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@b0yle @SpaceX @Marco_Langbroek @Astroguyz @Alex_Parker @danielcincu @elonmusk @mcjamez @TrevorMahlmann Conducted a simple analysis on a complete Starlink Phase 1 constellation. 1584 satellites: 24 planes with 66 satellites each. 53° inclination; 550 km altitude. I assumed the relative phasing as I have no direct information. 1/12
@b0yle @SpaceX @Marco_Langbroek @Astroguyz @Alex_Parker @danielcincu @elonmusk @mcjamez @TrevorMahlmann I do not know the absolute magnitude of the Starlink satellites. I’m simply looking at lighting conditions. Some existing satellites are naked eye visible. Others are much dimmer and require binoculars. Others like old Iridiums flare. 2/12
@b0yle @SpaceX @Marco_Langbroek @Astroguyz @Alex_Parker @danielcincu @elonmusk @mcjamez @TrevorMahlmann I ran an analysis to determine number of satellites visible under the following conditions: Satellite in full sunlight. Observer with sun -6° below horizon (end of civil twilight). I also limited to satellites visible at least 5° above horizon. 3/12
@b0yle @SpaceX @Marco_Langbroek @Astroguyz @Alex_Parker @danielcincu @elonmusk @mcjamez @TrevorMahlmann I did not try to account for reflection angle (sun-satellite-observer angle). This can significantly impact the brightness of the satellite, especially any flaring. Satellite attitude and surfaces will also affect the brightness. 4/12
@b0yle @SpaceX @Marco_Langbroek @Astroguyz @Alex_Parker @danielcincu @elonmusk @mcjamez @TrevorMahlmann Analysis was for end of May at 38° latitude. This roughly equates to latitude of San Francisco, Washington, DC, Madrid, Istanbul, Seoul. I ran the analysis for 3 days, which should provide a decent average for a constellation of this size. 5/12
@b0yle @SpaceX @Marco_Langbroek @Astroguyz @Alex_Parker @danielcincu @elonmusk @mcjamez @TrevorMahlmann For satellites in a quasi-terminator orbit (much like just launched satellites) observer may potentially see a given satellite up to 5 times in one night. Satellites may stay in sunlight for up to 5 continuous days before orbit precesses enough to restart eclipses. 6/12
@b0yle @SpaceX @Marco_Langbroek @Astroguyz @Alex_Parker @danielcincu @elonmusk @mcjamez @TrevorMahlmann Contrary to what @elonmusk for satellites in a quasi-terminator orbit the satellite NEVER goes into the earth shadow, and can continue being visible at any point during the night when it is flying over the observer. 7/12
@b0yle @SpaceX @Marco_Langbroek @Astroguyz @Alex_Parker @danielcincu @elonmusk @mcjamez @TrevorMahlmann Satellites in other planes (besides the quasi-terminator) may only be visible once during the night or not at all for any given night. 8/12
@b0yle @SpaceX @Marco_Langbroek @Astroguyz @Alex_Parker @danielcincu @elonmusk @mcjamez @TrevorMahlmann At the start and end of the night about 50 satellites are simultaneously visible that meet the criteria listed above. The satellites are distributed primarily in the direction that the sun set (in the evening) or will rise (in the morning). 9/12
@b0yle @SpaceX @Marco_Langbroek @Astroguyz @Alex_Parker @danielcincu @elonmusk @mcjamez @TrevorMahlmann At midnight 18 satellites are still visible. The visible satellites are distributed north of the observer. Again, sorry @elonmusk, you will still be able to see some of your satellites at midnight. 10/12
@b0yle @SpaceX @Marco_Langbroek @Astroguyz @Alex_Parker @danielcincu @elonmusk @mcjamez @TrevorMahlmann As others have mentioned, there is already a lot of satellites and junk up there. The impact of Starlink satellites will depend on just how bright they are. Initial reports by @Marco_Langbroek was that they could be seen naked eye, but latest passes required binoculars. 11/12
@b0yle @SpaceX @Marco_Langbroek @Astroguyz @Alex_Parker @danielcincu @elonmusk @mcjamez @TrevorMahlmann As a reminder, this analysis is just phase 1 of Starlink. Does not include later Starlinks, or satellites by @OneWeb, @Telesat, @amazon, or many others. 12/12
