(NEW YORK) -- If you look up in the sky on Tuesday you may be in for a once in a lifetime treat.
Starting at around 6:09 p.m. Eastern Daylight Time, Venus will start to pass in front of the sun, leaving a beauty mark-like spot on the sun. The "Transit of Venus," as its called, will take about seven hours to complete.
According to NASA, the event is "very rare, coming in pairs separated by more than a hundred years." Tuesday's transit will be the last one seen until 2117.
Weather permitting, observers on all seven continents will be able to see the event, NASA says. The space agency warns viewers not to see the phenomenon with their bare eyes, as it can cause permanent damage.
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