London, July 30 (ANI): Astronomers have detected a new mysterious bright spot on the planet Venus, which might have been caused by volcanic activity, turbulence in the planet's atmosphere, or charged particles from the sun.
According to a report in New Scientist, amateur astronomer Frank Melillo of Holtsville, New York, first spotted the new feature, which is brighter than its surroundings at ultraviolet wavelengths, on the planet's southern hemisphere on July 19.
The Venus spot was confirmed by other observers, and images from Europe's Venus Express, the only spacecraft in orbit around the planet, later revealed that the spot had appeared at least four days before Melillo saw it.
Observations show that the spot had already spread out somewhat by the end of last week, and astronomers are awaiting more recent observations from Venus Express.
The spot is bright at ultraviolet wavelengths, which may argue against a meteoroid impact as a cause.
That's because rocky bodies, with the exception of objects very rich in water ice, should cause an impact site to darken at ultraviolet wavelengths as it fills with debris that absorbs such light, according to Sanjay Limaye of the University of Wisconsin-Madison and a member of the Venus Express team.
Another possibility is that a gust of charged particles from the sun could have created the glow by energizing a patch of the upper atmosphere.
Alternatively, waves in the atmosphere, which trigger turbulence and are thought to carry material up and down, could have concentrated bright material to create the spot.
A volcanic eruption is another suspect.
Venus boasts the most volcanoes of any planet in the solar system, and nearly 90 percent of its surface is covered by basaltic lava flows, although no 'smoking gun' has yet been found for current volcanic activity.
But, an eruption would have had to be very powerful to punch through a dense layer in Venus's atmosphere to create the spot some 65 to 70 kilometres above the planet's surface.
"It's fair to say something unusual happened on Venus. Unfortunately, we don't know what happened," Limaye told New Scientist.
Two spectrometers on board Venus Express might help reveal the culprit.
One directly measures the spectrum of light emanating from the planet, while the other can measure trace constituents in the atmosphere by measuring how gases there absorb sunlight.
These instruments could reveal changes in the size distribution of particles in the atmosphere and higher concentrations of molecules, such as sulphur dioxide, that could suggest a volcanic eruption. (ANI)