Keith Urban Ditches Wedding Ring in First Sighting Since Divorce Bombshell

Keith Urban just surfaced for the first time since that Nicole Kidman divorce bombshell dropped -- and yep, the ring’s already MIA!

Peep the pics -- Keith touched down Thursday in Hershey, PA on a private jet, headed straight for Giant Center, where he's performing this evening on tour ... so work mode’s clearly still on, even while he’s dealing with the divorce drama.

Keith stepped off the jet rocking a black cap and shades, bag in hand with his ringless wedding finger -- making it pretty loud and clear: he and Nicole are officially done.

Clearly, Keith’s throwing himself into work ... especially since sources close to the couple told TMZ they think the 57-year-old rocker’s going through a full-blown midlife crisis.

Insiders also told us they believe Keith’s already moved on with another woman... and a clip of him pointing and singing to his guitarist Maggie Baugh from his April Vegas performance is stirring the pot -- although nothing has been proven.