Basic physics says it shouldn't be there

Dec 29, 2009 11:32 GMT  ·  By
Voyager flies through the outer bounds of the heliosphere en route to interstellar space. A strong magnetic field is delineated in yellow
   Voyager flies through the outer bounds of the heliosphere en route to interstellar space. A strong magnetic field is delineated in yellow

As the planets swirl around the Sun, the entire solar system is passing at this point through a huge interstellar cloud called the Local Fluff. The problem with this is the fact that basic physics dictates that the cloud shouldn't be there. This inconsistency doesn't actually stop the cloud from being there, so astronomers have been wondering how come its existence is possible for many years. Now, a group of NASA researchers, using data from the Voyager spacecraft, managed to find the elusive answer.

According to Space Fellowship, the twin probes were able to determine how the cloud remained in one piece when it shouldn't have. “Using data from Voyager, we have discovered a strong magnetic field just outside the solar system. This magnetic field holds the interstellar cloud together and solves the long-standing puzzle of how it can exist at all,” the lead author of the new study, Merav Opher, explains. The expert is based at the George Mason University, and also holds an appointment as a NASA Heliophysics guest investigator. Details of the team's work appear in the December 24 issue of the esteemed scientific journal Nature.

One of the reasons why the existence of the Local Interstellar Cloud was so mysterious was because, millions of years ago, a large cluster of supernovas exploded in the vicinity of our solar system. This massive explosion triggered the formation of a high-pressure supernova exhaust, a cloud of gas heated to millions of degrees. The Local Fluff is entirely surrounded by these remnants, and should have therefore been dispersed or destroyed a long time ago. However, it would now appear that the strong magnetic field outside our solar system is keeping the helium and hydrogen atoms, all heated to about 6,000 degrees Celsius, in check.

“The observed temperature and density of the local cloud do not provide enough pressure to resist the ‘crushing action’ of the hot gas around it. Voyager data show that the Fluff is much more strongly magnetized than anyone had previously suspected – between 4 and 5 microgauss. This magnetic field can provide the extra pressure required to resist destruction. The Voyagers are not actually inside the Local Fluff. But they are getting close and can sense what the cloud is like as they approach it. There could be interesting times ahead!” Opher says.