Imagery of the Transit of Venus from the ISS
These images were taken from the Expedition 31 crew onboard the International Space Station during the Transit of Venus event. The Transit of Venus occurred from 22:09:29 UTC June 5, 2012 to 04:49:27 UTC June 6, 2012. The next transit alignment will not occur until 2117. These images were taken from the Russian Segment Pirs Docking Compartment 1 and the U.S. Operating Segment Cupola Window 1 with its scratch pane removed. The astronauts onboard were able to capture this historic event with the use of solar filters. This transit was the first that was captured from a crewed spacecraft. The last transit occurred in 2004, but the ISS crew did not have solar filters onboard to acquire imagery. Previous to that, the last transit of Venus occurred in 1882.
The first set of six images on the left was taken using an 800mm lens with a 762nm narrow band pass filter on the Nikon D2Ss through the Russian Segment Pirs Docking Compartment 1 window. The progression of Venus across the sun is seen here from right to left. The second set of six images on the right was taken using a 1200mm lens with a neutral color solar filter on the Nikon D2Xs through Cupola Window 1 with its scratch pane removed.
The Transit of Venus also presented an opportunity to perform an overall optical test on the Cupola windows to determine the level of image degradation and blurring caused by the ISS USOS non-optical quality Scratch Panes as compared to images taken through windows where the scratch pane was removed or through Russian segment windows both of which are of optical quality. For additional information with respect to the optical test, the complete list of images in the data set, and through which window each image was taken see the TOV Catalog.
Explanation of the Transit of Venus
Observations of the Transit of Venus during the 17th, 18th, and 19th centuries allowed scientists to calculate the distance between the Earth and the Sun, while revealing the existence of an atmosphere around Venus. Since the previous pair of transits of Venus in 1874 and 1882, humans have developed the ability to view the phenomena from space—both directly from low-Earth orbit and remotely from sensors on spacecraft collecting data about the Sun.
Astronaut Don Pettit, flight engineer for International Space Station (ISS) Expedition 31, was particularly keen to take photos of the event from orbit—even bringing a solar camera filter aboard for the event. This top image, from the first half of the 2012 transit, is one of hundreds taken from the ISS Cupola, a windowed module that provides the crew with unparalleled views of both Earth and astronomical phenomena. In fact, history will record the ISS as the first orbital, crewed spacecraft from which the Transit of Venus has been observed. In addition to the dark circle of Venus visible at image upper left, several smaller sunspots are visible at image center.
The eight-image series (lower) comes from one of those solar-observing spacecraft: NASA’s Solar Dynamics Observatory (SDO). The full-disk images were captured between 21:00 Universal Time on June 5 and 06:00 UTC on June 6 by the Helioseismic and Magnetic Imager (HMI), an instrument designed to study the oscillations and magnetic field of the solar surface, or photosphere. As with Pettit’s photo, HMI reveals several sunspots near the middle of the Earth-facing side of the Sun, as well as the larger, transient disk of Venus in the upper third of the images. A movie showing the entire Transit is available for download by clicking on the link below the image or by visiting our YouTube channel. The SDO team also produced a montage of high-definition views of the Transit that you can see here.
The Transit of Venus in front of the Sun is one of only two such planetary crossings—the other being the Transit of Mercury—that are visible from Earth. While transits of Mercury occur thirteen times each century, Venus transits the Sun only twice over the same time period. (The first transit of the current pair occurred in 2004). Unless you are fortunate enough to be at locations where the transit is visible both times, this makes the Transit of Venus a true “once in a lifetime” event.
Caption by William L. Stefanov (Jacobs/ESCG at NASA-JSC) and Mike Carlowicz (Earth Observatory, GSFC).