| Piú votate - The Universe Inside |
crater_fog2_1600.jpgIn the Mist109 visite
(19 voti)
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CloudsandClouds.jpgClouds and Clouds108 visiteThe clouds in the foreground are much different than the clouds in the background. In the foreground are a photogenic deck of Earth-based water clouds. The long exposure used to create the above photograph makes the light from the left, reflected from Phoenix, Arizona, USA, appear like a sunset. Far in the distance, however, are star clouds from the disk of our Milky Way Galaxy. Billions of stars like our Sun live there, circling our Galactic center every 200 million years. Contrast between the water clouds and the star clouds has been digitally enhanced. Between the two, visible on the upper right, is the planet Jupiter.
(19 voti)
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CollidingGalaxies-PIA02180_modest.jpgHearts of Glass119 visiteThis artist's concept shows delicate greenish crystals sprinkled throughout the violent core of a pair of colliding galaxies. The white spots represent a thriving population of stars of all sizes and ages. NASA's Spitzer Space Telescope detected more than 20 bright and dusty galactic mergers like the one depicted here, all teeming with the tiny gem-like crystals.
When galaxies collide, they trigger the birth of large numbers of massive stars. Astronomers believe these blazing hot stars act like furnaces to produce silicate crystals in the same way that glass is made from sand. The stars probably shed the crystals as they age, and as they blow apart in supernovae explosions.
At the same time the crystals are being churned out, they are also being destroyed. Fast-moving particles from supernova blasts easily convert silicates crystals back to their amorphous, or shapeless, form.
How is Spitzer seeing the crystals if they are rapidly disappearing? Astronomers say that, for a short period of time at the beginning of galactic mergers, massive stars might be producing silicate crystals faster than they are eliminating them. When our own galaxy merges with the Andromeda galaxy in a few billion years, a similar burst of massive stars and silicate crystals might occur.
Crystal Storm in Distant Galaxy
The graph (see inset above) of infrared data from NASA's Spitzer Space Telescope tells astronomers that a distant galaxy called IRAS 08752+3915 is experiencing a storm of tiny crystals made up of silicates. The crystals are similar to the glass-like grains of sand found on Earth's many beaches.
The data were taken by Spitzer's infrared spectrograph, which splits light open to reveal its rainbow-like components. The resulting spectrum shown here reveals the signatures of both crystalline (green) and non-crystalline (brown) silicates.
Spitzer detected the same crystals in 20 additional galaxies, all belonging to a class called ultraluminous infrared galaxies. These extremely bright and dusty galaxies usually consist of two galaxies in the process of smashing into each other. Astronomers believe massive stars at the hearts of the galaxies are churning out clouds of silicate crystals. This phenomenon may represent a short-lived phase in the evolution of galactic mergers.
(19 voti)
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MOON OVER VIENNA.jpgSolar eclypse over Vienna85 visiteUn'immagine bellissima: non servono altri commenti.
(19 voti)
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Titan-Huygens Lens.jpgThe Discovery of Titan78 visiteIl 25 Marzo 1655 l'Astronomo Olandese Christiaan Huygens scopriva "Luna Saturni" - ossìa Titano. In questo frame vediamo tutto ciò che resta del telescopio che egli usò (nota: telescopio concepito e costruito in collaborazione con suo fratello, Constantijn Huygens): la lente. Essa ha un diametro di 57 mm e reca sul bordo la dicitura "X 3 FEBR. MDCLV": si tratta della lunghezza focale e della data di completamento del lavoro (e cioè la "lucidatura" della lente stessa): il 3 February 1655.
Si leggono altresì (in alto) questi versi di Ovidio, "Admovere Oculis Distantia Sidera Nostris". Un pizzico di romanticismo? No, solo la porzione di un anagramma: un semplice gioco enigmistico (molto comune ai suoi tempi) che riportava alcuni dettagli della sua scoperta (data inclusa). Decodificato e tradotto l'anagramma di Huygens recita "Una luna orbita intorno a Saturno in 16 giorni e 4 ore". Oggi sappiamo che il periodo orbitale di Titano è pari a poco meno di 16 giorni. Titano ha rallentato o Huygens sbagliò i conti?
(19 voti)
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Voyagers-02.jpgMessage in a "Bottle"...81 visiteCaption NASA:" Launched 30 years ago, NASA's Voyager 1 and 2 Spacecraft are now respectively 15 and 12,5 BKM from the Sun, equivalent to about 14 and 11,5 Light-Hours distant. Still functioning, the Voyagers are being tracked and commanded through the Deep Space Network. Having traveled beyond the outer planets, they are only the third and fourth spacecraft from planet Earth to escape toward interstellar space, following in the footsteps of Pioneer 10 and 11.
A 12" gold plated copper disk (a phonograph record) containing recorded sounds and images representing human cultures and life on Earth, is affixed to each Voyager - a Message in a Bottle, cast into the Cosmic Sea.
The recorded material was selected by a committee chaired by astronomer Carl Sagan. Simple diagrams on the cover symbolically represent the Spacecraft's origin and give instructions for playing the disk. The exotic construction of the disks should provide them with a long lifetime as they coast through the interstellar space". MareKromium
(18 voti)
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SOL442-2N165615279EFFA978P1997R0M1-2.jpgDreaming a New Day...83 visite"...Il Sole che tramonta per alcuni, per altri è il Sole che sorge..."
(anonimo)MareKromium
(18 voti)
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TwentythreeBC.jpg23 Million Years B.C.80 visiteMareKromium
(18 voti)
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SOL694-2P187972203EFFAKBAP0050L7M1~0.jpgDawn on Mars71 visitenessun commento
(18 voti)
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MoonoverAntarctica.jpgAlien Landscape (Moon over Antarctica)126 visiteDa "NASA - Picture of the Day" del 25 Novembre 2005:"Last week, the nearly Full Moon set along the Northern Horizon - as seen from Davis Station, Antarctica. The squashed orange pumpkin shape just silhouettes the peak of a distant iceberg in this stunning view.
The Moon's apparently squashed shape is due to atmospheric bending of light or refraction - an effect which is more severe closer to the horizon. Skimming low along the stark features of the frozen landscape, the Moon's lower edge appears noticeably more distorted than the upper limb. Along with about 70 others present at Davis Station, Dr. Jim Behrens had a chance to enjoy the view while studying the ongoing detachment of a large iceberg known as "Loose Tooth".
(18 voti)
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SolarHalo-2-MF.jpgSolar Halo (credits: Dr Marco Faccin)85 visitenessun commentoMareKromium
(17 voti)
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SolarHalo-3-MF.jpgSolar Halo (credits: Dr Marco Faccin)98 visitenessun commentoMareKromium
(17 voti)
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