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Mercury images- Similar to our Moon
Venus & Mercury
2-8-07
I. Mercury
A. 0.4 AU
from sun
1.
A.U.=
Astronomical unit
= 93,000,000 miles
This is the distance of Earth from
Sun so we compare all planets
to our distance.
2. close to sun in
sky
a) morning or
evening “star”
( not a star but looks like one. )
b) poor photos
Earth’s
atmosphere
distorts image
Earth View
B. Rotation
1. once in 59
Earth days
(siderial period)
Siderial means with respect to stars.
C. Revolution
1. once in 88
Earth days
Time to go once around the
Sun.
D. Length of
day
(solar rotation)
1. 176 Earth days
This is a strange effect. Look at the diagrams and I
will explain it when I return.
2. One
Mercury day =
2 Mercury
years
3. Determine
motion by
RADAR
Radio detection and
ranging
E. Temperature
o
800 F
o
-280 F
F. Albedo=
1. Light reflected
Light received
2. Mirror albedo is 90%
Black is 0%
Mercury is 6%
3. Dark, like
moon
G. Mass
1. 5.5% of
Earth
H. Density
1. same as Earth
2. must have iron core
I. Spacecraft
Observations
1. unmanned
2. Mariner 10
a) 3 flybys
b) 1974
3. Messenger Mission
Left Earth August 2004
Arrived at Mercury in 2011
Still There
4. Photographs
a) craters
flatter than
moon
Why?
greater gravity
softer surface
eroded
b) maria
c) scarps
cliffs hundreds
of miles long
Scarps are
wrinkles....
Cracks in the
crust
scarp
scarp
scarp
scarp
4-22-13
d) Weird Terrain
Grooved areas
with smooth
area in between
weird
terrain
weird
terrain
weird
terrain
Cause?
o
180 from large
crater
recombined
shock waves
from meteorite
impact created
Weird Terrain
5. Atmosphere
a) small
b) sodium,
helium
c) coming from
craters?
6. Magnetic
field
a) yes
6. No moons
7. origin very
different from
moon
I. Mercury
A. 0.4 AU
from sun
Views from Messenger at Mercury
Spider Crater
Views from Messenger at Mercury
Views from Messenger at Mercury