Venus and Mercury Blasted by Recent Solar Storms

by Nancy Atkinson on August 18, 2010

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Update: Well, it turns out that while it looks like Venus and Mercury are getting pummeled by Coronal Mass Ejections, the geometry might not work out, at least not for every day that is included in the video above. UT reader Steven Janowiecki brought it to my attention that just because Mercury and Venus look close to the Sun doesn’t mean they’re actually in the line of fire, as they could be well behind or in front of the solar storm. I checked with STEREO project scientist Dr. Joseph Gurman, who took a look at the data. He put together a plot for August 14, (see below) and said, “It shows that Mercury and Venus are well to the East (left) of the Sun-earth line. The large CME on the 14th originated from an active region near the west limb of the Sun, and since most CME’s are about 60 degrees of heliolongitude in width on average, it’s unlikely that that event actually passed by Mercury or Venus.” There was one large event, however, on August 7, that appeared likely to be headed in the direction of Mercury and Venus.

A plot of the STEREO data from August 14, 2010, showing the location of the planets and the two STEREO spacecraft.

So, as it happens sometimes in astronomy, things are not always as they appear, and this exemplifies the challenges of estimating distance in astronomy.

The STEREO website has a very nifty tool where you can see the location of the spacecraft on any date, as well as where the planets are in their orbits. And there is another tool where you can see and download images from a particular day and time and even put together movies of a specific time period showing STEREO data.

Here’s the rest of the article as it ran originally:

Take a look at these Coronal Mass Ejections (CME) from the first part of August 2010, as seen by the two STEREO spacecraft. Here on Earth, we’ve had some aurorae, a result of the recent solar activity. But this STEREO imagery shows Venus and Mercury were blasted by these CMEs.

STEREO consists of two spacecraft – one ahead of Earth in its orbit, the other trailing behind. With this new pair of viewpoints, scientists are able to see the structure and evolution of solar storms as they blast from the Sun and move out through space.

These movies were taken by SECCHI, a suite of remote sensing instruments on both spacecraft consisting of two white light coronagraphs that make up the Sun Centered Imaging Package (SCIP), as well as a Heliospheric Imager (HI).

SECCHI can follow three-dimensional Coronal Mass Ejections (CMEs) from the Sun’s surface, through the corona and interplanetary medium, to impact at Earth. With these instruments, scientists are getting breakthroughs in understanding the origin and consequences of CMEs, in determining their three-dimensional structure, and more, and perhaps be able to predict space weather. Combining STEREO with the new Solar Dynamics Observatory, we’ll be learning more and more about the Sun in the next few years.

As an example of SDO’s capabilities, here’s an SDO image from earlier today showing the Sun’s limb.

View of the Sun from August 18, 2010 from the Solar Dynamics Observatory. Credit: NASA/SDO


Credit: NASA STEREO/NRL

About 

Nancy Atkinson is Universe Today's Senior Editor. She also works with Astronomy Cast, and is a NASA/JPL Solar System Ambassador.

Aqua August 18, 2010 at 7:52 AM

I wonder how much of Venus’ atmosphere gets ‘blasted’ away from the planet during a CME event? Akatsuki, the Japanese Venus probe and the orbiting Venus Express, no doubt got ‘hosed down’! No word at the Venus Express web page about that…

In Frazer Cain’s article, “Is there water on Venus?”, posted July 29, 2009, he quotes 2 X 10^24 Hydrogen atoms are ‘liberated’ every second at Venus. So what’s that mean? More like 2 X 10^26/sec during CME events? Just a guess…

Olaf August 18, 2010 at 3:01 PM

Yes but in order to blast the atmosphere away the particle that collides with Venus atmosphere will lose energy so getting trapped in the atmosphere.

DrFlimmer August 19, 2010 at 12:35 AM

Well, first of all Venus is almost as big as earth meaning its gravity is also similarly strong. The next thing is that Venus’s atmosphere contains a lot of heavy molecules (methane, CO2, a lot of acids), which are not easily stripped away by some protons coming around (otherwise our atmosphere would get lost, too, which is not, or at least the effect is negligible).
The light elements like hydrogen and helium, are already long gone, just as on Earth, as well.

Jon Hanford August 19, 2010 at 3:21 AM

Thanks for the update, Nancy. It answered questions I had on the relative positions of the two planets in relation to the CMEs. I’ve seen a lot of confusion over this issue at other science sites.

Torbjorn Larsson OM August 19, 2010 at 7:07 AM

Um yes, understanding what you are looking at isn’t all that easy.

Even with the funny geometry of the crafts explained, it isn’t all that clear to me what “the pumping” of signal around Venus and Mercury means (H1A most prominently). Depends on if there is “coronagraph” filters and what not over the planets. But the synchronicity is interesting, if not an instrumental artifact.

Speaking of funny geometry, I see in the STEREO home that the crafts aren’t Lagrange placed as the figure may suggest, but slowly drifting from Earth. The inside/outside Earth orbit dots in the picture are actually accurate and meaningful depictions. And STEREO will continue to gain in angular resolution and forecast period for a while.

@ Aqua:

First, it isn’t all that much mass actually, compare with the Avogadro constant of ~ 10^24 molecules/mole.

Second, CME’s and what not are discontinuous phenomena, so for comparison they only bump up observation of Earth losses ~ 60 % IIRC. (OK, that was a very vague memory, so don’t take it as written in stone; I haven’t time to check though.)

DrFlimmer paints the picture, and I don’t think it is cut and dry. [Disclaimer: But I'm a layman, so what do I know.]

Some astrophysicist in a seminar remarked, if I understood him correctly, something along the lines of that magnetic fields may be rather useless as protection in the current solar system (relatively weak CMEs). What protection they provide further away in the gravity well happens over a much larger surface area. So what you gain on the roundabouts you may well lose on the swings.

In which case it may be the gravity well itself that mainly protects the atmosphere. I dunno if enough measurements have been made to make the over all result clear.

Torbjorn Larsson OM August 19, 2010 at 7:14 AM

Also, if the gravity well is the main factor, it would nicely explain the Venus/Earth atmospheres coupled with an absence of plate tectonics on Venus AFAIU. They would have started out with the same heavy CO2 atmosphere.

The mystery then is where the water went on Venus. Photolysis and differential atomic loss, perhaps.

IVAN3MAN_AT_LARGE August 19, 2010 at 10:12 AM

TORBJORN LARSSON OM:

The mystery then is where the water went on Venus. Photolysis and differential atomic loss, perhaps.

I did post a link to this ESA article on a previous occasion, but since you’ve missed (or maybe forgotten) it, here it is again:
Where did Venus’s water go?

IVAN3MAN_AT_LARGE August 19, 2010 at 10:20 AM

Here is another ESA (earlier) article on Venus: Caught in the wind from the Sun.

IVAN3MAN_AT_LARGE August 19, 2010 at 10:25 AM

Furthermore, here is a recent ESA article on Venus: Was Venus once a habitable planet?

Aqua August 19, 2010 at 12:23 PM

@Torbjorn Larsson OM

Its not that much in the way of gas is liberated that I find important here, its that “2 X 10^24 Hydrogen atoms are ‘liberated’ every second” Realizing that there are 86,400 seconds in a day and 31,536,000 seconds in a year… then those numbers do eventually add up… Thanks for the links!

Still… given Venus’ proximity to Sol and the energy carried by a ‘typical’ CME then surely those rates climb exponentially? Here’s hoping the Venus Express can give us a better understanding of those numbers!

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