Throughout history small close approaching space rocks have been a part of our environment. Now, thanks to improved telescopes and cameras, asteroid hunters are routinely discovering these small asteroids as they pass closer than the Moon is to us. Since these tiny asteroids are only bright enough to detect for a few days out of their long, many month duration paths about the Sun, astronomers have had difficulty in determining how many of these small space rocks may exist in near Earth space. This effort received more emphasis when a house sized space rock exploded over Chelyabinsk, Russia in 2013 releasing about 10 times the energy of the Hiroshima atomic bomb. Although this asteroid was tiny compared to the one that ended the dinosaurs rule of the planet, the air blast the Chelyabinsk bolide produced caused nearly 1,500 human injuries and damaged more than 7,000 buildings. In a 2017 paper in the Astronomical Journal, Dr. David Trilling of Northern Arizona University and his group of researchers present data from the Blanco 4 meter telescope at the Cerro Tololo Inter-American Observatory in Chile which they use to estimate that there are approximately 3.2 million Earth approaching asteroids similar in size to the Chelyabinsk impactor. My team the Catalina Sky Survey uses 4 telescopes, 24 nights per month, in the mountains north of Tucson, Arizona with the goal to provide warnings for people to stay away from doors and windows should a Chelyabinsk sized space rock be on an impact trajectory with planet Earth.
