Transcript Mercury 30 million miles from Sun

mercury
Mercury: Planet, Ancient Greek God or Greatest Rock Star?
• Johnny Depp is reportedly being
considered for the starring role in a
new biopic about the life of
Freddie Mercury in development
by Robert De Niro's Tribeca
Productions according to Queen
guitarist Brian May.
Figure 1. Freddie Mercury, lead singer
of the legendary band, QUEEN and
greatest rock, ever
begin solar system tour
no, it’s
not to
scale
solar system to scale (relative size but not distance)
Mercury
30 million
miles
from Sun
“The Fun in the Sun Planet!”
Who was Mercury?
• The Romans named
Mercury after the fleetfooted messenger of the
gods because it appeared
to move across the sky
faster than any other
planet. In mythology,
Mercury is the god of
travel, commerce and
thievery, and is
counterpart to the Greek
god Hermes.
The other Mercury
• Historically, Mercury has
been observed all the
way back to the
Sumerians of 3rd
millennium BC and also
the Greeks who have
given the planet two
names: Apollo and
Hermes: Apollo for its
appearance in the early
morning while Hermes
as the evening star.
Visiting Mercury? Consequences
of no atmosphere
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No weather.
No weathering.
No wind.
No clouds.
No hang-gliding.
Only erosion from
gravity and
micrometeorite
bombardment.
• Instant tan.
• Use sunscreen with
SPF 4000000
• This will never happen.
Why no atmosphere?
• During its visit to Mercury, Mariner
10 detected a tiny amount of
helium 1000-km above the surface
as well as traces of sodium,
potassium and oxygen. Aside from
these elements, Mercury has
almost no atmosphere due to an
interaction between the planet's
magnetic field and the Sun.
Combined with the Sun's solar
wind and Mercury's extremely high
temperatures, atoms of the
atmosphere are constantly blasted
into space. However, it is also
constantly replenished by the
capturing of solar wind particles
and radioactive decay of Mercury's
crust.
Highs & Lows
• Because it is so close to the
Sun, temperatures on its
surface can reach a
scorching 467 degrees
Celsius (900 F). But because
the planet has hardly any
atmosphere to keep it warm,
nighttime temperatures can
drop to a frigid -170 degrees
Celsius (-200 F).
Mercurian Time
• Mercury completes
a trip around the
Sun every 88 days,
speeding through
space at nearly 50
km per second,
faster than any
other planet.
Being on Mercury
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If an explorer stepped onto the surface of Mercury, he would see the most peculiar
sights. On one perspective, the explorer would observe the rising of the Sun but
suddenly and unexpectedly, the Sun would stop, go backwards, stop again and head
off toward the other horizon.
In addition, the stars would be zooming across the sky at three times the speed!
Other observers at other points of view would see different but equally strange
sights.
A day on Mercury
• http://btc.montana.edu/messenger/Interactives/
ANIMATIONS/Day_On_Mercury/day_on_mercury
_full.htm
• http://btc.montana.edu/messenger/Interactives/
ANIMATIONS/Orbit_Rotation/orbit_rotation_full.
htm
Only Visitors from Earth: Mariner 10
and Messenger (from the USA)
• Mariner 10
• Mission: Venus &
Mercury Flyby
• Launched: November 3,
1973
• Mariner 10 was the first
mission to use the
gravitational attraction of
one planet to reach
another. On November 3,
1973, Mariner 10 was
launched toward Venus,
reaching the Venusian
atmosphere on February
5, 1974.
Messenger:
MErcury Surface, Space ENvironment,
GEochemistry and Ranging
http://www.nasa.gov/mission_pages/messenger/main/index.html
• Why is Mercury so dense?
• What is Mercury’s
geologic history?
• What are the structure
and state of Mercury's
core?
• What is the nature of
Mercury's magnetic field?
• What are the unusual
materials at Mercury's
poles?
• What volatiles are
important at Mercury?
Messenger: A Robot Spacecraft
Messenger during assembly and testing
Messenger readied for launch.
Launch of Messenger, 2004
Leaving Earth
Where is Messenger now?
This image shows MESSENGER's location in its current orbit (in pink). The image also shows the
orbits and current positions of Mercury, Venus and Earth. Positions of stars with magnitude 9 or
brighter are shown from this perspective that is above the Sun and north of Earth's orbit.
Stuff about Mercury
• http://www.messengereducation.org/Interactives/ANIMATIONS/kiosk
/index.php
Messenger
looks back,
waves
goodbye to
us. This is
also how it
sees
Mercury—
can you spot
evidence of
tectonics?
Mercury: Geology
• On its surface, Mercury closely
resembles our Moon. Impact
craters cover the majority of the
planet but unlike the Moon,
Mercury’s cratered upland
regions are covered with large
areas of smooth plains. The most
distinguishing features on
Mercury’s surface are scarps, or
long cliffs. These wind across
Mercury’s surface for tens to
hundreds of kilometers and
range from 100 meters to over
1.5 kilometers in height. What
makes these cliffs so unique is
that no other planet or moon
features such a vast number of
them. They are thought to be
thrust faults created when the
planet, as it cooled, shrunk by up
to 4 km in diameter.
Mass and Density
• In 1841, the German astronomer Johann Franz Encke determined Mercury’s
mass by measuring its gravitational effect on a comet that now bears his name.
This measurement was within 20% of the best modern measurement of 3.3 x
1023 kilograms, or about 5.5% of Earth’s mass.
• Knowing the mass of Mercury doesn’t tell us its exact composition, but since
we know the planet’s volume as well, we can estimate what the interior is
made of. We start by dividing the planet’s mass by its volume to find its
average density. Each element or compound has its own characteristic density,
and a planet is made up of many materials of different densities. From the
average density, scientists can guess what materials, and how much of each,
the planet contains.
• For example, Earth has an average density of 5.5 g/cm3, which is between the
density of iron (8 g/cm3) and that of the silicate compounds found in rocks (3
g/cm3). We believe that Earth has an interior core of iron making up about 16%
of the Earth’s volume. Mercury has a density similar to Earth, 5.4 g/cm3.
Because of Mercury’s small size and high density, scientists believe that about
70% of Mercury’s mass is composed of iron, mostly contained in its core.
Mercury on the inside
Messenger view of scarps
Bird’s eve view of scarp
Cool Quiz: click on the link below!
• Quiz here