Transcript Mercury Powerpoint notes

Mercury
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Orbital Properties
Viewed from Earth,
Mercury is never
far from the Sun
and can be viewed
shortly before
dawn or right after
sunset
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Orbital Properties
Phases of Mercury can be seen best when it
appears furthest from the sun.
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Physical Properties
Radius
Mass
Density
Moon
Mercury
Earth
1738 km
2440 km
6380 km
7.3 × 1022 3.3 × 1023 6.0 × 1024
kg
kg
kg
3300 kg/m3 5400 kg/m3 5500 kg/m3
Escape
Speed
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2.4 km/s
4.2 km/s
11.2 km/s
Surface Features
Mercury cannot be imaged well from Earth; best
pictures are from Messenger
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Surface Features on the Moon
and Mercury
Cratering on
Mercury is similar
to that on Moon
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Rotation Rates
Mercury was long thought to be tidally locked to the
Sun; measurements in 1965 showed this to be false.
Rather, Mercury’s day and year are in a 3:2
resonance; Mercury rotates three times while going
around the Sun twice.
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The Surface of Mercury
Mercury is less heavily cratered than the Moon
Some distinctive
features:
Scarp (cliff), several
hundred kilometers
long and up to 3 km
high
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The Surface of Mercury
Caloris Basin,
very large impact
feature (a bull’s
eye crater) on
opposite side of
planet
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8.6 The Surface of Mercury
“Weird terrain” is thought to result from
focusing of seismic waves
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Interiors
Mercury is much denser than the Moon and has
a weak magnetic field—not well understood!
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Evolutionary History of Mercury
Mercury much less well understood
• Formed about 4.6 billion years ago
• Melted due to bombardment, cooled slowly
• Shrank, crumpling crust
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Messenger hit the surface of
Mercury on Thursday April 30, 2015
Last picture:
http://www.theverge.com/2015/5/1/8527957/mes
senger-last-image-mercury
NASA on Messenger
http://www.onenewspage.com/video/20150417/2
772494/NASA-MESSENGER-Mercury-MissionIs-About-to.htm
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MESSENGER and Shadows
The MESSENGER mission to Mercury is a great
engineering challenge because of the high temperature
environment in which the spacecraft will operate.
At Mercury’s distance from the Sun, the solar radiation
will reach levels 5-11 times as high as they are in space
near Earth.
MESSENGER spacecraft will be exposed to more
than 20 times the amount of solar radiation as it
would on the surface of Earth.
This creates an environment for the spacecraft where
temperatures can reach well over 400˚C (750˚F).
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Let’s experiment!
You and a team will construct a simple device to examine
how substances can be protected from sunlight. You will
place an ice-water mixture in a coffee can and use a
sunshade to protect the contents from sunlight. Based on the
amount of ice that melts during the experiment the
effectiveness of your shade can be estimated.
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