Known for his exquisite imagery of planets, stars, satellites and anything in space in general, photographer Thierry Legault has yet again snapped an amazing image of the International Space Station transiting the Sun.
The image above is a composite of several video frames captured on August 21 from the area of Paris, France. Legault has used an array of imagery devices to come up with these pristine shots of the ISS transiting the Sun. According to the photographer he used Takahashi FSQ-106, Coronado SM90 DS, and Basler acA1920-155um for his work.
One of the things about capturing image of the ISS as it transits the moon or the Sun is the perfection as far as timing is concerned. Further, other factors such as the tilt and timing of the orbit of the ISS, and Earth’s rotation are other factors that dictate whether the attempt to snap the ISS while it transits other celestial bodies will be a success or not.
ISS transits the Sun such that we can see it from the ground (as in the photograph) at very specific locations and time. Though there are a few software that helps keep a tab on these timings and locations, its not as easy as just clicking a few buttons here and there.
Legault prior work involves images of the ISS as it transits the Sun during a solar eclipse, Northern Lights (auroras) filmed in real-time from Norway, Indonesian volcanoes, SpaceX Dragon over Paris among other photos.
For this particular image, Legault has used a special filter (called an H-alpha filter) so that only a very narrow slice of colour can pass through. Because the light emitted from the Sun is so fierce, a photograph without the filter would be basically a smug of bright light and nothing else. Only allowing this particular wavelength of light through is what does the trick of delivering astonishing surface features on the Sun as well as anything transiting it.