Expanding Spot on Venus Puzzles Astronomers

(PhysOrg.com) -- The expanding spot discovered on Venus last month may not have garnered as much attention as the meteor impact with Jupiter, but its cause is certainly more puzzling.

While astronomers are pretty sure that the new spot seen in Jupiter's landscape is caused by impact, there is evidence that this is not true of the spot seen on Venus. New Scientist reports on why astronomers don't think the spot of Venus was caused by a meteor:

"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, says Sanjay Limaye of the University of Wisconsin-Madison and a member of the Venus Express team."

Some of the reasons being advanced for the spot in Venus' atmosphere include:

* Volcanic eruption. (This option is considered unlikely, since the thick atmosphere would likely block most volcanic activity from being visible to us.)

* Charged particles from solar interaction with Venus' atmosphere.

* Atmospheric turbulence concentrating bright material in a confined area.

The other interesting point about the Venus bright spot is that it -- like the Jupiter "scar" -- was first noticed by an amateur astronomer. The fact that astronomy is so accessible to a wide range of people is interesting in terms of encouraging interest in the sciences.

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