NASAさんのインスタグラム写真 - (NASAInstagram)「Though NASA's Parker Solar Probe's focus is the Sun, the spacecraft captured stunning views of Venus during its close flyby of the planet in July 2020. When flying past Venus in July 2020, Parker Solar Probe’s WISPR instrument, short for Wide-field Imager for Parker Solar Probe, detected a bright rim around the edge of the planet that may be nightglow — light emitted by oxygen atoms high in the atmosphere that recombine into molecules in the nightside. The prominent dark feature in the center of the image is Aphrodite Terra, the largest highland region on the Venusian surface. Bright streaks in WISPR, such as the ones seen here, are typically caused by a combination of charged particles — called cosmic rays — sunlight reflected by grains of space dust, and particles of material expelled from the spacecraft’s structures after impact with those dust grains. The number of streaks varies along the orbit or when the spacecraft is traveling at different speeds, and scientists are still in discussion about the specific origins of the streaks here. The dark spot appearing on the lower portion of Venus is an artifact from the WISPR instrument. Some of the features seen by scientists are labeled in the annotated image. The dark spot appearing on the lower portion of Venus is an artifact from the WISPR instrument. Read more at the link in our bio. Credits: NASA/Johns Hopkins APL/Naval Research Laboratory/Guillermo Stenborg and Brendan Gallagher」2月25日 5時57分