100 Stars in Mathematica: Star #004: Alycone

This week's Astronomy fun with Mathematica is Star No. 4 from Florian Freistetter's 'Universe in 100 Stars', the bright star Alcyone in the Pleiades cluster (M45) in Taurus, which Georg von Peuerbach used to improve astronomical tables in 1457.

A CTRL+= fetch from Wolfram Alpha gives us the Entity for star Alcyone. The EntityProperty 'apparent magnitude' yields 2.85. It is in fact amongst the 150 brightest stars by apparent magnitude, which you can check using:

EntityList[
 EntityClass[ "Star", {EntityProperty["Star", "ApparentMagnitude"] -> 
  TakeSmallest[150]}]
]

The EntityProperty 'constellation' for Alcyone gives us Taurus. An AstroGraphics shows the constellation lines. If you look closely you'll see that the star Elnath has constellation lines also with the neighbouring constellation Auriga.

Notice the star Elnath at the southern tip of Auriga. This star used to belong both to Auriga, where it was known as the heel of the Charioteer, and to the constellation Taurus, where it represented the tip of the Bull's northern horn. In the last century, though, the International Astronomical Union decreed that this star shall belong only to Taurus!'

Wolfram Alpha lists it correctly as only belonging to Taurus. The AstroGraph lower left shows both {Auriga, Taurus} with AstroCenter -> Elnath.

An Alpha fetch for "Pleiades" gives us the M45 STARCLUSTER entity. The EntityProperty 'alternative names' gives: {"the Pleiades", "Melotte 22", "the Seven Sisters"}

An AstroGraphics of M45 with AstroBackground -> "WhiteSky" shows the cluster nicely with the bright star Alcyone. The Wikipedia article on Pleiades has a nice shot from Palamor, but the orientation and scale is different from the AstroGraph.

Can we overlay the AstroGraphics over the Wikipedia image? Use Rasterize, RemoveBackground, ColorNegate, and some Manipulate controls for Rotate and ImageResize with ImageCompose – and a little patience – to get a convincing overlay match.

(It's probably possible to tune the AstroGraphics directly to rotate and scale it first before the other steps but the approach shown works fine.)