Although the vacuum of space is sparser than any vacuum we can yet create in the laboratory, it is not completely devoid of any matter, and I find it fascinating how interstellar gas can have real, observable effects. In fact, there can even be sound in the vacuum of space, even if they are the sort that our human ears could never hear.
Given my fascination, it is no surprise that my attention would be drawn to news that a debris disk around a young star may be deformed because of interstellar gas. A deformed debris disk might indicate the presence of a planet as was the case for Fomalhaut b. However, the debris disk around a star like HD 61005 may instead be deformed due to pressure from the interstellar gas as the young star system travels through interstellar space. It would be like how smoke trails behind as a steam locomotive speeds by.
If confirmed, this would be another example of how something any of us would call a vacuum is not quite a vacuum.