> The sun produces a plasma of charged particles called the solar wind, which get blown supersonically from its atmosphere at more than 1 million km/h.
On earth, that'd be 'supersonic', by a "slim margin". But what's that even mean in space?
On earth, that'd be 'supersonic', by a "slim margin". But what's that even mean in space?
http://en.wikipedia.org/wiki/Heliosphere#Termination_shock expands on this somewhat.
Also: "the spacecraft’s instruments indicated that particles around it were moving subsonically"
lolwut?
Actually, supersonic simply refers to anything moving faster than the speed of sound in a particular medium. The Earth's atmosphere has a particular speed of sound but so does the solar atmosphere and wind. Apparently, the speed of sound in the solar wind is roughly 220,000 mph. Supersonic and subsonic are the terms that scientists use to describe such things.
and then links to this...
http://iopscience.iop.org/0004-637X/623/1/511/fulltext/61043...
Perhaps I'm biased by my own ignorance, but the speed of sound in the solar wind (or the fact that terms like "speed of sound" still make sense in an ostensible vacuum) seems like the sort of thing a reasonable person might not know. If science writing is to be accessible to the layperson, an explanatory parenthetical (even just clarifying the approximate speed at which the subsonic wind was traveling) would have been helpful.
Thanks for the downvote, though.