Sfrecciando nei cieli sopra il Paranal
L’Immagine della Settimana di oggi è un maestoso ritratto dell’UT4, uno dei quattro telescopi lunghi otto metri del VLT (Very Large Telescope) dell’ESO. Incorniciato dal cielo stellato sopra l’Osservatorio del Paranal, questo telescopio è molto più di un banale osservatore passivo. Dall'interno della sua cupola, squarcia la tranquilla notte con quattro raggi laser.
Questi laser vengono proiettati dal 4 Laser Guide Star Facility (4LGSF), di cui si serve l’UT4 per creare nel cielo le sue stelle artificiali. I laser creano questi punti luminosi eccitando gli atomi di sodio nell’atmosfera, a circa 90 km sopra il livello del suolo, facendoli brillare. Queste “stelle” fungono quindi da guida, poiché solo studiando come vengono oscurate dall’atmosfera che il telescopio impara come regolare la turbolenza atmosferica – la stessa turbolenza che fa brillare ogni piccola stella.
Ogni adattamento è fatto dal sistema ottico adattivo dell’UT4, che è in grado di deformare con precisione lo specchio secondario del telescopio per annullare i disturbi atmosferici misurati dal sistema. Grazie all'ottica adattiva, un telescopio terrestre può può scattare immagini più limpide di quanto l’atmosfera permetterebbe normalmente – è valido quasi quanto inviare il VLT nello spazio.
Presto, ciascuno degli altri telescopi alti 8 metri del VLT avrà un laser, come parte di una serie di aggiornamenti dell’interferometro del VLT e del suo strumento GRAVITY+, che può combinare le luci di diversi telescopi per creare uno “virtuale” più grande. Un altro immenso occhio nel cielo, l’Extremely Large Telescope dell’ESO (ELT), sta per essere ultimato non molto lontano dal Paranal, e sarà dotato con almeno 6 lasers, per restituire immagini il più nitide possibili con un telescopio di terra.
Crediti:ESO/A. de Burgos Sierra
Riguardo l'immagine
| Identificazione: | potw2516a |
| Lingua: | it-ch |
| Tipo: | Fotografico |
| Data di rilascio: | Lunedì 21 Aprile 2025 06:00 |
| Grandezza: | 5239 x 3493 px |
Riguardo all'oggetto
| Nome: | Laser Guide Star, Very Large Telescope |
| Tipo: | Unspecified : Technology : Observatory |
Formati delle immagini
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