In the sky tonight: two spaceships

The Space Shuttle Discovery is set to depart from the International Space Station this afternoon, with undocking scheduled for 3:26 PM EDT and final separation at 5:09 PM EDT. Then the fun begins.

All across the contiguous 48 states, assuming the sky is clear (or at least clear enough to see Venus — thin, wispy clouds are OK), there will be opportunities tonight to see the spacecrafts fly overhead in tandem, in some cases multiple times. According to this article, the Shuttle will be leading, the ISS trailing.

As I’ve written before, it is very cool to see these “two distinct, bright dots, moving briskly across the evening sky in tandem — two unmistakable beacons of the human presence in space.” Unlike some of my skywatching tips, this one isn’t just for total nerds:

Trust me: even if you’re not into dorky stuff like Iridium flares, this is well worth a trip outside at the proper time, if the sky is clear. (And you don’t need to be in a low-light-pollution location to see them. They’re very bright. So long as you’re not standing, like, directly under a streetlight or something, you should be able to see them, even from downtown in a major city. Basically, if you can see Venus, you can see the ISS and Shuttle.)

Less than three hours after final separation, the pair of spacecrafts should be visible all along the East Coast, between 7:40 PM and 7:48 PM EDT, depending on the viewer’s location (further south = earlier).

Roughly 90 minutes after that, another double flyover will be visible all across the eastern two-thirds of the country, between 9:10 PM and 9:20 PM EDT (8:10-8:20 CDT). Again, further south and west = earlier.

After another 90 minutes go by, yet another double flyover will occur, this time visible from the entire western U.S., including right here in Denver, from 8:44 PM to 8:51 PM MDT (7:44-7:51 PDT). Again, the further south and west you are, the earlier in that time range the flyover will be.

Finally, after still another 90 minutes, the Pacific Northwest (which should be able to just barely see the previous flyover, close to the horizon) will get its own flyover, looking west over the Pacific at 9:20-9:23 PM PDT.

So basically, almost everyone in the 48 contiguous states should have a chance — if the sky is clear, of course — to see the ISS and the Space Shuttle flying together tonight. The four viewing opportunities I’ve mentioned are, respectively, roughly 2 1/2 hours after final separation, 4 after afterward, 5 1/2 hours afterward, and 7 hours afterward. In all cases, the Shuttle & ISS should be quite close together in the sky, and a stunning sight to behold.

If it’s cloudy tonight, never fear: there will be more viewing opportunities tomorrow. But of course, the ships will be somewhat further apart by then. Tonight is definitely the best night to try and see them, if you can.

To find out the exact time of your local flyover, and where in the sky you should look, you can use the Simple Satellite Tracker — just enter your ZIP code, and look for “ISS-Discovery” on tonight’s list of flybys.

Or, for more detailed information, enter your location here and click “Search.” (If you’re outside of the U.S., you’ll first need to select your country here.) Then pick your location from the resulting list, and then click under “Satellites” where it says “10 day predictions for: ISS.”