Amateur astronomers may want to dust off their telescopes Tuesday because Venus will pass in front of the sun in an event that NASA says only comes once every hundred years or so.

Beginning around 5:09 today, Venus will start its journey across the face of the sun in what’s being called the ‘Transit of Venus’ by scientists. The entire event will take seven hours to complete. Observers will be able to see a small black dot glide from left to right across the top of the sun.

According to NASA, this celestial event is very rare and last occurred 129 years ago. It won’t happen again until December 2117. In fact, the event itself has only happened seven times since the telescope was even invented.

If weather holds, skywatchers on all seven continents should be able to observe. Of course, officials warn against viewing with the naked eye. Instead, consider using a pinhole camera or solar filters on a telescope for the safest view.

[ABC News Radio]