Professional astronomy is split into observational and theoretical branches. Observational astronomy is focused on acquiring data from observations of astronomical objects. This data is then analyzed using basic principles of physics. Theoretical astronomy is oriented toward the development of computer or analytical models to describe astronomical objects and phenomena. These two fields complement each other. Theoretical astronomy seeks to explain observational results and observations are used to confirm theoretical results.
Astronomy is one of the few sciences in which amateurs play an active role. This is especially true for the discovery and observation of transient events. Amateur astronomers have helped with many important discoveries, such as finding new comets. (Full article...)
Image 3Segment of the astronomical ceiling of Senenmut's Tomb (circa 1479–1458 BCE), depicting constellations, protective deities, and twenty-four segmented wheels for the hours of the day and the months of the year (from History of astronomy)
Image 5Amateur astronomy groups are often involved in outreach in order to introduce astronomy to the general public (from Amateur astronomy)
Image 6An image of the Cat's Paw Nebula created combining the work of professional and amateur astronomers. The image is the combination of the 2.2-metre MPG/ESO telescope of the La Silla Observatory in Chile and a 0.4-meter amateur telescope. (from Amateur astronomy)
Image 7Amateur astronomer recording observations of the sun. (from Amateur astronomy)
Image 9Portrait of the Flemish astronomer Ferdinand Verbiest who became Head of the Mathematical Board and Director of the Observatory of the Chinese emperor in 1669 (from Astronomer)
Image 12Artist conception of the Big Bang cosmological model, the most widely accepted out of all in physical cosmology (neither time nor size to scale) (from Physical cosmology)
Image 16Places like Paranal Observatory offer crystal clear skies for observing astronomical objects with or without instruments. (from Amateur astronomy)
Image 17Comparison of CMB (Cosmic microwave background) results from satellites COBE, WMAP and Planck documenting a progress in 1989–2013 (from History of astronomy)
Image 22ALMA is the world's most powerful telescope for studying the Universe at submillimeter and millimeter wavelengths. (from Observational astronomy)
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Enhanced color image of Io from the Galileo spacecraft, taken in 1999.
Io (/ˈaɪ.oʊ/), or Jupiter I, is the innermost and second-smallest of the four Galilean moons of the planet Jupiter. Slightly larger than Earth's moon, Io is the fourth-largest moon in the Solar System, has the highest density of any moon, the strongest surface gravity of any moon, and the lowest amount of water by atomic ratio of any known astronomical object in the Solar System. It was discovered in 1610 by Galileo Galilei and was named after the mythological character Io, a priestess of Hera who became one of Zeus's lovers.
With over 400 active volcanoes, Io is the most geologically active object in the Solar System. This extreme geologic activity is the result of tidal heating from friction generated within Io's interior as it is pulled between Jupiter and the other Galilean moons—Europa, Ganymede and Callisto. Several volcanoes produce plumes of sulfur and sulfur dioxide that climb as high as 500 km (300 mi) above the surface. Io's surface is also dotted with more than 100 mountains that have been uplifted by extensive compression at the base of Io's silicate crust. Some of these peaks are taller than Mount Everest, the highest point on Earth's surface. Unlike most moons in the outer Solar System, which are mostly composed of water ice, Io is primarily composed of silicate rock surrounding a molten iron or iron sulfide core. Most of Io's surface is composed of extensive plains with a frosty coating of sulfur and sulfur dioxide. (Full article...)
... that the Antlia Dwarf galaxy may have distorted the shape of its neighbour NGC 3109 one billion years ago?
... that AP Columbae, the closest young star known, formed after the dinosaurs became extinct?
... that a planet was discovered around the star MOA-2009-BLG-387L after it eclipsed a background star, refracting the star's light in a process called gravitational microlensing?
... that Jessen's icosahedron has been used for both the "Skwish" children's toy and a NASA proposal for a "super ball bot" to cushion space landers on other planets?
... that Nandivada Rathnasree, who ran Delhi's planetarium, proposed that astronomers could be taught using India's stone-built observatories?
... that in early depictions of Uranus in fiction, the planet was portrayed as solid
... that Michael Collins has been called "one of the best clarinettists walking the planet" by The Times?
IC 405, also Sharpless 229 (Sh2-229), Caldwell 31 and The Flaming Star Nebula, is an emission/reflection nebula and a Caldwell object in the constellation Auriga, surrounding the bluish star AE Aurigae. It shines at magnitude +6.0. The nebula is about 5 light-years across. This is a white light image of the Flaming Star Nebula showing the "smoke" of reflection nebula.