EntityQ1367380· pop 15· linked from 18 articlesBlack drop effectSign in to saveoptical phenomenon during a transit of Venus and MercuryConnectionsSunConceptVenusEntityMercuryEntityJames CookEntityastronomical unitEntityFriedrich BesselEntitybibcodeEntityQ118398EntityRoyal ObservatoryEntitytransit of VenusEntityastronomical transitEntitymicrometerEntityFriedrich Wilhelm ArgelanderEntitytransit of MercuryEntityTorbern BergmanEntitylimb darkeningEntityone-drop ruleEntityCharles GreenEntityCategoriesAstronomical transitsOptical phenomena