Astronomers from the University of Arizona say they've discovered a mini-moon orbiting the earth. They shared images of the object discovered on Halloween last year from a telescope atop Mt. Bigelow in southern Arizona. The image shows the mini-moon passing through the constellation of Aries. Researchers say the new and perhaps temporary minimoon is probably between 1.9 meters and 3.5 metres across, which is around the same size as a mid-size car. The object is not expected to impact earth, it will eventually burn up harmlessly in the earth's upper atmosphere.