No planet, from Earth’s perspective, gets closer or appears brighter than Venus.
An infrared view of Venus’s night side, by the Akatsuki spacecraft. The features revealed here correspond to temperature variations across various layers and properties of the Venusian clouds. (
Venus’s phases helped validate the heliocentric model.
Over time, even from Earth, Venus can be seen to progress from small and full to large and crescent-like as seen from Earth. Only if Venus and Earth mutually orbit the Sun, with Earth as an outer planet and Venus as an inner one, is this perspective plausible without resorting to some sort of special pleading argument, where different rules apply to Venus than to Earth. (
: Christopher Illidge)
And yet, the Venusian surface remained unseen until the 1970s.
As seen by the ESA’s Venus Express mission, the cloudy features on Venus are prominent and spectacular. However, it’s what’s beneath the clouds that many scientists are interested in: a view that, until recently, it was thought to be impossible to obtain with visible light from orbit. (
: ESA/MPS, Katlenburg-Lindau, Germany/Venus Express)
Even from orbit,
clouds completely enshroud Venus.
This view of Venus comes courtesy of Mariner 10 data, with the right-side image showing the further details revealed by additional image processing. The clouds shown here are located approximately 60 kilometers (~37 miles) above the surface of Venus, where Earth-like pressures and temperatures exist. (Credit: NASA/JPL-Caltech)
The thick Venusian atmosphere possesses a multi-tiered haze over 20 kilometers (12 miles) thick.
Multiple layers of clouds on Venus are responsible for different signatures in different wavelength bands, but all show a consistent picture of a “hothouse” planet dominated by a runaway greenhouse effect. (
: Venus Express/Planetary Science Group)
Many have speculated about
the possibility of cloud-based life on Venus.
A hypothesized pathway, involving microorganisms, that could produce the necessary amount of phosphine in the Venusian atmosphere. This involves a healthy dose of speculation, and should be treated accordingly. If phosphine turns out not to be present, this pathway evaporates as a viable life-on-Venus scenario. (
: S. Seager et al., Astrobiology, 2021)
The conditions, some ~60 kilometers (~37 miles) up, are surprisingly Earth-friendly.
The proposed High Altitude Venus Operational Concept (HAVOC) mission would have search for either past or present life in the upper atmosphere of Venus, where conditions are surprisingly similar to those found in the environment right at Earth’s surface. This task will fall to other future missions, like DAVINCI and VERITAS, instead. (
: NASA Langley)
Generations ago, many
speculated about colonizing Venus, anticipating continuous rain.
Some speculated even more wildly,
However, the extreme temperatures effectively render Venus’s surface inhospitable.
The surface of Venus, as reconstructed with the radar mapping conducted jointly by NASA’s Magellan mission and the Earth-based Arecibo telescope, which was used to fill in the areas that Magellan could not image. (
A series of Soviet landers
revealed the Venusian surface for the first time.
The first-ever image from the surface of Venus was taken by the Venera 9 lander, which touched down in 1975. (
: Russian Academy of Sciences / Ted Stryk)
With temperatures reaching ~900 °F, even lead melts rapidly.
This “footprint” view of the surface of Venus was taken with the Venera 13 lander: the second-to-last lander launched by the Soviet Union that would touch down on Venus and image it. (
: USSR Academy of Sciences/Don Mitchell/Brown University)
multiple successful landings, the result was always the same.
The surface of Venus, as seen by one of the Soviet Union’s old Venera landers (most likely Venera 14): the only set of spacecraft to ever successfully land and transmit data from that world. The series of Venera landers survived for between 39 minutes to just over 2 hours; no longer. (
: Venera landers/USSR)
In under 3 hours,
the landers permanently ceased to function.
Thanks to mapping conducted with radar technology, such as this full-planet view taken by Arecibo over time, the surface of Venus has been mapped. Even though the clouds are largely opaque, we do, in fact, know what the surface looks like. (Credit: PHL @ UPR Arecibo, NASA)
However, longer wavelengths penetrate Venus’s cloudy haze.
This radar map of one of Venus’s hemispheres was constructed based on data from NASA’s Magellan mission. Only long wavelengths of light can penetrate Venus’s clouds and see down to the surface from outside of Venus’s environment. (
NASA’s Magellan mission successfully mapped Venus’s surface from orbit.
When NASA’s Magellan mission completed, it had collected over 1200 Gigabits of data in its observations of Venus: more than all other planetary science missions combined to that point. This view of its other hemisphere shows the remainder of the Venusian surface. Magellan achieved 98% total coverage in all. (
Subsequently, Venus had been thought to be
eternally, fully clouded over.
This composite image of Venus’s illuminated day side (left, from Venus Express) and dark night side (right, from AKATSUKI) shows the “superrotation” of its atmosphere and the clouds within it, which travel faster than the planet rotates. Superrotation is more uniform on the day side but becomes irregular and less predictable on the night side. (
: JAXA/ESA/J. Peralta; JAXA/R. Hueso, UPV/EHU)
But recent results
from NASA’s Parker Solar Probe show otherwise.
As Parker Solar Probe flew by Venus on its fourth flyby, its WISPR instrument captured these images, strung into a video, which show the nightside surface of the planet. (
optical images of Venus’s night side match the long-wavelength Magellan data.
The WISPR data from the Parker Solar Probe, in monochrome, clearly matches the surface features seen by the significantly longer-than-optical wavelengths of the orbiter Magellan, shown in assigned color. (
: NASA/APL/NRL (left), Magellan Team/JPL/USGS (right))
clouds really do part, rendering Venus’s surface visible, after all.
Mostly Mute Monday tells an astronomical story in images, visuals, and no more than 200 words. Talk less; smile more.