Laser-hulpster zwaait langs de sterrenhemel
Een krachtige laserstraal van ESO’s Very Large Telescope (VLT) kleurt de nachtelijke hemel boven de Chileense Atacama-woestijn op deze foto, die is genomen door Julien Girard. Door de rotatie van de aarde gedurende deze opname van 30 minuten – en de beweging van de laser om hiervoor te compenseren - lijkt het alsof de straal uitwaaiert. Hierdoor zijn ook de sterren uitgestrekt tot gebogen strepen, waardoor subtiele verschillen in hun kleur zichtbaar worden.
De laser wordt gebruikt om een punt aan de hemel te creëren – een kunstmatige ster - door natrium-atomen op 90 kilometer hoogte in de atmosfeer van de aarde op te laten lichten. Metingen aan deze hulpster worden gebruikt om te corrigeren voor het vertroebelende effect van de atmosfeer in astronomische observaties – een techniek die bekend staat als adaptieve optiek. Hoewel natuurlijke sterren die helder genoeg zijn ook worden gebruikt voor adaptieve optiek, kan een laser-hulpster overal gepositioneerd worden, wat betekent dat adaptieve optiek kan worden gebruikt voor objecten aan een groter deel van de hemel.
De vier grote koepels van de 8,2-meter Unit Telescopes van de VLT zijn zichtbaar op de foto, met de kleinere VLT Survey Telecope (VST) op de achtergrond. Julien is een ESO-astronoom in Chili, die werkt bij de VLT. In de nacht dat deze foto werd genomen werkte hij aan observaties met de meest rechtse Unit Telescope. Hij maakte gebruik van de gelegenheid om zijn camera en statief klaar te zetten voordat hij terugging naar het gebouw waarvandaan de waarnemingen worden gedaan.
De bewegingen van de koepels van de telescoop gedurende de lange opname zijn ook wazig net als de vage lichtstrepen die gemaakt zijn door mensen die over het platform tussen de telescopen liepen.
Julien voegde deze foto toe aan de Your ESO Pictures Flickr group. De Flickr-groep wordt regelmatig bekeken en de beste foto’s worden geselecteerd voor onze populaire Foto van de week-serie of onze galerij. In 2012 zijn vanwege ESO’s 50-jarig jubileum ook historische ESO-gerelateerde foto’s welkom.
Links
- Deze foto, met toelichting, op Julien Girard’s Flickr photostream
- Julien Girard’s Flickr photostream
- De 'Your ESO Pictures' Flickr groep
- De 'Your ESO Pictures' aankondiging
ESO/J. Girard (djulik.com)
Over de afbeelding
| Id: | potw1234a |
| Taal: | nl-be |
| Type: | Fotografisch |
| Publicatiedatum: | 20 augustus 2012 10:00 |
| Grootte: | 4316 x 2876 px |
Over het object
| Naam: | Very Large Telescope |
| Type: | Unspecified : Technology : Observatory : Facility |
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