Seeing Venus in a New Light
Written by Nancy Atkinson
New images taken by instruments on board ESA’s Venus Express are providing insight into the turbulent atmosphere of our neighboring planet. When viewed in beyond visible light, the ultraviolet reveals the structure of the clouds and the dynamic conditions in the atmosphere of Venus, where the infrared provides information on the temperature and altitude of the cloud tops. Most intriguing are the puzzling dark and bright zones seen on Venus in ultraviolet.
Scientists have seen equatorial areas on Venus that appear dark in ultraviolet light, and have been mystified by them. The new views with Venus Express show the cause of these different colored areas is the uneven distribution of a mysterious chemical in the atmosphere that absorbs ultraviolet light, creating the bright and dark zones. While the scientists haven't been able to identify the chemical, they have figured out the process that causes the changes in cloud types across Venus.
Professor Fred Taylor, one of the Venus Express scientists, from Oxford University said, "The features seen on Venus in ultraviolet light have been a puzzle to astronomers for nearly a century. These new images have revealed the structure in the clouds that produces them and shows how they result from complex meteorological behaviour. We can now study in much greater detail and try to understand the origin of features such as the large hurricane-like vortex over the north and south poles. Like many things on Venus, including global warming, this feature has similarities to atmospheric and environmental process on Earth, but the Venus version is much more extreme."
With data from Venus Express, scientists have learned that the equatorial areas on Venus that appear dark in ultraviolet light are regions of relatively high temperature, where intense convection brings up dark material from below. In contrast, the bright regions at mid-latitudes are areas where the temperature in the atmosphere decreases with depth.
Venus in infrared and ultraviolet. Credits: VMC ultraviolet image: ESA/MPS/DLR/IDA VIRTIS infrared image: ESA/VIRTIS/INAF-IASF/Obs. de Paris-LESIA
Observations in the infrared have been used to map the altitude of the cloud tops. Researchers were surprised to find the clouds in both the dark tropics and the bright mid-latitudes are located at about the same height of about 72 km.
Sources: ESA, Science & Technology Facilities Council
Filed under: Venus
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December 3rd, 2008 at 9:06 pm
This might explain a lot regarding the early historical records of visual observations of Venus. Venus has always shown some peculiarities in the mid- to low latitudes along the planet's terminator, of which, a few of these anomalies were at first interpreted as mountains – or at the very least, the atmosphere moving above them.
A more detail explanation of this appears in the published article in the Royal Astronomical Society of New Zealand (RASNZ), which is reproduced (with permission) at the following link. href="http://homepage.mac.com/andjames/PageVenus005.htm">Johann Schröter, William Herschel and the Mountains of Venus: Overview
Examination of this news item and Professor Taylor paper may further go to explaining the observed visual anomalies of the past. His statement; "These new images have revealed the structure in the clouds that produces them and shows how they result from complex meteorological behaviour." perhaps its origins.
December 3rd, 2008 at 9:08 pm
The reference in the reply above is;
Johann Schröter, William Herschel and the Mountains of Venus: Overview
December 7th, 2008 at 7:37 pm
Great to hear about some results from this craft. The thing is, I've never ever ever witnessed a space mission with such poor communication and updating of results to the general public. It's laughable.
They've been a bit better lately, but still not much chop.