Where does it come from, how is it appointed to a particular rider and what criteria does one have to meet to be an "alien"? Thanks.

It was Random Randy De Puniet who came up with that nickname about a year ago.
http://www.motogp.com/en/news/2009/de+puniet+5th+fastest+at+catalunya+gp+opening+day
http://www.motomatters.com/report/2009/07/23/2009_motogp_sachsenring_race_report_alie.html

surprisingly the criteria to be an alien in 2009 was to beat colin edwards

Thank ya Lucky! Yeah, too bad about Colin. I wonder if they'll keep him next year or if he even wants to return?

MCN are running with a 'edwards back to wsb on ducati' story this week... which if true means that haga's prob back with Yamaha....

desperation for glory from both bologna & CE, no?!

after so many years just making up the numbers in MotoGP, can't say I blame CE if he went to WSB for a bit of glory before pulling the plug. Could end up being nasty if he ain't competitive tho

if CE makes a good WSB showing then fair play... but the ducati seems to be at the end of it's current design parameter... the 4s may have 200cc less but they make more bhp & the electrics package makes then ridable...

off the top of my head, only Kocinski & Bayliss have ever made a sucessful downgrade from gp to WSB

(using criteria of success is regular podium finhes, the odd race win & a relatively lucky championship) the only bloke ever to make good in motogp from a superbike is hayden

'bloke ever to make good in motogp from a superbike is hayden'
You missed a couple:
Wayne Rainey 1983, 1987 AMA Superbike Champion 3 Time GP Champion
Eddie Lawson 1981, 1982 AMA Superbike Champion. 4 Time GP Champion
Kevin Schwantz, 2nd to Wayne AMA 1987 and GP Champion 1993.
John Kocinski won a few races and was on the podium a few times.
Colin's been on the podium a few times as was Doug Chandler. Next up: Mr. Spies!