The planet Venus crossed in front of the sun at a slow pace on Tuesday, marking the final visible transit from Earth for the next 105 years. Transits of Venus occur in pairs every eight years, with over a century between cycles. During this recent transit, Venus appeared as a small black dot moving slowly across the sun's northern hemisphere. Many people observed the six-hour and 40-minute event online, with numerous websites offering live video feeds from different locations worldwide. Detailed images from the Prescott Observatory in Arizona, featured on Slooh.com's webcast, captured a small solar flare beginning just below Venus' silhouette. The transit that took place on Tuesday marked the completion of a pair of transits that occurred between 2004 and 2012. It began at 6:09 p.m. EDT (2209 GMT), and observers from all seven continents, including Antarctica, were able to witness at least part of the event. Astronauts on the International Space Station also had the opportunity to view the transit, with flight engineer Don Pettit mentioning that he had been preparing for it for a while and brought a solar filter along for the occasion. It's not just about aesthetics. Numerous scientific experiments were planned, 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 currently being utilized to locate extrasolar planets that transit in front of their host stars, similar to Venus passing in front of the sun. Astronomers intended to analyze Venus's dense atmosphere during its transit in hopes of developing methods to study atmospheres of other planets. Additionally, studying Venus's atmosphere could provide insight into the differences between Earth and Venus, despite their similar size and distance from the sun. Venus has a very thick atmosphere, which is mostly carbon dioxide and 100 times denser than Earth's atmosphere. The planet's surface temperature reaches a scorching 900 degrees Fahrenheit (480 degrees Celsius) and it is covered with clouds of sulfuric acid that move at 220 miles per hour, causing acid rain. Despite being known as the goddess of love, Venus is not a planet you would want to get close to. Scientists are studying Venus' climate 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 the planets. The upcoming transit on Tuesday will be the eighth since the telescope was invented and the last until December 10-11, 2117. This will also be the first transit to occur with a spacecraft present at Venus. Data collected from Europe's Venus Express probe will be analyzed alongside observations from various ground and space-based telescopes, such as NASA's Solar Dynamics Observatory, the US-European Solar and Heliospheric Observatory, and Japan's Hinode spacecraft.