This is one of those events where I simply don't have that much to say. A big asteroid, discovered in 1998, will be passing by the Earth tomorrow at a distance of less than 6 million kilometers. If an asteroid that size were to hit Earth, we'd all be in huge trouble, but we don't have to worry about this one because we know it's not coming anywhere near us. Although 6 million kilometers is practically on our doorstep, in Solar System terms, it's still 15 times further away than the Moon. The South African Astronomical Observatory has a great deal more to say on the subject:
Although the asteroid will not be visible with the naked eye as it will be too faint, it will be visible using a small telecope. Professional radar astronomers in particular, are eagerly looking forward to the flyby as it will provide them with a chance to study the asteroid in detail using radio telescopes. Astronomers are planning to use images from the largest radio dish in the world, the Arecibo radio telescope in Puerto Rico which has a diameter of 305 metres! They will also be using images from NASA's 70 metre Deep Space Network radio dish at Goldstone Observatory in California. Using these telescopes astronomers will be able to resolve features on the asteroid as small as 3.75 metres across, even from 6 million kilometers away!
You can read a great deal more on their announcement page, and I recommend that you do because they have included a live video stream of the asteroid so that you can watch it as it passes us by!