1Mercury12Mercury•When we talk about a planet we candefine some different rotational periods.•year– this is how long it takes an object toorbit the sun.•rotation on the axis- this is how long ittakes an object to turn on its axis•day-the period from sunrise to sunrise3•For example in the case of Mercury, theyear is 88 Earth days long,•the rotation on its axis is 59 days long.•This is a ratio of 3:2- we refer to this as aresonance since there is a numberrelationship.•As a result of the these two times beingclose, the time between sunrises onMercury is actually 176 days.
2•As a result of the these two times beingclose, the time between sunrises onMercury is actually 176 days.45
37Basic facts•Since Mercury also has a diameter of only4900 km, it is not big enough to hold ontoany significant atmosphere. As a result thetemperatures from the dark to the lightside vary from 100 Kto 700K.8Interior•Mercury does seem to have an significantiron core, and a weak magnetic field about1% the strength of Earth’s. Recent resultsconfirm that at least the outer part of thecore is molten and that the core makes upas much as85% of the interior• enger/media/PressConf20120321.html•The internal structure of Mercury is verydifferent from that of the Earth. The core isa much larger part of the whole planet inMercury and it also has a solid iron-sulfurcover. As a result, the mantle and crust onMercury are much thinner than on theEarth.9
4Earth vs Mercury InteriorCredit: Case Western Reserve UniversityRead more: -wrinkled-mercury-is-full-of-surprises/#ixzz2YBHr7uiv1011Scarps•Mercury does have a feature called‘Scarps’. These are long shallow cliffs thatextend for hundreds of kilometers. Thesescarps may actually be evidence of ashrinking planet. Mercury may haveshrunk by as much as 1-3 km.
5Caloris Basin•This is a relativelyyoung and massiveimpact basin on theMercury.13•The impact thatcreated Caloris wasso massive in createda compressive wavethat altered the otherside of the planet..1415Current missions•Currently Messenger(messenger.jhuapl.edu) there nowLaunched Aug. 2004•first flyby Jan142008,•second flyby Oct. 6 2008•goes into orbit March 2011• Bepi Colombois anotherplannedmission with a launch date Jan 2015
616Messenger Flybys• ml• ml•These pages show images from the recentflybys.These are more detailedobservations than have every been done.17The surface of Mercury looks mostlike1. Earth2. MoonResponseCounter18•The two flybys of MESSENGER havephotographed large areas of the surfacethat had not been previously been imaged.
719From Mariner 10we had 45% of the surfaceimages.With the two subsequent flybys ofMessenger we now have about 90%NASA/Johns Hopkins University Applied Physics