Astronomers have recently speculated that our nearest neighbor, Venus, may have been he first habitable planet in the Solar System — “a place where life was just as likely to arise as it was on Earth,” says Darby Dyar, a planetary scientist at Mount Holyoke College with NASA’s Solar System Exploration team.
Coming off its fifth encounter with the Sun in 2020, the NASA’s Parker Solar Probe headed toward Venus, where on July 11, the spacecraft performed its first outbound flyby of Venus, passing approximately 516 miles above the surface as it curved around the planet passing through the planet’s weird “tail” –formed by gas particles in the planet’s atmosphere becoming charged ions, at which point they can escape Venus’ gravity and escape into outer space.
Wide-field Imager Detects Nightglow
On its flyby the Probe’s WISPR instrument, short for Wide-field Imager, detected a bright rim around the edge of the planet that may be nightglow — which occurs at the invisible wavelengths of infrared emitted by oxygen atoms high in the atmosphere that recombine into molecules in the nightside. This eerie infrared light from nitric oxide has revealed that the atmosphere of Earth’s nearest neighbor is a volatile environment of high winds and turbulence.
In 2009, the ESA’s Venus Express spacecraft observed an eerie glow with the Visible and Infrared Thermal Imaging Spectrometer (VIRTIS) instrument, which can see infrared, made two unambiguous detections of the so-called nightglow.
“The nightglow can give us a lot of information,” said Antonio García Muñoz, who was at the Australian National University when the 2009 research was carried out; he is now located at the Instituto de Astrofísica de Canarias, Tenerife, Spain. “It can provide details about the temperature, wind direction, composition and chemistry of an atmosphere.”
The prominent dark feature in the center of the image at the top of the page is the alluringly named Aphrodite Terra, a buckled and fractured highland region of extensive lava flows.. Bright streaks in WISPR, such as the ones shown above, 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.
Image credit: NASA/Johns Hopkins APL/Naval Research Laboratory/Guillermo Stenborg and Brendan Gallagher