A rare interstellar comet — only the third ever confirmed to enter our solar system — was photographed last week, closely approaching Mars, the European Space Agency said Tuesday.  The images taken on Friday by two Mars orbiters show a bright, fuzzy white dot of the comet, also known as 3I/ATLAS , appearing to move against a backdrop of distant stars as it was about 18,641,135 miles away from Mars. The comet poses no threat to Earth, NASA has previously said.  "This was a very challenging