Forum AstroNamur ASBL - Astronomie Amateur

Forum de discussion d'AstroNamur
 
AccueilAccueil  PortailPortail  RechercherRechercher  S'enregistrerS'enregistrer  Connexion  
Le Deal du moment : -43%
Braun Tondeuse À Barbe BT3041
Voir le deal
28.59 €

Partagez
 

 Les nuages noctiluques sont de retour

Aller en bas 
AuteurMessage
Admin
Neptune
Admin

Nombre de messages : 4692
Date d'inscription : 21/07/2005
Localisation : Namur, Salzinnes

Les nuages noctiluques sont de retour Empty
MessageSujet: Les nuages noctiluques sont de retour   Les nuages noctiluques sont de retour EmptyDim 31 Mai 2009 - 7:38

Space Weather News for May 30, 2009
http://spaceweather.com

FIRST NLCs of 2009: The first noctilucent clouds (NLCs) of 2009 have been sighted over northern Europe. Last night, May 29th, photographers recorded wispy electric-blue tendrils spreading across the twilight skies of Denmark, Northern Ireland and Scotland. This follows a similar display over Russia on May 27th. These sightings signal the beginning of the 2009 NLC season, which is expected to last until late July. Early-season NLCs are usually feeble, but these were fairly bright and vibrant, suggesting that even better displays are in the offing. Check today's edition of http://spaceweather.com for photos.

Noctilucent clouds are an unsolved puzzle. They float 83 km above Earth's surface at the edge of space itself. People first noticed NLCs in the late 19th century. In those days you had to travel to high northern latitudes to see them. In recent years, however, the clouds have been sighted in the United States as far south as Oregon, Washington and even Colorado. Climate change, space dust, and rocket launches have all been cited as possible explanations for the phenomenon. Interestingly, low solar activity seems to promote the clouds, so the ongoing deep solar minimum could set the stage for a good season in 2009.

The best time to look for NLCs is just after sunset or just before sunrise when the sun is between 6 and 16 degrees below the horizon. That's when the geometry is just right for sunlight to illuminate the tiny ice crystals that make up the clouds. Observing tips and sample photos may be found in the 2008 Noctilucent Cloud Gallery:

http://spaceweather.com/nlcs/gallery2008_page10.htm

Readers, if you enjoy these newsletters and wish to support our efforts, please consider signing up for Spaceweather.com's astronomy alert service: http://spaceweatherphone.com . Thanks!
Revenir en haut Aller en bas
 
Les nuages noctiluques sont de retour
Revenir en haut 
Page 1 sur 1

Permission de ce forum:Vous ne pouvez pas répondre aux sujets dans ce forum
Forum AstroNamur ASBL - Astronomie Amateur :: Le forum :: Actualités générales-
Sauter vers: