On Tuesday, the planet Venus crossed in front of the sun in a slow transit, marking the last time this event will be visible from Earth for 105 years. Transits of Venus occur in pairs eight years apart, separated by over a century. During this recent transit, Venus appeared as a small black dot moving slowly across the northern part of the sun. Many people watched the event online through various websites that provided live video feeds from different locations. Close-up images from the Prescott Observatory in Arizona, featured on Slooh.com's webcast, captured a small solar flare forming just below Venus. Tuesday's transit started at 6:09 p.m. EDT (2209 GMT) and marked the completion of a pair that occurred between 2004 and 2012. People from seven continents, including Antarctica, were able to witness the event, and even astronauts on the International Space Station were able to view it. Don Pettit, a flight engineer on the space station, had been preparing for this event and brought a solar filter with him in anticipation of the transit of Venus occurring during his rotation. It's not just about beautiful images. Multiple scientific experiments were scheduled, including research that could aid in the discovery of potentially habitable planets outside of our solar system. Telescopes like NASA's Kepler space telescope are being utilized to identify extrasolar planets that transit in front of their host stars, similar to Venus passing in front of the sun. During the Venus transit, astronomers intended to analyze the planet's dense atmosphere in order to develop methods for studying atmospheres of other planets. Research on Venus's atmosphere could also provide insight into the differences between Earth and Venus, despite their similar size and orbital distance from the sun. Venus has a very thick atmosphere, which is mostly carbon dioxide, and its surface temperature is extremely hot. The planet experiences acid rain from sulfuric acid clouds moving at high speeds. Despite being known as the goddess of love, Venus is not a place you would want to visit. Scientists are studying Venus to gain insight into changes in Earth's atmosphere. In past transits of Venus, scientists determined the size of the solar system and the distance between the sun and planets. This upcoming transit on Tuesday will be the eighth since the telescope was invented and the last until December 10-11, 2117. It will also be the first transit with a spacecraft at Venus, allowing for observations to be compared with data from various telescopes, including NASA's Solar Dynamics Observatory, the US-European Solar and Heliospheric Observatory, and Japan's Hinode spacecraft.