The asteroid 2014 JO25 will have a close pass by the Earth at 7:24am Wednesday morning at a distance of about 1.76 million kilometers. That is a very close approach for an asteroid of this size
--but as far as a risk goes, it's no risk at all. The last time a sizable asteroid came by was Toutatis' visit in September 2004; it won't happen again for about ten years.
What's interesting about this pass is the opportunity to gather good data on this object. Sky & Telescope
is predicting a possible maximum magnitude for United States citizens of 10.8.
Here's the rough outline of 2014 JO25's path, in CDT...
Tuesday at 9pm, Cepheus
Wednesday at 2am, Draco
Wednesday at 7am, Draco-Ursa Minor border
Wednesday at 12pm, Boötes-Ursa Major border
Wednesday at 5pm, Canes Venatici
Wednesday at 10pm, Coma Berenices
Thursday at 3am, Coma Berenices-Virgo border
Thursday at 11pm, Virgo
And here are a couple of notable times during 2014 JO25's visit through our skies...
*At 9:30pm CDT on Wednesday night, the asteroid will be almost on top of
41 Comae Berenices, a magnitude 4.8 K-class star. That star will be forty-seven degrees up then.
*At 1am CDT Thursday morning, the asteroid will be very close to M64 (The Black-Eye Galaxy), which will be seven-five degrees up then.