ISS Passes Arcturus & Jupiter

After admiring Jupiter, Saturn, Albireo, and Mizar-Alcor, I packed up the Celestron 8 and waited a few minutes. Right on time, the ISS rose from the horizon in the northwest passing just over the thin crescent new moon. The iPad was on the roof of the car with the NightCap app running and pointed high in the southwest. A passenger plane flew west with blinking lights. Then came ISS going right-to-left just below Arcturus. It brightened as it passed over Jupiter before dimming abruptly before reaching Saturn. A lot of ground is covered traveling 5 miles per second.


3 thoughts on “ISS Passes Arcturus & Jupiter

  1. Did you notice any speed change in the ISS? When it abruptly left my sky last week, it was first going very fast, then slowed, then disappeared. I assume that is to due height/elevation angle changes (since it is not flying at a constant elevation).

    • It would be due to angle of view. From a distant vantage point it appears slower the same way a car’s headlights would appear as viewed far down the road. As it passes near you, the headlights appear moving faster. The speed hasn’t changed.

      The mean elevation varies less than 10 km from the mean of about 405 km. It is a very circular orbit. It does need a boost now and then to raise it back up. Here is an interesting chart from Heavens Above about that.

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