ISS and Earth Rotation

Click on picture to see it full size.

Click on picture to see it full size.

   This morning, Saturday 25 January, the International Space Station flashed its reflected sunlight in my direction as it traveled from the northwest to the southeast. at its greatest altitude it was at around 80 degrees, 10 degrees from straight. It’s path toward the southeast took it past the bright star Vega in the constellation of Lyra the Harp.
    This picture is a stacked series of several 1.3 second time exposure pictures taken as fast as I could hit shutter release. The length of each line represents the length of time exposure. The first 3 lines were before I lowered the angle of my camera bringing up into view more of the horizon. So there is an offset of the lines. As the ISS got lower in the sky the angle between the ISS and my position on Earth changed such that the streak of light got shorter.
    The arrows indicate the direction that the ISS is taking relative to the horizon, while the short line labeled Vega represents the westward direction the star Vega is following due to Earth rotation.

Caution: Objects viewed with an optical aid are further than they appear.
   Click here to go to the Qué tal in the Current Skies web site for more observing information for this month.

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