# Get Ready for the 2019 Mercury Transit of the Sun

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 On November 11, 2019, the planet Mercury will transit across the face of the Sun. If you have a suitably designed telescope or other observing apparatus for observing the Sun (check with your local astronomy club), you can watch a tiny black dot move across the face of the Sun. I used Wolfram Language to simulate what you might see.The entire event will last about 5.5 hours: start = DateObject[{2019, 11, 11, 7, 35, 27}, TimeZone -> -5]; end = DateObject[{2019, 11, 11, 13, 4, 14}, TimeZone -> -5]; dd = DateDifference[start, end]; This corresponds to a little less than 5.5 hours. In[4]:= UnitConvert[dd, "Hours"] Out[4]= Quantity[5.47972, "Hours"] The angular radius of the Sun and Mercury are needed to have a realistic simulation ("AngularRadiusFromEarth", and "AngularDiameterFromEarth" for Star entities coming soon). sunradius = .5383/2; mercuryradius = QuantityMagnitude[ Entity["Planet", "Mercury"][ Dated["AngularDiameterFromEarth", start]]/2, "AngularDegrees"]; Next I define a list of dates, from the start to end of the event, at 5 minute increments: dates = DateRange[start, end, Quantity[5, "Minutes"]]; Both the Sun and Mercury move during the course of the event so we need lists of their positions as time progresses. sunpos = {-1, 1}*# & /@ QuantityMagnitude[ SunPosition[dates, CelestialSystem -> "Equatorial"], "AngularDegrees"]["Values"]; mercpos = {-1, 1}*# & /@ QuantityMagnitude[ Transpose[{Entity["Planet", "Mercury"][ Dated["RightAscension", #] & /@ dates], Entity["Planet", "Mercury"][ Dated["Declination", #] & /@ dates]}], "AngularDegrees"]; Finally, we can plot the position of both objects using the following showing Mercury advancing across the Sun's visible disk. Graphics[{Yellow, Disk[{0, 0}, sunradius], Black, Disk[#, mercuryradius] & /@ (mercpos - sunpos)}, ImageSize -> 600, Frame -> True, FrameTicks -> None, FrameLabel -> {"S", "E", "N", "W"}, Background -> Black, LabelStyle -> {White}] This will make the graphics shown at the top of the post.