1 the little desert planet 1. 2 image credit: meridiangraphics.netmeridiangraphics.net mythology 2
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The Little Desert Planet
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Mars Mythology (Greek & Roman)
• Son of Zeus (Jupiter) & Hera (Juno)
• Grandson of Cronos (Saturn)
• Half-brother to Hercules & Orion
• Considered to be father of Romulus & Remus, founders of Rome, by the Romans.
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Mars Mythology (Greek & Roman)• The ancient Greeks believed him to be the
father of Phobos (Fear) and Deimos (Panic). Aphrodite (Venus) was their mother.– ‘Phobos’ gives us our word ‘phobia’.– ‘Deimos’ gives us our words demon &
demonic.
• Mars (Ares) was, ironically, the patron god of both warfare and agriculture!
Image Credit: plantpath.ifas.ufl.edu/
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Mars’ Physical Properties
Mars isroughly½ ofEarth’sdiameter.
Image Credit: rst.gsfc.nasa.gov/Sect19/ br_earth-mars-front.jpg
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Mars has a mass about 11% that of theEarth. The Earth is 9.3 x heavier!
Image: www.space.gc.ca
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Mars’densityis 3.94g/cm3.
Earth’sis 5.5g/cm3.
??????
Image Credit: www.astro.czuby.net7
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Conclusion:Mars’ core isproportionatelysmaller thanEarth’s core.
Image credit: www.psrd.hawaii.edu
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Orbit & RotationNot Too Different From Ours
• Average distance from the sun:
228 million km (1.52 A.U.)
• Perihelion: 207 million km.
• Aphelion: 249 million km.
• Orbit eccentricity: 0.0935 (very elliptical)
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Familiar Orbit
• Orbital period: 687 days or 1.88 years
• Inclination of orbit to ecliptic: 1.85o
– This is enough to benoticeable to the naked eye.
• Minimum distance from earth is 55 million km, at opposition. Maximum is 401 million km, at superior conjunction.
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Familiar Orbit
• Due to the 1.88 year orbit, seasons on Mars would last about 5½ months on average! But…the Martian summer is over a month longer than the winter, due to Mars’ elliptical orbit!
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The 2003 oppositionwas here
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Familiar Rotation
• Mars rotates in the normal (prograde) direction in 24 hours 37 minutes. (Sidereal period)
• Its noon-to-noon day is 24 hours 40 minutes. (Synodic period)
• Axis is tilted 25.2o relative to its orbit.
• Fast rotation, yet no magnetic field.– Conclusion?
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Mars’ Interior• Our conclusion may be wrong!
• "Mars is influenced by the gravitational pull of the Sun. This causes a solid body tide with a bulge toward and away from the Sun (similar in concept to the tides on Earth). However, for Mars this bulge is much smaller, less than 1 centimeter (0.4 inch). By measuring this bulge in the Mars gravity field we can determine how flexible Mars is. The size of the measured tide is large enough to indicate the core of Mars can not be solid iron but must be at least partially liquid." (Dr. Charles Yoder – JPL Planetary Sci.)
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Almost no magnetic field
• Mars has no internally-produced magnetic field (no internal dynamo), even though it rotates almost as fast as earth does.
• Solar wind interacts with the thin atmosphere to produce an ionosphere, which produces an induced magnetosphere.
• The bow shock is located only ¼ of a Martian diameter out from the surface (1700 km).
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Strength is1/10,000th ofearth’s field.
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Mars’ magnetic field
• What little bit of magnetism Mars does have is broken up into smallregions – it’s not planet-wide like the earth’s.
• If the interior of Mars is still at least partly molten, and Mars rotates fast, why no magnetic field? Hmmmm……..!?
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photojournal.jpl.nasa.gov
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• What does this mean for colonization of Mars?
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In the late 1800’s, anItalian astronomer,Giovanni Schiaparelli,thought he saw longstraight “canali” orchannels on Mars.
He drew hisobservations……..
phys-astro.sonoma.edu
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Schiaparelli didn’t make any claims aboutwhat these channels were…but someoneelse did. http://history.nasa.gov/SP-4212/p6.jpg
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Percival Lowell• Wealthy American Astronomer Percival
Lowell mistook the Italian word “canali” to mean “canals”. (Maybe a natural mistake!)
• He used his own money to build theLowell Observatory near Flagstaff, Arizona, to study these “canals”.
• Lowell concluded that these “canals” had been built by intelligent “Martians”.
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23http://www.lowell.edu/AboutLowell/PLportrait.jpg
www.hencoup.com
Lowell at his telescope.
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Lowell’s observatoryand telescope.
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Lowell’s legacy lives!
• Lowell’s idea about intelligent Martians became very popular with the American public.
• Much of our early (and present) science fiction comes from this idea.
• H.G. Wells’ “War of the Worlds” was based upon this idea.
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The War of the Worlds
www.cloudster.com/Sets&Vehicles/WarOfTheWorlds
drzeus.best.vwh.net/ wotw/illus/interior.html
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“This is Glub, sitting in for Tom Dunn on the‘Eleven O’Clock News,’ and I wish to announce thatthere has been a rather sudden and sweepingchange in your government.
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We still havelittle green men – a coincidence?
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