https://zh.wikipedia.org/zh-tw/%E5%B0%A4%E5%88%A9%E8%A5%BF%E6%96%AF%E5%8F%B7https://en.wikipedia.org/wiki/Ulysses_(spacecraft)
https://technews.tw/2020/06/01/esa-solar-orbiter-comet-atlas-satellite-sun-c2019-y4/倫敦大學學院 Mullard 太空科學實驗室科學家 Geraint Jones 首先注意到這點。2000 年時 他曾發現尤利西斯號（Ulysses）探測器在偶然中穿越 Hyakutake 百武二號彗星（C/1996 B2） 的尾巴，
不久之後2004又穿越另一顆彗星 C/1999 T1 (McNaught–Hartley)
2007 年時穿越了第三顆彗星 C/2006 P1 (McNaught) 的尾巴
穿越 Hyakutake 百武二號彗星（C/1996 B2）
On May 1, 1996, the spacecraft unexpectedly crossed the ion tail of Comet Hyakutake (C/1996 B2), revealing the tail to be at least 3.8 AU in length
穿越另一顆彗星的尾巴 C/1999 T1 (McNaught–Hartley)
2004 when Ulysses flew through the ion tailings of C/1999 T1 (McNaught-Hartley). A coronal mass ejection carried the cometary material to Ulysses.
2007 年時穿越了第三顆彗星 C/2006 P1 (McNaught) 的尾巴。
2007 Ulysses passed through the tail of comet C/2006 P1 (McNaught). The results were surprisingly different from its pass through Hyakutake's tail, with the measured solar wind velocity dropping from approximately 700 kilometers per second (1,566,000 mph) to less than 400 kilometers per second (895,000 mph)
因此本月初，當 Geraint Jones 意識到太陽軌道飛行器將在接下來短短幾週內穿越 C/2019 Y4 彗星下游 4,400 萬公里處時，立刻向歐洲太空總署通報，科學家緊急啟動了額外任務。
