The Venus Transit
by Cody Matz
June 05, 2012 8:04 PM
A spectacular sight seen across the U.S. Tuesday evening as Venus crosses in front of the sun to get a once in a lifetime glimpse at what the planet may actually look like. Below are several images taken from different cameras and telescopes from Hawaii to the shores of Georgia. These images appear in different color depending on the type of camera/telescope and their filters. Notice in at least one of them, you can see the sunspots as well as the perfect circle of Venus. For more information on what this all means for the science community, check out the previous blog, which is below the pictures. Enjoy!!
*****Additional Information on the Transit is in the article below*****
The planet Venus, which is just one of two planets closer to the sun then earth, will be orbiting between the earth and the sun Tuesday which will give us a spectacular show… if you know how to view it. When Venus passes directly between the earth and the sun, we will see it as a small dot gliding slowly across the face of the sun. As anticlimactic as this may seam, it’s actually a really big deal in celestial terms. Historically speaking, this rare alignment is how humans first measured the size of our solar system. This spectacle is also the main way we find planets in distant solar systems. If you want to view the transit, you will likely need some preparation like you did with the solar eclipse because you can’t just stare at the sun. Even if you did, compared to the moon in our sky, Venus is just a pin dot that will block out next to no sunlight. So, you will need some tools to help your viewing. Check out this website for 6 different ways you can watch with your own eyes… click here. But if you don’t wanna deal with the hassle of setting up your own equipment then you can watch a world wide webcast of the event taking place on this website… click here. Still aren’t convinced?? Well then here’s another reason; you wont have another chance to see this…… ever!! The next time this will occur will be in December of 2117… more then 100 years from now. This whole event kicks off just after 5PM CDT and will last through sunset. The best time for viewing will likely be between 7 and 8PM when Venus is midway through the transit. You can see the path that Venus will take in the picture on your left.
Now, when Venus transits the sun, a pretty spectacular event happens which has been named The Arc of Venus. This isn’t something you can see without a telescope or special camera, but it is amazing nonetheless. For the details on this event, an article from NASA:
"I was flabbergasted when I first saw it during the 2004 transit," recalls astronomy professor Jay Pasachoff of Williams College. "A bright, glowing rim appeared around the edge of Venus soon after it began to move into the sun."
For a brief instant, the planet had turned into a "ring of fire."
Researchers now understand what happened. Backlit by the sun, Venus's atmosphere refracted sunlight passing through layers of air above the planet's cloudtops, creating an arc of light that was visible in backyard telescopes and spacecraft alike.
It turns out, researchers can learn a lot about Venus by observing the arc. Indeed, it touches on some of the deepest mysteries of the second planet.
"We do not understand why our sister planet's atmosphere evolved to be so different than Earth's," explains planetary scientist Thomas Widemann of the Observatoire de Paris.
Earth and Venus are similar distances from the sun, are made of the same basic materials, and are almost perfect twins in terms of size. Yet the two planets are wrapped in stunningly dissimilar blankets of air.
Venus's atmosphere is almost 100 times more massive than Earth's and consists mainly of CO2, a greenhouse gas that raises the surface temperature to almost 900°F. Clouds of sulfuric acid tower 14 miles high and whip around the planet as fast as 220 mph. A human being transported to this hellish environment would be crushed, suffocate, desiccate, and possibly ignite.
For the most part, planetary scientists have no idea how Venus turned out this way.
"Our models and tools cannot fully explain Venus, which means we lack the tools for understanding our own planet," points out Widemann. "Caring about Venus is caring about ourselves."
One of the biggest mysteries of Venus is super-rotation. The whole atmosphere circles the planet in just four Earth days, much faster than the planet's spin period of 243 days. "The dynamics of super-rotation are still a puzzle despite a wealth of data from landmark missions such as NASA's Pioneer Venus, Russia's Venera and VEGA missions, NASA's Magellan and more recently ESA's Venus Express."
This is where the Arc of Venus comes in. The brightness of the arc reveals the temperature and density structure of Venus's middle atmosphere, or "mesosphere," where the sunlight is refracted. According to some models, the mesosphere is key to the physics of super-rotation. By analyzing the lightcurve of the arc, researchers can figure out the temperature and density of this critical layer from pole to pole.
When the arc appeared in 2004, the apparition took astronomers by surprise; as a result, their observations were not optimized to capture and analyze the fast-changing ring of light.
This time, however, they are ready. Together, Pasachoff and Widemann have organized a worldwide effort to monitor the phenomenon on June 5th, 2012. "We're going to observe the arc using 9 coronagraphs spaced around the world," says Pasachoff. "Observing sites include Haleakala, Big Bear, and Sacramento Peak. Japan's Hinode spacecraft and NASA's Solar Dynamics Observatory will also be gathering data."
Pasachoff has some advice for amateur astronomers who wish to observe the arc. "The best times to look are ingress and egress--that is, when the disk of Venus is entering and exiting the sun. Ingress is between 22:09 and 22:27 UT on June 5th; egress occurs between 04:32 and 04:50 UT. Be sure your telescope is safely filtered. Both white light and H-alpha filters might possibly show the arc."