Get ready for some huge asteroid whizzing action, because this summer we'll be witnessing 4 large space rocks passing by Earth. In August, kilometer-wide asteroids are slated to miss our home planet, luckily at a safe distance, so the armageddon isn't scheduled and Bruce Willis can stay home. First of the Near Earth Objects (NEO), asteroid 2002 JN97, discovered in May 2002 will pass our planet by 61 lunar distances (LD) on August 2. The rock is estimated to be nearly 3 kilometers wide. It will fly by the Earth at a velocity of 21 km/s
We don't witness asteroids that big, passing by very often. In July there is only one asteroid that could have at least 1 km in diameter predicted to fly by Earth. It is estimated that the July 20 object, 2014 ER49 won't have more than 1200 m. Scientists estimate that several dozen asteroids in the 6-to-12-meter size range fly by Earth at a distance even closer than the moon every year. But only a fraction of these are actually detected.
Mark your calendars for August 17, because this is the day of a real asteroid frenzy. 2001 RZ11 has about 3 km in diameter and among with its 1 kilometer-wide companion, 2013 WT67, will make the day. The rocks will pass the Earth at a safe distance, of course. The first one at 34 LD and the second much closer, but still 16 LD. What is significant, 2001 RZ11 is enlisted as a Potentially Hazardous Asteroid (PHA). Those objects have the potential to make close approaches to the Earth and are of a size large enough to cause significant regional damage in the event of impact. PHAs are space rocks larger than approximately 100 m that can come closer to Earth than 0.05 AU (about 20 LD). There are currently 1489 known PHAs.
Last but not least, on August 30, about 1 kilometer-wide asteroid 2002 CU11 will swing by. At a velocity of 26 km/s, the rock will fly at the closest distance of all the asteroids mentioned above, 13.5 LD. So we can call it potentially hazardous. Next time to see it so close? Aug. 31, 2080, the 2002 CU11 will come closer than 2 LD.
As of July 04, 2014, 11209 Near-Earth objects have been discovered. Some 865 of these NEOs are asteroids with a diameter of approximately 1 kilometer or larger.