Starship Asterisk*

The Local Fluff

Explanation: The stars are not alone. In the disk of our Milky Way Galaxy about 10 percent of visible matter is in the form of gas, called the interstellar medium (ISM). The ISM is not uniform, and shows patchiness even near our Sun. It can be quite difficult to detect the local ISM because it is so tenuous and emits so little light. This mostly hydrogen gas, however, absorbs some very specific colors that can be detected in the light of the nearest stars. A working map of the local ISM within 20 light-years, based on ongoing observations and recent particle detections from the Earth-orbiting Interstellar Boundary Exporer satellite (IBEX), is shown above. These observations indicate that our Sun is moving through a Local Interstellar Cloud as this cloud flows outwards from the Scorpius-Centaurus Association star forming region. Our Sun may exit the Local Cloud, also called the Local Fluff, during the next 10,000 years. Much remains unknown about the local ISM, including details of its distribution, its origin, and how it affects the Sun and the Earth. Unexpectedly, recent IBEX spacecraft measurements indicate that the direction from which neutral interstellar particles flow through our Solar System is changing.

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We are a drift in a sea...and the currents are changing around us...

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Are we to assume that the arrows are vector quantities, i.e., they have magnitude as well as direction? Or are they simply scalar quantities?

PacRim Jim wrote:Are we to assume that the arrows are vector quantities, i.e., they have magnitude as well as direction? Or are they simply scalar quantities?

From the IBEX homepage "the direction of motion of the various gas clouds are depicted by arrows". The arrows are thus vectors, not pointers to particular places and no scalar quantities.

Is it possible that the void behind our sun, was created by its motion through the cloud?

inertnet wrote:
Is it possible that the void behind our sun, was created by its motion through the cloud?

The void behind our sun (created by its motion through the cloud) is an elongated narrow tail less than a pixel wide in today's APOD.

I found the link to the January 31, 2012 NASA IBEX briefing, from which this illustration is drawn, helpful in getting oriented and understanding this image.

Visual 4 is a youtube video that zooms in from high above the Milky Way Galaxy onto the Sun in our immediate interstellar neighborhood.

Visual 8 is another video that shows where the interstellar wind is coming from in the sky as seen from Earth -- the Scorpius-Centaurus association.

Visual 16 is a still image that shows the other nearby stars that are known to have heliospheres (areas where the star's own solar wind clears out a little nest within the interstellar wind, decreasing the density of cosmic rays) and/or planets -- i.e. analogues of our own solar system.

Hmm, 4, 8, 16 -- I think the aliens may be trying to tell us something!

For such a tenuous cloud of gas, this is a very dense subject!

Anthony, the Aliens are always trying to tell us something, but most of us miss most of it.

Anthony Barreiro wrote:For such a tenuous cloud of gas, this is a very dense subject!

HA! I'm feeling a little dense just thinking about Tenuousness.

Clicking on the APOD image brings up a slightly wider field-of-view that also has a distance scale in light-years.

DavidLeodis wrote:
Clicking on the APOD image brings up a slightly wider field-of-view that also has a distance scale in light-years.

If this represents a cube 50 light years on a side then there should be ~2500 stars in there (according to there being about 1 star per 50 cubic light-years in the general neighborhood of the Sun). Assuming that most of these stars are faint red dwarfs I guess that is possible.

In any event, the average star density of small dwarf galaxy M60-UDC1 is 5,000 times higher than this