Mercury is Less Like the Moon than Previously Believed

With Mercury fading in MESSENGER’s rear view mirror, scientists are just starting to pore through the torrent of images sent back. And as you can probably guess, the new mysteries are piling up fast and furious. The planet is much less like the Moon than scientists previously thought.

MESSENGER made its closest approach to Mercury on January 14, passing just a few hundred kilometres above its surface. During the flyby it captured a total of 1,213 images.

One of the most unique features discovered by MESSENGER has been dubbed “The Spider” by scientists. And that’s what it looks like. The feature has a central crater surrounded by more than a hundred narrow, flat-floored troughs (called graben) radiating away.

Unlike the Moon, Mercury has huge cliffs or scarps, which can snake hundreds of kilometres across the planet’s surface. They trace the lines of old volcanic faults, from when the planet was still geologically active.

Because of its small size and high density, Mercury has a surprisingly large pull of gravity. Astronauts walking around its surface would experience 38% of the Earth’s gravity. This higher gravity means that the impact craters look different. Material doesn’t splash out from the impact craters so far, and there are many more secondary crater chains.

“We have seen new craters along the terminator on the side of the planet viewed by Mariner 10 where the illumination of the MESSENGER images revealed very subtle features. Technological advances that have been incorporated in MESSENGER are effectively revealing an entirely new planet from what we saw over 30 years ago,� said Science Team Co-Investigator Robert Strom, professor emeritus at the University of Arizona and the only member of both the MESSENGER and Mariner 10 science teams.

MESSENGER wasn’t just taking pictures. It also had a suite of scientific instruments measuring many features of the planet. Perhaps the most puzzling of these is its magnetic field. Even though Mercury cooled down and solidified eons ago, it still has an magnetic field. This was first detected by Mariner 10, and MESSENGER confirmed it.

This is just the beginning. MESSENGER will return to Mercury on October 6, 2008 to make a second flyby, and then a third on September 29, 2009. The spacecraft make its final return to the planet on March 18, 2011 when it’ll begin a year-long orbital mission.

Original Source: MESSENGER News Release

13 Replies to “Mercury is Less Like the Moon than Previously Believed”

  1. Fascinating new info! The “Spider” looks rather a lot like Mercury’s bellybutton 😛

  2. Fraser said:
    “Unlike the Moon, Mercury has huge cliffs or scarps, which can snake hundreds of kilometres across the planet’s surface. They trace the lines of old volcanic faults, from when the planet was still geologically active.”

    John says:
    There are plenty of huge cliffs and scarps on the Moon too — but you have to look out for them. The Altai Scarp around Mare Nectaris (actually believed to be an outer impact ring produced as a result of the underlying rock rippling outwards from the impact) is just one example a huge scarp that can easily be seen (using binoculars or a telescope) during low sun angles, while the cliffs of the Apennines Mts, for example, around Mare Imbrium stretch for 600 km and are upto 5 km high. Plenty more of the above can be seen around most of the basins, so do have a look!
    As for vollcanic faults/features etc., the Moon is also covered in these — some of which are arcuate (arc-like) to the basins that formed. Rilles, wrinkle ridges, colour in mare material are just a few of the features to look out for here (could give examples here but so many to mention) — all of which underlie the moon past violent volcanic history.
    John —

  3. Maybe my humor is a tad darker but it looks alot more like its anus. :)To a more serious side of things, i have to say that is one of the most unique craters i’ve seen. It just looks bizzare. Very cool.

  4. Mercury is the second densest planet, with Earth being the denser. Yet, when comparing the vast difference in planet sizes, Mercury has the largest iron core in the solar system. Mercury has only a very thin outer crust comparitively. With an iron core, there is magnetivity. Add in the super close bombardment of ions in the solar wind, a magnetic field seems perfectly plausible.

  5. “One of the most unique features . . . �
    Unique means the only one. You cannot have a most unique anything. It is either unique, or it is not.

  6. Why are we still getting only low resolution photos from Mercury? NASA isn’t usually this stingy will megabites.

  7. Mercury has liquid core

    The statement “Even though Mercury cooled down and solidified eons ago, it still has an magnetic field. “, is probably not correct. One would expect that such a small planet would have cooled but measurements indicate this is not the case.

    I read the following in science news a while ago.

    I also had the good fortune to sit next to Jean-Luc Margot of Cornell University at a conference dinner. It gave me the opportunity to express my amazement at the insight required to realize that the radar instruments could even detect the difference in wobble a solid core verses a liquid core would impose on Mercury. (It is easier to rotate a liquid can of soup compared to a frozen can of soup.).

    I am not a fan of the sulfur explanation for the heat necessary to keep the core liquid. I believe further analysis will show intense radioactive activity due to radioactive elements in the core of Mercury. If this is the case, Mercury will be a source of energy, forcing another “Space Race�.

    john kulick AKA Snowflake Universe

  8. Is it just me or does anyone else have this problem?

    When I look at photos like the one attached to this story I find it difficult to see the craters as being concave. My brain turns them into convex mounds.

    I don’t normally have such a problem with other images. “innies” and “outies” are correctly identified in the main.

    My solution if I can’t view it correctly is to rotate the image. Any simple image editing app lets you do this. (Just Copy the image then Paste it into the image app).

    I assume it is because my brain expects the lighting to come from the top of the image. Rotating it allows me to try out various lighting directions until I get the one my poor dumb brain can work on.

    Thanks for listening….

  9. Hi Pete, that happens to me too. Most times I canactually get my brain to flip the image between mounds and craters, but sometimes its very difficult. I look or the shadows and sometimes that helps. I never tried rotating the image though.


  10. I’m with you too, Pete

    Sometimes it takes me a while but I consider it a challenge to fight the initial understanding and right the picture internally. Then you can relax and let it slip right back to an outie.
    If Mercury was solid all the way through (and I take it it isn’t) then could the whole planet be a permanent magnet? Would that explain the magnetic field?
    One more thing. If it is heated through radioactivity, I suspect that it would be deep enough to still make it a pretty expensive proposal to mine it for energy resources. Wouldn’t a solar array on the surface be cheaper?

  11. If you see craters as convex shapes resolution into concave is quite simple; move the ambient light source you are using 180 degrees relative to the picture. Your brain interprets the highlighted bits of a picture as aligning to the natural light, so if the highlights on the picture are to the right and your light source is on the right, craters will appear convex..

  12. Sub: Mercury interlinks
    One must search for Base Functional Index beyond the Gravity frame of Mind that forms an essential link to Magnetic Fields and aligned flows both in curvature modes and straight-modes. Search for DMVT Process-
    Double Magnetic Vortex Tube Process
    Vidyardhi Nanduri
    Cosmology Interlinks Vedas

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