No, there is no proof of encountering a cosmic cloud. Some scientists believe that, from time to time, our planet could have encountered smaller, less dense clouds of hydrogen, known as the Local Fluff. These less-devastating encounters, according to the models, would have only weakened the heliosphere, with slight increases in cosmic rays hitting Earth.

One of the known side effects of cosmic rays striking Earth is the production of the rare metal beryllium. An increase of this metal could be proof that we had encountered one of these relatively benign clouds. Ice cores taken from the South Pole do indeed show an increase in beryllium levels at approximately 35,000 and 60,000 years ago, leading scientists to speculate that contacts were made with Local Fluff. What are the effects of these minor encounters? Scientists speculate that the effect of Earth coming into contact with the Local Fluff might have produced anything from an ice age to an increased greenhouse effect.