From Dr. Tony Phillips Science at NASA
When Venus transits the sun on June 5th and 6th, an armada of spacecraft and ground-based telescopes will be on the lookout for something elusive and, until recently, unexpected: The Arc of Venus.
“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.
› View larger
The arc of Venus photographed in 2004 by Riccardo Robitschek and Giovanni Maria
Caglieris of Milan, Italy. “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.”
› View larger The arc of Venus as seen by NASA’s TRACE spacecraft in 2004. Credit: NASA/Trace/LMSAL
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.”
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Always have to question scientists that state the 900 F temperature on Venus is due to the massive amounts of CO2.
Perhaps all that “missing sink” CO2 somehow winds up on Venus.
sarc/off
“Our models and tools cannot fully explain Venus, which means we lack the tools for understanding our own planet,” points out Widemann.
——
I thought we were going to burn, the models say so!
“Earth and Venus are similar distances from the sun”
Why is this completely untrue statement so commonly spoken or written? Venus is around 30% closer to the sun and receives ~9x the energy from the sun. That’s about as dissimilar as you can get.
So there is 100x Earth’s atmosphere on Venus, making it extremely dense, but it’s not that making it hot, it’s CO2? Codswallop.
Apart from that political nod, it is all very interesting!
What a pooprly written article with some factual errors (or deliberate politcal distortions). “Similar distance”, hah. Somebody at NASA needs to read the textbook from Physics 101.
Another nice photo of venusian atmosphere:
http://eclipse.astronomie.info/transit/venus/img/antares-3kontakt-kontrast.jpg
“Earth and Venus are similar distances from the sun, …”
“Our models and tools cannot fully explain Venus, which means we lack the tools for understanding our own planet,” points out Widemann.”
If NASA’s tools currently indicate Venus and the Earth are at similar distances from the sun, perhaps the first tool that should be acquired by NASA is a brain.
George V.
“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.”
How dare he, the science is settled, our models can predict what the Earth’s atmosphere will do with utter precision. Ignore the last 15 years or so of no warming, that’s a minor glitch that will soon be ‘adjusted’ out.
JS
Just a couple of comments, here:
“…Earth and Venus are similar distances from the sun…”
WTF?
Venus, 67.2 million miles from sun.
Earth, 93 million miles from sun.
Difference of 25.8 million miles.
That’s a “similar distance”?
“…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…”
…while the Earth’s atmosphere consists mainly of water vapor – and CO2 levels are on the order of parts per million, and beneficial to life on our planet.
They’re just trying to get in the usual “CO2 causes the heat there, it must be the cause of the heat on Earth.
Closer to the heat source doesn’t matter.
“…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…”
We care about Venus – we really do. Climate Scientist Bill McKibben is trying to connect the dots now, and insisting that the CO2 levels on Venus are brought back down to the magic 350ppm.
BTW, if a planet can have that much CO2 naturally, where did it all come from?
Venus is water free and there was no dry process to convert the CO2 to O2 as happened on earth. Biological processes need water to work. Earth could have had the same dense atmosphere if it were not sequestered into the rocks as limestone.
I will argue with the super GHG cause of Venusan heat. That dense atmosphere is affected by the gravity which will add heat due to adiabatic compression. This works on Jupiter which emits far more heat than it receives and has an atmosphere of hydrogen/helium. A simple application of the combined gas laws will produce the required temperature without any GHG theory.
It would be interesting to know what Dr. Tony Phillips thinks of a recent piece –
http://wattsupwiththat.com/2010/05/08/venus-envy/
It certainly appears to have plenty of merit to it, how does the man from NASA feel about it?
I see many have already picked up on the distance thing. Is this *really* from NASA?
blogagog says:
June 5, 2012 at 4:08 am
Venus is around 30% closer to the sun and receives ~9x the energy from the sun.
No, only 2x.
blogagog says: June 5, 2012 at 4:08 am
“Earth and Venus are similar distances from the sun”
Why is this completely untrue statement so commonly spoken or written? Venus is around 30% closer to the sun and receives ~9x the energy from the sun. That’s about as dissimilar as you can get.
Only about twice the energy.
“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.”
The high temperature has little to do with CO2, and everything to do with the surface pressure. Using the adiabatic lapse rate for the Venusian atmosphere, if you ascend to where the pressure is 1 bar, earth normal, the temperature isn’t that far off from ours, especially considering the greater insolation. If our air atmosphere were at 90 bar, we’d be red hot, too.
-CLICK-
The sound of another brain turning off on hearing (yet again) the unproven claim that Venus’ surface temperature is due to a “greenhouse effect”. Wanna change that? Show me!
“we lack the tools for understanding our own planet”. Yep. That you have shown me, over and over!
Please explain why the Venus atmosphere is so much denser than the earth’s given that Venus is smaller, have less mass and lower gravitational acceleration.
ddddd
That’s to replenish the shortage of “d”s.
“A human being transported to this hellish environment would be crushed, suffocate, desiccate, and possibly ignite.”
“A human being transported to this hellish environment would be crushed, suffocated, desiccated, and possibly ignited.”
No problem, don’t mention it. You’re welcome.
Venus does have an atmosphere that is 97% CO2. However, its because the atmosphere is so thick and so much closer to the sun that causes the temperature to be so high. Not necessarily because its CO2.
henrythethird says:
June 5, 2012 at 4:35 am
“BTW, if a planet can have that much CO2 naturally, where did it all come from?”
Why Big Oil and Big Coal of course! Their slimy tentacles of death, misery, and corporate profits aren’t merely limited to Mother Gaia alone!
Venus is 2/3 the distance from the sun as the Earth. Intensity goes as the inverse of the square of the distance, so Venus receives 9/4 the solar input as the Earth. (sarc)Of course climate science has told us that the sun has no effect on temperature so it obviously must be the CO2 that makes the difference(/sarc).
Seriously, has Hanson infected EVERYTHING at NASA?
There is greater than a random chance that scientists will be compelled to use Venus as a tale of caution regarding our own CO2 output. I believe what they are hoping to discover is not basic science about Venus’ atmosphere, but biased science about ours.
I find the replies to this article very interesting and look forward to reading many more.
When asked about the ‘runaway greenhouse’ effect on Venus I have always answered that Venus is 30% closer to the sun and shoud be even hotter than it is. I put this down to the dense atmosphere reflecting much of the heat and light back into space (making Venus a very bright object in the sky). As Venus has been the way it is for a long time one would have thought a runaway greenhouse effect would have made it much, much hotter by now (even without heating due to the dense atmosphere, as I am reading above).
I am ready to be corrected on any of this, of course.
I could be wrong but I vaguely recollect that Co2 means nothing without the atmospheric pressure. Off the top of my head I think Mars is 95% Co2 and is a ‘similar’ distance to the sun (tongue in cheek).
NASA is clearly short of funding if it lacks the tools to discover that Venus and Earth are at similar distances from the Sun. If that were so we would periodically have a spectacular view of that planet looming up, not to mention the eventual spectacular collision. Venus is about 1/3 (67/93) closer to the Sun than Earth.
They also need extra funding to discover that CO2 does not cause absolutely everything including warming. A few more tools and they could check out the effect that the pressure has on the Venusian temperature. They could also investigate the water on Earth that is lacking on Venus.
This all just looks like yet another attempt to push the CAGW bandwagon out of the mud.