cusp cap

cusp cap

[′kəsp ‚kap]
(astronomy)
One of the 10 bright areas observed near one of the extremities of the illuminated portion of Venus during the crescent phase.
References in periodicals archive ?
cusp cap became notably larger on some occasions in February and March according to UV images (e.g., to Poupeau on Feb 11 [illustrated in the report in the previous Journal] and Feb 29, to Tasselli on March 2 and Ikemura on March 14), and several drawings.
cusp cap on Feb 11 on the image by Jean-Jacques Poupeau.
More rarely, owing to variations in cloud cover at the planet's poles, a cusp of the crescent may extend irregularly or even end in a "cusp cap."