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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darrylb says: Is anyone else flabbergasted that it wasn’t immediately quite obvious that he was observing refracted light— and perhaps they should be looking for refraction of other frequencies of EM waves.[?]
Right! You can see the same thing in satellite photos of Earth, only it’s light blue.
“Dr.” Tony Phillips should be fired and have his Phd revoked after writing that crap. Any grammar school kid knows Venus is closer to the sun than earth.
Venus and Earth receive about the same radiation from the sun as Earth has a lower albedo, thus less radiation is reflected from the surface and clouds than Venus which receives more radiation but also reflects more due to the high sulfuric acid clouds, which are actually pretty thin less than 0.15% of the atmosphere if I recall correctly.
At work I have several gas tanks that are at twice the pressure of the atmosphere of Venus and they are at room temperature.
Venus also has almost 100 times as much deuterium as found elswhere in the solar system including earth, and it got that much because all the water on the surface evaporated and ultraviolet light from the sun hydrolyzed the water vapor into hydrogen and oxygen and the lighter isotope of hydrogen escaped into space at a higher rate than the deuterium.
thanks
“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. ”
Nearly, try again.
I don’t know if it’s my imagination or not, but I’d swear some of that article was cut and pasted off the Wikipedia page for Venus.
The distances are, indeed, very similar, relatively speaking, when measuring planet distances in AU’s. Note that things cannot “ignite” without O2. Lots of guessing going on here as there are too many processes and potential processes that could have affected how Venus became what it is. Going home to try to get some pics of this through the telescope, if it doesn’t cloud up.
I imaged the Venus arc in 2004 using a refractor telescope and webcam.
see http://arnholm.org/astro/venus/
Be very, very careful with this kind of thing. You can easily go blind if you do something wrong. It has to be imaged without a solar filter, and it is definitely not recommended for people who don’t know what thay are doing. You have been warned.
Unfortunately we are going to be rained out and not get to see it. We were going to set up all the university’s solar telescopes to view it too. However we need the rain more than the view.
Jim G: is .67AU similar to 1AU? I suppose if you round to the nearest whole number it is. The rest is good.
I can’t find it now, but whoever commented that their two atmosphere tanks were at room temperature: When those tanks were filled and the gas was compressed into them from atmospheric pressure, those tanks were HOT (provided they were filled quickly enough to not lose the heat at the same rate as it collected). They cooled to equilibrium after time. If you take an IR meter with you to a dive shop when the compressor is filling a tank, you will see the tank is warmer than the surrounding air. I hate when people try to use compressed air tanks as an argument about pressure not equaling temp. Also, your 2ATM tanks are sitting isolated from the weight of atmosphere above them and only have a meter or so of adiabatic change – which would be unmeasurable. If the whole atmosphere were 2ATM instead of 1, the lapse rate would be higher.
I also managed to image the 2004 transit… here’s a couple of shots of the 3rd contact.
http://ephemerata.wordpress.com/2009/10/28/neck-pain-and-eyestrain/#jp-carousel-342
http://ephemerata.wordpress.com/2009/10/28/neck-pain-and-eyestrain/#jp-carousel-343
Unnfortunately seeing cnditions were poor with a morning sky full of humidity, but all in all weren’t bad for a first attempt. I’m set up again tonight for contacts 1 and 2 – we’ll see how I do – trees might do me in this time – it’ll be close. No attempt at anything scientific here , judt an effort to see what I could get.
ferd berple says:
June 5, 2012 at 8:07 am
Thanks Ferd
When you take time out to add together (a) TSI (b) gravity-induced atmospheric pressure, the whole issue of atmospheric planets’ temperatures becomes obvious, simple, and finally within reach of the calculable from theory.
Again, this goes straight back to my current work on Graeff’s hard experimental evidence leading to the need for a modified restatement (NOT abolition) of the Second Law. Second article coming presently at TT, set against the background of the history and current (academic-research) state of play w.r.t. challenges to the 2LoT. Nothing velikovsky-like, just the familiar workings of straightforward science.
IOW I may, like Monckton, lack formal qualifications, but that does not preclude good scientific attitude, reasonable scientific awareness, the ability to study the necessaries, or the ability to listen to relevant evidence and modify my views accordingly.
As seen from 128 Nemesis, both the Earth and Venus will together transit the Sun. Would the people over there on Nemesis also see an ‘arc of the Earth’?
Why do planets spin?: (Warning: You will be committing a SIN against the “Consensus Church” if you see the following) 🙂
My guess is that this type of anti-science post is designed to question the scientific validity of this website – by implying that sceptics believe the earth spins because its a magnet.
Yes, that you have a video of a simple electric motor – powered by the battery (the copper wire contacts the battery on the negative terminal, the the magnets contact the battery on the positive terminal, and the current flowing creates a magnetic field that in the wire that pushes the wire around the magnet at the base of the battery. The trick is that the contact at the base of the battery is pulled first one direction, then the other while the wire is spinning so that the magnetic field in the wire is always kept in opposition to the magnetic field of the magnets that the battery is sitting on.
You can’t possibly conflate the magentic field of the earth with the current flow from the battery though. There is simply no comparison. Sure, the earth has a magentic field, but for the motor to work, it has to have two opposing magnetic fields that always work against each other. Where is the second field? Even if there was a second field, it would have to be alternated to make a working motor out of it. Either the earth’s poles would need to flip every 12 hours, or the magnetic force its working against would have to flip every 12 hours. Even if you said that magnetic field came from the sun, I would think it would be more likely to shrink earth’s orbit than to induce spin.
OK if it turns out that the temperature of Venus is found to be far cooler than expected, how many NASA staff will be reading up on Immanuel Velikovsky?
Also if there are obvious gravitational anomalies with an increase in earthquakes, volcanic activity and the odd extra tsunami over the next year, how many will be reading up on Maurice Allais?
Here is California the full disk of Venus is now visible against the sun.
It’s cloudy and rainy here. Thru this WUWT link:
http://wattsupwiththat.com/reference-pages/solar/
I can see Venus “blocking” the sun in this image:
http://sdo.gsfc.nasa.gov/assets/img/latest/latest_1024_0193.jpg
Of course, it will be refreshed before anybody reads this. Anybody doing any jpg captures?
Another WUWT lead:
http://venustransit.gsfc.nasa.gov/data/kiosk/dataset/Venus_AIA96s_171Track/phase/track
At 7:28 AM, Wednesday 6 June in Japan:
http://www.yomiuri.co.jp/zoom/20120606-OYT9I00132.htm
Does anyone have a comment on what I found most interesting?
That is– using earth days as a unit of measure, the atmosphere spins around Venus in
just four days. It seems that much could be concluded from that fact.
(not that I have anything to offer at this point)
Here’s a quickie, just after second contact. I managed not to perfect focus so its a little off. I got a few more shots off before the trees swallowed it. ETX90 and a 1000 Oaks filter into my ol’ Nikon 950… Same stuff I used 8 years ago…. eek! Didn’t have much time this year to set something more elaborate.
http://ephemerata.ca/uploads/2012Venustransit2nd.jpg
Lucy Skywalker says:
June 5, 2012 at 2:25 pm
ferd berple says:
June 5, 2012 at 8:07 am
Thanks Ferd
When you take time out to add together (a) TSI (b) gravity-induced atmospheric pressure, the whole issue of atmospheric planets’ temperatures becomes obvious, simple, and finally within reach of the calculable from theory.
================
It all became obvious to me when I imagined a single “average” gas molecule.
Now what happens when this molecule impacts the surface? It rebounds in a perfectly elastic fashion, on average gaining energy or losing energy from the surface, based on the relative kinetic energy (temperature) of the gas molecule and the surface molecule.
This molecule then travels upwards from the surface at a velocity determined by its kinetic energy (temperature). However, a strange thing happens. Unless it collides with another molecule, the gravity of the earth slows the velocity of the gas molecule as it travels upwards, decreasing its kinetic energy (temperature).
Now the gas molecule begins to fall back towards the earth. As it falls it gains speed (unless it collides with another molecule) and as it gains speed it gains kinetic energy and thus its temperature increases, until it contacts the surface and the process begins again.
Add up the number of molecules, times their kinetic energy, divide by volume and that gives you the temperature you see on a thermometer. Increase the number of molecules per unit of volume, while leaving the kinetic energy the same, you increase the temperature.
Blogagog,
“Venus is around 30% closer to the sun and receives ~9x the energy from the sun.”
It would have to be 66% closer to receive 9 times the insolation. If it were 30% closer it would get only double the energy per area.
For you who do not think that the CO2 on Venus is responsible for it’s higher temperatures you don’t seem to realize that not only is the Venusian ATM 100 X denser it is also mostly CO2. So the amount of CO2 is close to a quarter million times as much as on earth.
“Now scientists have discovered that magnetic reconnection also happens on Venus, a planet with no intrinsic magnetic field. The finding, reported today in Science1, suggests that magnetic reconnection may generate auroras on Venus, and could have contributed to the loss of a thick, water-rich atmosphere that scientists believe surrounded the planet during its early history, some 4 billion years ago.”
…
“Just as the solar wind erodes a comet’s tail, it may have also gradually detached molecules, such as water, from Venus’s atmosphere.”
http://www.nature.com/news/magnetic-storms-spotted-on-venus-1.10397
Haven’t we all been told that Venus lost its water because of a runaway greenhouse? I never believed it, since greenhouses can not run.
I don’t know if it’s the same Dr Tony Phillips, but there is a Dr Tony Phillips who does spaceweather.com.
What happened to the mysteriious arc? Looks like no one saw it this time around.
You can order 20×30″ posters of the Transit of Venus in ultra high resolution here
See also the WUWT sidebar.
several howlers in the article….NASA is in bad shape…by the way…how do they know the whole atmosphere spins around the planet in four days?…even if you could see past the opaque sulfuric acid clouds…it would seem logical for different layers to move at different speeds