Multiple telescopes will analyze this peculiar phenomenon

Jun 5, 2012 08:10 GMT  ·  By
Three photos from the Arc of Venus observed during the planet's 2004 transit by amateur astronomer near Toulouse, France
   Three photos from the Arc of Venus observed during the planet's 2004 transit by amateur astronomer near Toulouse, France

During the last Venusian transit of the Sun, in 2004, astronomers photographed a mysterious arc of light around our neighboring world. Though theories to explain its origin exist, scientists now plan to use multiple spacecraft and ground telescopes to observe the phenomenon yet again.

As evidenced in the image to the left, Venus is surrounded by an arc of light as it comes up from behind the Sun. When it was first detected, this arc puzzled experts, since they had no idea something like this was possible.

In the 8 years since, astronomers have explained the event saying that it was caused by light refracted through Venus' thick atmosphere in unusual patterns, temporarily turning it into a “ring of fire.” During the new transit, which begins today, telescopes will analyze this issue in more detail.

According to physicists, the sunlight bounces off the top of Venusian clouds, creating this interesting effect. At the same time, analyzing it could reveal a wealth of data on the planet, including some that may shed light on some of its deepest mysteries.

“I was flabbergasted when I first saw it during the 2004 transit. A bright, glowing rim appeared around the edge of Venus soon after it began to move into the Sun,” Williams College astronomy professor Jay Pasachoff says.

He explains that studying the light arc could help us understand the similarities and differences between Earth and Venus. The second planet from the Sun is the closest Earth-analog, and would most likely be able to support life, if its atmosphere weren’t plagued by a runaway global warming effect.

“We do not understand why our sister planet's atmosphere evolved to be so different than Earth's,” Observatoire de Paris planetary scientist Thomas Widemann adds. He says that the two planets share similar positions, chemical makeups, and are roughly the same size.

However, the Venusian atmosphere is 100 times more massive than ours, and contains mostly carbon dioxide. Ours is primarily made up of nitrogen and oxygen. A human teleported to Venus will be crushed, suffocated, desiccated, and maybe set ablaze, at roughly the same time.

“Our models and tools cannot fully explain Venus, which means we lack the tools for understanding our own planet. Caring about Venus is caring about ourselves,” Widemann explains, quoted by NASA.

Since the Arc of Venus reveals the planet's mid-atmosphere, it may be possible to use this information to explain super-rotation, a phenomenon that sees the planet's atmosphere spin around its surface once every four days. By comparison, our neighboring world has a spin period of 243 days.