https://www.iflscience.com/space/astronomers-witness-europa-occulting-a-star-for-the-first-time/Astronomers Witness Europa Occulting A Star For The First Time
This is the first time that astronomers have observed Europa occulting a star. Only Io and Callisto, two other Jovian moons, have been previously observed creating these peculiar eclipses.
先前只發現過 IO Callisto 掩星 ,測到歐羅巴平均半徑 1,561.2 KM 赤道1,562 km 兩極比較短 1,560.4KM
Using Gaia, the team has been able to find evidence of even more occultations. Three of them have already taken place. The team was able to observe two of them (by Europa and Callisto on June 4 and June 5, 2019, respectively),
https://www.universetoday.com/142994/thanks-to-gaia-we-now-know-exactly-how-big-europa-is-1/這種罕見的事件（恆星掩星）使天文學家能夠對天體進行獨特的觀測。在歐羅巴的情況下，掩星發生在2017年，並允許天文學家更準確地測量木衛二的大小，相對於木星的位置，以及它的真實形狀。所有這一切都得益於歐空局的蓋亞天文台
