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Watch Space Station Bisect Moon--Repeatedly

You've seen pictures of the International Space Station (ISS), but have you ever actually seen it? If you can steady on the moon with a simple telescope, try this: an ISS transit.

As the International Stace Station (ISS) orbits overhead, occasionally its path cuts between you and the sun or you and the moon. At that moment you can discern the general shape of the giant space-borne vessel as it is silhouetted against the sun or moon. Here's a quick introduction to predicting and watching this recurring event.

The hunt to witness the ISS begins at

Fill in the empty boxes, select Calculate, and get a bunch of transits and/or close passes.

Most new telescope users can find two objects easily--the sun and the moon. Usually an inexperienced person shouldn't target the sun, which leaves small scopes aimed at the moon. I strongly encourage you to look first at lunar transits before progressing to solar transits that require additional eye safety protections. For my example going forward, however, I'm going to pursue a solar transit visible nearby. The same basic steps apply for tracking a lunar transit, with the exception of the observing equipment.

ISS transit solar 2019-12-08 Sunday

The result suggests I could watch ISS clip the edge of the moon, but it lastsonly half a second. Check the Center Line Distance to see if the close passes are close enough to chase. Or see if a swath occurs over a place you'll be visiting then.

Select Show on Map to see the swath of transit. For longest sighting of ISS bisecting the sun or moon, visit nearby swath on map at the given date and time.

Map shows swath of land from which transit is visible.

Find the new information and diagram of ISS tracking across midline of sun. Select "Recalculate For This Location" to get updated map. Zoom in and find an observing site.

Zoom in on transit path to find observing site.

Finally, get permission to set up in a parking lot.

Here's an example of an ISS transit I recorded using a Sun Funnel in 2006. Because I had been looking into the camera's viewfinder, I did not see it with my own eyes. In watching the video, you can see it zip left to right across the bottom of the projected sun.

Clear skies!

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