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TOPIC: Mercury


L

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RE: Mercury
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On January 14, 2008, MESSENGER passed 200 kilometres above the surface of Mercury. This image shows a view looking toward Mercurys south pole. At the bottom left of the image the terminator can been seen.

SouthpoleMerc_ge3
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Credit: MESSENGER Teams, JHU APL, NASA

This image was acquired about 98 minutes after MESSENGER's closest approach to Mercury, when the spacecraft was at a distance of about 33,000 kilometres.


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Images from NASA's Messenger spacecraft hint at the presence of solidified lava flows on the surface of Mercury. If confirmed, they should provide crucial clues to unlocking the planet's history.

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This is an image of the limb of Mercury taken by MESSENGER as it approached the planet from about 1 1/2 Earth diameters away.

messMerge1
Expand (218kb, 1024 x 895)
Credit: MESSENGER Teams, JHU APL, NASA

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Caloris Basin
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The Caloris Basin, also called Caloris Planitia, is an impact crater on Mercury about 1350km in diameter, one of the largest impact basins in the solar system. Caloris is Latin for heat and the basin is so-named because the Sun is almost directly overhead every second time Mercury passes perihelion.

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RE: Mercury
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On January 14, 2008, the MESSENGER spacecraft observed about half of the hemisphere missed by Mariner 10. This image was taken by the Wide Angle Camera, part of the Mercury Dual Imaging System (MDIS) instrument, and through a filter sensitive to light near the red end of the visible spectrum (750 nm).

WAC1
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Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington

This image was taken about 80 minutes after MESSENGER's closest approach to Mercury (2:04 pm EST), when the spacecraft was 27,000 kilometres away.
The image shows features as small as 10 kilometres in size.

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Mercur
A series of images taken between Jan. 9 and Jan. 13 as the Messenger spacecraft approached Mercury.
Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington

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Average Distance From Sun: 58 Million KM
Nearest Distance to Earth: 85 Million KM
Temperature on Sunlit Side: 400C
Temperature on Dark Side: -170C
Diameter: 4880 KM
Mass: 0.056 Earth Standard
Gravity: 0.38 Earth Standard
Atmosphere: Traces of Helium, Neon, Argon
Moons: None
Mercury Year: 88 Earth Days
Mercury Days: 59 Earth Days


Mercury is the closest planet to the Sun.

In 1974 the US space probe Mariner 10 discovered that its surface is cratered by meteorite impacts. Its largest known feature is the Caloris Basin, 1,400 km, There are also cliffs hundreds of kilometres long and up to 4 km high, thought to have been formed by the cooling of the planet billions of years ago.
Inside is an iron core three-quarters of the planet's diameter, which produces a magnetic field 1% the strength of the Earth's.

click here! to go to Transit page.

Being the closest planet to the sun, Mercury has to endure extremely high temperatures and any atmosphere there may have been, would have been burnt off long ago. A mystery is why has mercury still got a molten core, and magnetic field; it should have cooled down long ago.
Mercury usually appears as a bright "star" with a yellowish or ochre hue. At its best evening apparitions, it can be found almost directly above where the Sun has set, being visible for up to 90 minutes after sundown.
During its best morning apparitions, you'll find it positioned almost directly above where the Sun will rise up to 90 minutes prior to sunrise.


spacer.gif Click, for CalorisBasin

Click to Expand !

click here! for large colourmap
click here! for large bumpmap
click here! for large photo of Mercury.
Currently, a spacecraft called, MESSENGER, is on it`s way to visit Mercury.
The flybys will have approach phase angles of 112 (in October 2007) and 129 (July 2008). The angles correspond to the Sun lighting 1/3 and 1/5 of the surface facing MESSENGER as the spacecraft approaches.
MESSENGER can view opposite sides of the never-before-imaged hemisphere of Mercury soon after minimum altitude passage.
click here! to read more.
During the Mercury flybys MESSENGER will map nearly the entire planet in color, image most of the part of the planet unseen by Mariner 10, and take reconnaissance measurements of surface, atmosphere and magnetosphere composition. This would be a full science return for some missions, but it is just the start for MESSENGER. The flyby results will be invaluable for planning the yearlong orbital mission that follows.


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Mercury magnetic field
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Mercury's puny magnetic field may be so weak thanks to constant wrangles with the solar wind.
NASA's Mariner 10 mission detected a magnetic field around our solar system's innermost planet in 1974, but its cause remained a mystery - until recent measurements suggested that Mercury's core may be partly molten. As with Earth, these "moving parts" could act like a dynamo, generating electricity and consequently a magnetic field. But that cannot explain why Mercury's field is so weak, says Karl-Heinz Glassmeier at the Institute for Geophysics and Extraterrestrial Physics at Braunschweig, Germany.

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RE: Mercury
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Title: A Side of Mercury Not Seen By Mariner 10
Authors: Gerald Cecil, Dmitry Rashkeev (University of North Carolina at Chapel Hill)
(Version v2)

More than 60,000 images of Mercury were taken at ~29 deg elevation during two sunrises, at 820 nm, and through a 1.35 m diameter off-axis aperture on the SOAR telescope. The sharpest resolve 0.2" (140 km) and cover 190-300 deg longitude -- a swath unseen by the Mariner 10 spacecraft -- at complementary phase angles to previous ground-based optical imagery. Our view is comparable to that of the Moon through weak binoculars. Evident are the large crater Mozart shadowed on the terminator, fresh rayed craters, and other albedo features keyed to topography and radar reflectivity, including the putative huge "Basin S" on the limb. Classical bright feature Liguria resolves across the northwest boundary of the Caloris basin into a bright splotch centred on a sharp, 20 km diameter radar crater, and is the brightest feature within a prominent darker "cap" (Hermean feature Solitudo Phoenicis) that covers the northern hemisphere between longitudes 140-250 deg. The cap may result from space weathering that darkens via a magnetically enhanced flux of the solar wind, or that reddens low latitudes via high solar insolation.

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Title: A Side of Mercury Not Seen By Mariner 10
Authors: Gerald Cecil, Dmitry Rashkeev (University of North Carolina at Chapel Hill)

More than 60,000 images of Mercury were taken at ~29 deg elevation during two sunrises, at 820 nm, and through a 1.35 m diameter off-axis aperture on the SOAR telescope. The sharpest resolve 0.2" (140 km) and cover 190-300 deg longitude -- a swath unseen by the Mariner 10 spacecraft -- at complementary phase angles to previous ground-based optical imagery. Our view is comparable to that of the Moon through weak binoculars. Evident are the large crater Mozart shadowed on the terminator, fresh rayed craters, and other albedo features keyed to topography and radar reflectivity, including the putative huge ''Basin S'' on the limb. Classical bright feature Liguria resolves across the northwest boundary of the Caloris basin into a bright splotch centred on a sharp, 20 km diameter radar crater, and is the brightest feature within a prominent darker ''cap'' (Hermean feature Solitudo Phoenicis) that covers much of the northern hemisphere between longitudes 80-250 deg. The cap may result from space weathering that darkens via a magnetically enhanced flux of the solar wind, or that reddens low latitudes via high solar insolation.

mar10_full_2
Expand (322kb, 1024 x 1065)
Montage of some previous maps of Mercury and our data, cylindrical equidistant projection. (a) Mariner 10 photo map at left, at right is a mosaic of Arecibo radar images with a few showing north-south Doppler ambiguities (Harmon et al. 2007); (b) An example Mariner far image blurred to our resolution at left, Ksanfomality (2004)'s combination of the Baumgardner et al. (2000) and Dantowitz et al. (2000) Mount Wilson images in the middle, and at right our SOAR data.

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