A fascinating 'new' planet

Feb 11, 2013 by Dr. Tony Phillips 
Mars and Mercury setting together over the Alps on Feb. 8th. Credit: Stefano De Rosa of Turin, Italy

NASA has recently discovered a very strange planet.  Its days are twice as long as its years.  It has a tail like a comet. It is hot enough to melt lead, yet capped by deposits of ice. And to top it all off ... it appears to be pink.

The planet is .

Of course, have known about Mercury for thousands of years, but since 's MESSENGER probe went into orbit around Mercury in 2011, researchers feel like they've been discovering the innermost planet all over again.  One finding after another has confirmed the alien character of this speedy little world, which you can see this week with your own eyes.

Mercury is emerging from the glare of the sun for a beautiful two-week apparition during the month of February 2013.  The show begins about a half hour after sunset. Scan the horizon where the sun's glow is strongest and, if the sky is clear, Mercury should pop out of the twilight, a bright pink pinprick of light.  Mercury itself is not actually pink, but it is often colored so by the rosy hues of the setting sun.

As February unfolds, Mercury will rise higher in the sunset sky, brightening as it ascends.  From February 11th through 21st, the "pink planet" will be visible for as much as an hour after sunset.  February 11th is a date of special interest: a slender crescent Moon will appear straight above Mercury, providing guidance for novice sky watchers.

Mercury circles the sun about three times closer than Earth does, rotating just three times on its axis every two Mercury-years.  This slow-spin under the solar inferno bakes Mercury's surface bone-dry and raises its to 425 degrees Celsius, hot enough to melt lead.  This would seem an unlikely place to find deposits of ice, yet that is what the MESSENGER probe recently confirmed: Mercury has enough ice at its poles to encase Washington DC with a layer of two miles thick.

Ice on Mercury is possible because the tilt of planet's spin axis is almost zero—less than one degree—so there are pockets at the planet's poles that never see sunlight. Shadowed areas at each end of the heavily-cratered planet turn out to be cold enough to freeze and hold water.

MESSENGER found something else: Much of Mercury's ice is coated with a mysterious dark substance.  Researchers don't know exactly what it is, but they suspect it is a mix of complex organic compounds delivered to Mercury by the impacts of asteroids and comets.

In some ways, Mercury itself resembles a with a long tail.  NASA's twin STEREO probes, on a mission to observe the sun, spotted Mercury's tail in 2008.  The MESSENGER probe has since flown through it.  The tail appears to be made of material blown off Mercury's surface by exposure to solar flares and the solar wind at point-blank range.  The pressure of sunlight pushes the tail in the anti-sunward direction, just like the tail of a comet.

With the sun currently approaching the maximum of its 11-year activity cycle, Mercury is getting hit by the stormiest space weather in years.  This is a great time for MESSENGER to study the processes that turn Mercury into a "comet-planet."

Mercury is a strange planet, indeed.  When the sun goes down tonight, step outside and see for yourself.

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User comments : 8

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RealScience
4.8 / 5 (10) Feb 11, 2013
The show begins about a half hour after sunset. Scan the horizon where the sun's glow is strongest and, if the sky is clear, Mercury should pop out of the twilight, a bright pink pinprick of light. Mercury itself is not actually pink, but it is often colored so by the rosy hues of the setting sun.


No, Mercury is NOT 'colored by the rosy hues of the setting sun'.

Mercury can appear 'pink' (or red) at that time for the same reason that the sun appears red at that time (scattering/refraction of bluer wavelengths relative to red during the long path through the atmosphere when near the horizon).

And for a change the mistake is in the article rather than the headline.
grondilu
1.6 / 5 (8) Feb 12, 2013
I'm sorry but I find it very hard to find any interest in Mercury. It's really plain boring however you look at it. It just a big rock too close to the sun. I think it's pretty much the lamest planet in the solar system.
SmokedBort
3.5 / 5 (4) Feb 13, 2013
I'm sorry but I find it very hard to find any interest in Mercury. It's really plain boring however you look at it. It just a big rock too close to the sun. I think it's pretty much the lamest planet in the solar system.


Check out the insane lava flows that occurred there, the surface has been smASHed !
rkolter
5 / 5 (4) Feb 13, 2013
I always liked Mercury. I remember reading everything there was to read about it when I was a kid, which wasn't much. Messenger has sure changed that.
antialias_physorg
4 / 5 (4) Feb 13, 2013
It's really plain boring however you look at it.

Lots of energy there. And we do know that life likes energy gradients. With some of the craters in perpetual night water-ice is a possibility. So definitely worth a look on our search for extraterrestrial life.
_traw_at
3.6 / 5 (5) Feb 14, 2013
For a challenge, how about trying to design a Mercury Landing Craft....one that won't melt in the first few hours on the surface. (hint: use thermoelectric materials to power AND cool the craft...)
Why do this?
Why not? A challenge like this would advance the science of thermoelectric materials.
RealScience
5 / 5 (3) Feb 14, 2013
@_traw_at: thermoelectric materials work through heat flowing across a temperature difference, so the craft will heat up as heat flows through the material to generate power.
And the craft cannot generate enough power from the thermoelectric effect to cool itself back off (even if it uses a maximally-efficient heat pump for cooling).
To paraphrase Homer Simpson, "In this universe we obey the laws of thermodynamics".
pokerdice1
not rated yet Feb 19, 2013
I'm sorry but I find it very hard to find any interest in Mercury. It's really plain boring however you look at it. It just a big rock too close to the sun. I think it's pretty much the lamest planet in the solar system.


I think this post would be worth more than two stars if folks read the post in Napoleon Dynamite's voice. Gosh!!!

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