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Énorme explosion détectée à la surface d’Uranus

Publié par wikistrike.over-blog.com sur 3 Novembre 2011, 01:35am

Catégories : #Astronomie - Espace

 

Énorme explosion détectée à la surface d’Uranus


111028-UranusPhoto-hmed-0315p.grid-6x2.jpg

 

Les scientifiques sont excités. Ils ont observé une énorme explosion sur Uranus et ils se demandent ce que ça peut être et pourquoi elle a eu lieu. 

Ils ont 2 bonnes raisons d’être excités : la première, Uranus est une des planètes la moins bien connue à cause de sa grande distance par rapport à la Terre. La deuxième, c’est la planète la plus ennuyeuse du système solaire (sa seule particularité, c’est que son axe est presque à l’horizontale par rapport au Soleil)…

Aujourd’hui, Uranus est étonnante parce qu’une énorme explosion est visible à sa surface. Les nuages sur Uranus semblent répondre à une saisonnalité. Comme Uranus tourne de côté, il y a des changements extrêmes de température à sa surface selon les périodes de l’année. Et les changements sont bien plus dramatiques que sur d’autres planètes. En étudiant Uranus, on étudie l’équilibre d’énergie de l’atmosphère d’une planète.

Si en plus, on considère que l’hémisphère nord d’Uranus est ensoleillé pendant 42 ans de suite et que le sud est dans l’ombre. Cette planète lointaine devient beaucoup moins ennuyeuse avec le temps qui passe.

 

Eruption on 'boring' Uranus excites world of astronomy

Scientists hope controllers of Hubble Space Telescope will take a closer look

 

By Mark Thompson

Of all the planets in our solar system, I'm usually guilty of thinking poor old Uranus is pretty bland and uninteresting.

In fact, the only interesting things I can ever think to say about it are that it orbits the sun on its side... and has a pretty exciting story attached to its discovery.

Other than that, well... let's look at Neptune instead. NO, WAIT! Something exciting has happened on Uranus!

Uranus, like the other giant planets in the solar system (Jupiter, Saturn and Neptune), is made up almost entirely of gas, although it differs in composition to Jupiter and Saturn — it has higher quantities of water, methane and ammonia ices. Unlike conventional ice, it's a super dense liquid. Uranus, like Neptune, is often referred to as an "ice giant."

Uranus measures a mighty four-times the diameter of Earth and orbits the sun at an average distance of 2.9 billion kilometers (around 20 times the Earth-sun distance). From that distance it's only just visible to the naked eye under dark skies, but telescopes are needed to see any detail.

Nearer planets seem to receive more attention from amateur astronomers but that may be about to change.

An image taken by planetary scientist Larry Sromovsky, with the Gemini 8.1 meter telescope, shows a bright patch that is thought to be an eruption of methane ice high in the atmosphere.

Leading planetary scientist Heidi B. Hammel used her Facebook page to announce the discovery and to appeal for further observations. Amateur astronomers with advanced equipment are being asked to make observations of the planet and, if enough confirmations are received, it may lead controllers of the Hubble Space Telescope to interrupt observations and take a closer look.

Understanding the nature of this spot is important, Hammel explained to Discovery News.

"The reason we care about the clouds on the planet Uranus is that they seem to be seasonally driven," said Hammel. "Uranus spins tipped over on its side, giving rise to extreme changes in sunlight as its seasons progress.

"The changes are therefore much more dramatic than for other planets. Uranus thus gives us unique insight into the energy balance in a planetary atmosphere."

It's almost like a weather system on steroids, as the northern hemisphere receives 42 years of sunlight and constant energy from the sun with the southern hemisphere plunged into 42 years of darkness.

Unfortunately, this new outburst may be just out of reach of most amateur astronomers but those with more advanced equipment should certainly take a look.

It seems fitting that 230 years since the planet was discovered by Hesrchel, himself an amateur astronomer, it may be the work of modern day amateurs that unlock clues to the nature of Uranus' strange atmospheric effects.

© 2011 Discovery Channel

 

Source : 2012 paradigme

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