributed programs available under an OSI-approved open-source license, which allows users to freely use and distribute the disc as they wish. It was sponsored by Canonical Ltd., for a period.
In amateur astronomy, "GoTo" refers to a type of telescope mount and related software that can automatically point a telescope at astronomical objects that the user selects. Both axes of a GoTo mount are driven by a motor and controlled by a computer. It may be either a microprocessor-based integrated controller or an external personal computer. This differs from the single-axis semi-automated tracking of a traditional clock-drive equatorial mount.
Paksha (Sanskrit: पक्ष, romanized: pakṣa) refers to a fortnight or a lunar phase in a month of the Hindu lunar calendar.
The Gornergrat is a rocky ridge of the Pennine Alps, overlooking the Gorner Glacier south-east of Zermatt in Switzerland. It can be reached from Zermatt by the Gornergrat rack railway (GGB), the highest open-air railway in Europe. Between the Gornergrat railway station and the summit is the Kulm Hotel. In the late 1960s two astronomical observatories were installed in the two towers of the Kulmhotel Gornergrat. The project “Stellarium Gornergrat” is hosted in the Gornergrat South Observatory.
Sky-Map.org is a wiki and interactive sky map that covers over half a billion known celestial bodies. WikiSky is designed, in part, as a wiki. As such users can edit information about different stars by writing articles, adding Internet links, uploading images, or creating a special interest group for a specific task.
The OpenDisc project offered a selection of high quality open source software on a disc for Microsoft Windows users. The aims of the project were "to provide a free alternative to costly software, with equal or often better quality equivalents to proprietary, shareware or freeware software for Microsoft Windows", and "to educate users of Linux as an operating system for home, business and educational use".
Fabien Chéreau is a French research engineer and computer programmer best known for authoring the planetarium software Stellarium, a free, open source astronomy software package which renders 3D photo-realistic skies in real time.
Inuit astronomy is centered around the Qilak, the Inuit name for the celestial sphere and the home for souls of departed people. Inuit beliefs about astronomy are the shaped by the harsh climate in the Arctic and the resulting difficulties of surviving and hunting in the region. The stars were an important tool to track time, seasons, and location, particularly during winter.
Tomar-Re is a character appearing in comics published by DC Comics. He is a member of the Green Lantern Corps, as well as the predecessor and father of Tomar-Tu.
VALO-CD, a distribution of open-source software on a CD for Microsoft Windows, aims to spread knowledge and the use of open-source software.
Emmabuntüs is a Linux distribution derived from Debian and designed to facilitate the restoration of computers donated to humanitarian organizations like the Emmaüs Communities.
ANGLE is an open source, cross-platform graphics engine abstraction layer developed by Google. ANGLE translates OpenGL ES 2/3 calls to DirectX 9, 11, OpenGL or Vulkan API calls. It's a portable version of OpenGL but with limitations of OpenGL ES standard.
Nightshade is a simulation and visualization software for teaching and exploring astronomy, Earth science, and related topics. Its focus is on use in digital planetarium systems or as an educational tool, with additional features to allow it to also be used on desktop or laptop computers. It operates on Linux, macOS and Windows.
The Hindu calendar is based on a geocentric model of the Solar System. A geocentric model describes the Solar System as seen by an observer on the surface of the Earth.