GIANT RIBBON DISCOVERED AT THE EDGE OF THE SOLAR SYSTEM

For years, researchers have known that the solar system is surrounded by a vast bubble of magnetism. Called the "heliosphere," it springs from the sun and extends far beyond the orbit of Pluto, providing a first line of defense against cosmic rays and interstellar clouds that try to enter our local space. Although the heliosphere is huge and literally fills the sky, it emits no light and no one has actually seen it. Until now.

NASA's IBEX (Interstellar Boundary Explorer) spacecraft has made the first all-sky map of the heliosphere and the results have taken researchers by surprise. The map is bisected by a bright, winding ribbon of unknown origin:

"This is a shocking new result," says IBEX principal investigator Dave McComas of the Southwest Research Institute. "We had no idea this ribbon existed--or what has created it. Our previous ideas about the outer heliosphere are going to have to be revised."

The two Voyager spacecraft (labeled V1 and V2 in the figure) have spent decades traveling to the edge of the solar system for in situ inspection of whatever might be there--but ironically both spacecraft missed the ribbon. "It's like having two weather stations, but missing the big storm that runs between them," says Eric Christian, IBEX deputy mission scientist at NASA's Goddard Space Flight Center.

At the moment, theorists are "working like crazy" to understand this discovery and how the ribbon might effect the ability of the heliosphere to shield us from cosmic rays. Science@NASA has the full story.

SOLAR FLARE:

New-cycle sunspot 1026 is crackling with magnetic activity, and this morning it produced a C-class solar flare. The Solar and Heliospheric Observatory's (SOHO's) extreme UV telescope recorded the action around 0100 UT on Sept. 25th:

If you thought that flare seemed small, you were right. It was about 100-times too weak too affect Earth. During Solar Maximum, such a minor eruption would probably go unnoticed and certainly unmentioned. But during the deepest solar minimum in almost 100 years, it's a big event. A C-flare! The blast raised no radio blackouts or radiation storms--only the hopes of solar observers for something more flamboyant. Stay tuned.

SOLAR MINIMUM VS. GLOBAL WARMING

From 2002 to 2008, decreasing solar irradiance has countered much anthropogenic warming of Earth's surface. That's the conclusion of researchers Judith Lean (NRL) and David Rind (NASA/GISS), who have just published a new analysis of global temperatures in the Geophysical Research Letters. Lean and Rind considered four drivers of climate change: solar activity, volcanic eruptions, ENSO (El Nino), and the accumulation of greenhouse gases. The following plot shows how much each has contributed to the changing temperature of Earth's surface since 1980:


Volcanic aerosols are a source of cooling; ENSO and greenhouse gases cause heating; the solar cycle can go either way. When added together, these factors can account for 76% of the variance in Earth's surface temperature over the past ~30 years, according to the analysis of Lean and Rind.

Several aspects of their model attract attention: "The warmest year on record, 1998, coincides with the 'super-El Nino' of 1997-98," points out Lean. "The ESNO is capable of producing significant spikes in the temperature record." Solar minimum has the opposite effect: "A 0.1% decrease in the sun's irradiance has counteracted some of the warming action of greenhouse gases from 2002 - 2008," she notes. "This is the reason for the well-known 'flat' temperature trend of recent years."

What's next? Ultimately, the authors say, temperatures will begin rising again as greenhouse gases accumulate and solar activity resumes with the coming of the next solar cycle. Of couse, the solar cycle could be out of whack; if solar minimum deepens and persists, no one is certain what will happen. Lean and Rind reveal their predictions for the future here.

Reference: Lean, J. L., and D. H. Rind (2009), How will Earth's surface temperature change in future decades?, Geophys. Res. Lett., 36, L15708
(Source: www.spaceweather.com)

Nivelul actual al activitatii solare

Nivelul actual al activitatii solare este scazut. O regiune mica de flux magnetic a aparut la suprafata vizibila in partea de SV a Soarelui, in ultimele doua zile. Regiunea contine doua pete noi formate si cateva bucle coronale vizibile in EUV. Pozitia aproximativa a regiunii este S08W45, ( 669", -81" ) pe 28 aprilie 2009, ora 10:00 UT.

Eclipsa inelara de Soare

Prima eclipsa din anul 2009 este o eclipsa inelara de Soare. Aceasta este vizibila, ca eclipsa inelara, in Oceanul Indian, din sudul Africii si pana in vestul Indoneziei, pe un coridor lat de 363 km. Eclipsa este vizibila ca partiala in Madagascar, Australia, sud estul Indiei, sudul Asiei si Indonezia.
Eclipsa inelara incepe in sudul Africii la 06:06 UT. Maximul eclipsei (de 0,9282) se situeaza in Oceanul Indian la 07:58:39 UT si tine 7 minute 54 secunde.
Aceasta eclipsa este al 50-lea membru al ciclului Saros 131, ciclul inceput pe 1 Aug 1125 si va tine 18 Jun 2243.

Heliosfera

Heliosfera reprezintă un spaţiu de influenţă a Soarelui din punct de vedere magnetic, cât şi al activităţii sale manifestată prin vântul solar. Heliosfera are forma unei picaturi {bubble) ce pluteşte în spaţiul interstelar. Atomi neutri din punct de vedere electric, ce vin din mediul interstelar, penetrează heliosfera interacţionând cu aceasta, astfel că există un permanent schimb de materie intre aceasta şi restul Galaxiei.

Văntul solar mătură heliosfera cu o viteză ce poate atinge un milion km/h pe primele 10 miliarde de km pornind radial de la Soare, pentru ca apoi sa îşi încetinească viteza până la epuizare. Zona unde vântul solar înceteaza se numeşte şocul terminal. Zona unde vântul solar şi vântul galactic se echilibrează se numeşte heliopauză. Zona unde influenţa mediului stelar începe să domine asupra vântului solar poartă numele de ‘bow shock’, ceea ce am putea traduce prin front de şoc.

Vântul solar constă într-un flux de particule, atomi ionizaţi şi câmp electromagnetic, flux ce este expulzat de atmosfera solară în spaţiul interplanetar. Datorită rotaţiei diferenţiale a Soarelui, câmpul magnetic transportat de vântul solar ia forma unei spirale tridimensionale, denumită de Parker ‘balerina’, fiind asemanatoare cu jupa unei balerine care se roteşte. Spaţiul interplanetary este împărţit în 2 până la 4 (funcţie de ciclul solar) sectoare magnetice. Aceste sectoare sunt despărţite de graniţe neuter din punct d evedere magnetic, graniţe ce reprezintă de fapt extensia straturilor de current din atmosfera Soarelui. Această structura domină heliosfera interioară.

Structura heliosferei externe este determinată de interactiunea vântului solar cu cel interstelar.

Noutati despre activitatea Soarelui

Soarele se afla la perioada de minim al activitatii sale. La sfarsitul lunii trecute si anume, pe 21 septembrie a aparut o pata solara denumita NOAA 11001.Pe 23 Septembrie, a aparut o alta pata solara denumita NOAA 11002. Ea a putut fi observata pentru aproape 3 zile.

Pe 4 octombrie si-a mai facut aparitia inca o pata (NOAA 11003) cu o durata de viata asemanatoare celei precedente. Pe 10 octombrie isi face aparitia NOAA 11004, iar pe 11 - NOAA 11005.
Reamintim ca pata NOAA 11000 si-a facut aparitia pe 18 iulie, ca ultima pata a ciclului solar 23.

Astfel numarul de pete solare incepe sa varieze putin de la valoarea 0.