An Indian Saddhu (holy person) watches the transit of Planet Venus across the sun with protective eyewear in Guwahati on June 6, 2012. Sky-gazers around the world held up their telescopes and viewing glasses to watch a once-in-a-lifetime event as Venus slid across the Sun.
- [STRDEL/AFP/Getty Images]

A data capture shows Venus crossing the Sun. The 2012 Transit of Venus, on June 5-6, was the last for 105 years.
- [NASA/SDO, HMI, and AIA science teams/Courtesy]

Joshua Howes, from New York, wears special goggles to observe the Transit of Venus from the High Line park on June 5, 2012 in New York City. The Transit of Venus involves the planet Venus crossing in front of the sun. The next pair of events will not happen again until the year 2117 and 2125. (Photo by Andrew Burton/Getty Images)
- [Andrew Burton/AFP/Getty Images]

A data capture shows Venus crossing the Sun. The 2012 Transit of Venus, on June 5-6, was the last for 105 years.
- [NASA/SDO, HMI, and AIA science teams/Courtesy]

Pakistani students watch the transit of Planet Venus across the sun using welder's masks for eye protection in Lahore on June 6, 2012. Astronomers around the world trained their telescopes on the skies to watch Venus pass in front of the Sun, a once-in-a-lifetime event that will not be seen for another 105 years.
- [ARIF ALI/AFP/Getty Images]

Skywatchers, who gathered to witness the transit of Planet Venus, look through protective eyewear in a futile wait for a break in the clouds during overcast skies in Mumbai on June 6, 2012. Sky-gazers around the world held up their telescopes and viewing glasses to watch a once-in-a-lifetime event as Venus slid across the Sun.
- [INDRANIL MUKHERJEE/AFP/Getty Images]

Planet Venus, pictured as a black dot (at L), is seen in transit across the Sun in New Delhi on June 6, 2012. Sky-gazers around the world held up their telescopes and viewing glasses to watch a once-in-a-lifetime event as Venus slid across the Sun.
- [MANAN VATSYAYANA/AFP/Getty Images]

Planet Venus, pictured as a black dot (at L), is seen in transit across the Sun in New Delhi on June 6, 2012. Sky-gazers around the world held up their telescopes and viewing glasses to watch a once-in-a-lifetime event as Venus slid across the Sun.
- [MANAN VATSYAYANA/AFP/Getty Images]

In this handout image provided by NASA, Liz Heller and Andriel Mesznik watch the transit of Venus on June 5, 2012 in New York, New York. The Transit of Venus involves the planet Venus crossing in front of the sun. The next pair of events will not happen again until the year 2117 and 2125. (Photo by Bill Ingalls/NASA via Getty Images)
- [Bill Ingalls/AFP/Getty Images]

Venus (black dot) is silhouetted as it orbits between the Sun and the Earth during the transit of Venus seen from Bangkok on June 6, 2012. Astronomers around the world trained their telescopes on the skies to watch Venus pass in front of the Sun, a once-in-a-lifetime event that will not be seen for another 105 years.
- [PORNCHAI KITTIWONGSAKUL/AFP/Getty Images]

The planet Venus (black spot on the right) in its transit across the face of the sun is seen from Los Angeles, California on June 05, 2012. Astronomers around the world are training their telescopes on the skies to watch Venus pass in front of the Sun, a once-in-a-lifetime event that will not be seen for another 105 years.
- [JOE KLAMAR/AFP/Getty Images]

A group of students of the Astronomic Society of Engineering Faculty look at the Transit of Venus with their telescopes at the Chapultepec Castle in Mexico City on June 5, 2012.
- [ALFREDO ESTRELLA/AFP/Getty Images]

In this handout image provided by NASA, the SDO satellite captures a ultra-high definition image of the Transit of Venus across the face of the sun at on June 5, 2012 from space. The last transit was in 2004 and the next pair of events will not happen again until the year 2117 and 2125. (Photo by SDO/NASA via Getty Images)
- [NASA/AFP/Getty Images]

In this handout image provided by NASA, the SDO satellite captures a ultra-high definition image of the Transit of Venus across the face of the sun at on June 5, 2012 from space. The last transit was in 2004 and the next pair of events will not happen again until the year 2117 and 2125. (Photo by SDO/NASA via Getty Images)
- [NASA/AFP/Getty Images]

A Pakistani student watches the transit of Planet Venus across the sun using a welder's mask for eye protection while another takes a photograph using her iPhone in Lahore on June 6, 2012. Astronomers around the world trained their telescopes on the skies to watch Venus pass in front of the Sun, a once-in-a-lifetime event that will not be seen for another 105 years.
- [ARIF ALI/AFP/Getty Images]

A data capture shows Venus crossing the Sun. The 2012 Transit of Venus, on June 5-6, was the last for 105 years.
- [NASA/SDO, HMI, and AIA science teams/Courtesy]

The "black drop" effect is seen as Venus (top) begins to cross the sun's face during the transit of Venus June 5, 2012 as seen from the west side of Manhattan in New York. The optical illusion makes Venus appear to be "stuck" to the edge of the sun at the beginning and end of the transit. Astronomers around the world are training their telescopes on the skies to watch Venus pass in front of the Sun, a once-in-a-lifetime event that will not be seen for another 105 years.
- [STAN HONDA/AFP/Getty Images]

In this handout image provided by NASA, the SDO satellite captures the first image of the Transit of Venus across the face of the sun on June 5, 2012 from space. The last transit was in 2004 and the next pair of events will not happen again until the year 2117 and 2125. (Photo by SDO/NASA via Getty Images)
- [NASA/AFP/Getty Images]

In this handout image provided by NASA, the SDO satellite captures the approach of Venus before it transits across the face of the sun on June 5, 2012 from space. The Transit of Venus involves the planet Venus crossing in front of the sun. The next pair of events will not happen again until the year 2117 and 2125. (Photo by SDO/NASA via Getty Images)
- [NASA/AFP/Getty Images]

In this handout image provided by NASA, the SDO satellite captures the approach of Venus before it transits across the face of the sun on June 5, 2012 from space. The Transit of Venus involves the planet Venus crossing in front of the sun. The next pair of events will not happen again until the year 2117 and 2125. (Photo by SDO/NASA via Getty Images)
- [NASA/AFP/Getty Images]

A projected image from a telescope of Planet Venus in transit across the Sun is pictured on a screen as skygazers watch the celestial event using protective eyewear in Kolkata on June 6, 2012. Astronomers around the world trained their telescopes on the skies to watch Venus pass in front of the Sun, a once-in-a-lifetime event that will not be seen for another 105 years.
- [DIBYANGSHU SARKAR/AFP/Getty Images]