Eighteen hours before my Catalina Sky Survey teammate Rose Matheny first spotted a small space rock with our Schmidt telescope on Mt. Bigelow, Arizona it had passed less than the Earth's diameter from the surface of our planet. Rose was able to discover this Smart Car sized space rock after it moved out of the Sun's glare. At this point it was about the Moon's distance from her and was traveling away at 3.4 mi/s. After Rose posted her discovery observations on the Minor Planet Center's Near Earth Object Confirmation page, for the next 24 hours it was tracked by telescopes in Spain, Illinois, and Arizona. Scientists at the Minor Planet Center used these data to calculate it's orbit around the Sun, estimate it's size and give it the name 2017 UJ2. This small asteroid had come near the Earth in 1978 but was invisible to the technology which astronomers had available at the time. 2017 UJ2 will not come close enough for us to detect in the foreseeable future, however, there are likely to be tens of millions of others like it which can come close to Earth. A small asteroid the size of Rose's discovery is likely to enter our atmosphere at least once a year and explodes at about 4 times higher than airliners fly. If such an event happened at night and you were lucky enough to see it you would be treated to a fantastic light show. If you are as lucky as a power ball winner you might even be able to find a piece of it on the ground.