Watch Mercury and the International Space Station Transit the Sun at the Same Time

NASA's "picture of the day" features Mercury and the ISS passing the Sun.

NASA/Thierry Legault

On Monday, we Earthlings got to ooh and aah as the scorching planet Mercury passed between the Earth and the Sun at 108,000 mph. Known as the “swiftest planet”, Mercury’s transit was a reminder that while we sit tight, all planets are in rapid and perpetual motion. Today, NASA gave a shout-out to this rare trek via its “astronomy picture of the day” — serving up a golden slice of Mercury.

The photo captures both Mercury as it crosses the Sun’s disk, as well as the movement of the International Space Station. It was taken by Thierry Legault from Philadelphia, Pennsylvania — about 52 million miles away from Mercury. Legault’s photo is a rapid-fire shot, the crossing of the ISS — moving from upper left to lower right — happened in 0.6 seconds.

The ISS naturally seems much larger than Mercury because it was a lot closer to Philadelphia than Mercury, about 279 miles.

The small, round dot in Mercury.

NASA/Thierry Legault

This shot is actually a still from a video filmed by Legault. When Mercury transits again, you could capture the moment too — if you have the right equipment and cash to spare. The equipment used to capture this moment were:

  • A IDS UI-3370 video camera with a four megapixel CMOS sensor. This is an ultra-high resolution camera, known for its powerful hardware and easily operational software design. The small camera is listed as “price upon request,” so, you know it has to be good.
  • The Takahashi FSQ-106ED refractor — a.k.a. an astrograph telescope, the necessary starter for any budding astrophotographer. If you want the best of the best, and the Takahashi is thought of as the best, you’ll have to throw down $5,150.
  • The third thing you’ll need is the Coronado SM90 H-alpha filter. Filters are necessary for astrophotography because they cut out light-pollution and any undesirable wavelengths cutting into the shot. To reduce skyglow with the Coronado, you’ll need to pay $3,999.

The crossing of the ISS in six seconds.


Legault also used these tools to capture this sweet shot of a plane crossing the sun:

A plane passes the sun.


You need this specialized equipment to have any chance of really capturing Mercury’s transit — while the transit in total took about 7.5 hours, the most visually stunning moments happen at the start and at the end, in which Mercury appears to be in the shape of a teardrop as it interacts with the edges of the sun. These transitions only happen for about three minutes, meaning your camera equipment must be able to respond quickly and with clarity.

The next time this dazzling spectacle can be seen is in 2019, so if you want your photography to be profiled by NASA, you better start saving up now.

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