Download HERE

Observing Mars
By
Brad Jarvis
Overview
•
•
•
•
•
•
•
Basic facts
Orbits and distance
Viewing Mars from Earth
The view from space
Current exploration
Conclusion
References
Basic Facts about Mars
•
•
•
•
•
•
Location is fourth from the Sun
Day is about the same as an Earth day
Year is nearly two Earth years long
Size is half Earth’s, with about the same land area
Gravity is about 1/3 that of Earth
Atmosphere is mostly CO2 at less than 1% the air
pressure on Earth
• Temperature is -125°F to -13°F
• Two moons are possibly captured asteroids
Orbits and Distance
Mars is:
•35-63 million miles away from
Earth at opposition
•128-142 million miles away from
the Sun
Viewing Mars from Earth
Viewing Mars from Earth
Apparent Size
The apparent size of Mars varies between 14 and 25 arcseconds at opposition
(1/133 and 1/75 the apparent size of the Moon)
Viewing Mars from Earth
Albedo Features
Common types of features:
Lacus (lake), Mare (sea), Regio (region), Sinus (bay)
Map courtesy Daniel Troiani (producer), Carlos Hernandez (named features), ALPO
Viewing Mars from Earth
The Colors of Mars
• Red is the color of iron-rich dust
• Dark gray is the color of volcanic rock
• White is the color of ice
Viewing Mars from Earth
Changes in Appearance
•
•
•
•
•
Apparent tilt of poles varies with relative positions of Earth and Mars
Sizes of polar regions get smaller in summer and larger in winter
Clouds can be white (water and CO2 ice) or red (dust)
Dust storms usually occur in southern summer and may engulf the planet
Features appear dark or light depending on presence of dust
The View from Space
Dust storm from Hubble Space Telescope
The View from Space
A Confusion of Orientation
• Earth-based photos and maps are oriented so that south is up
• Space-based photos and maps are oriented so that north is up
• There have been two different longitude references for spacebased maps since 2002
The View from Space
Mapping the Surface
Common types of features:
Chasma (chasm), Fossa (long valley), Mons (mountain), Patera (crater), Planitia (plain),
Planum (plateau), Terra (land), Tholus (hill), Vallis (valley), Vastitas (lowland)
The View from Space
Martian Geology
The View from Space: Martian Geology
Cratered Terrain
Noachis Terra
(Noachis)
•
•
Older parts of Mars are heavily cratered
Typically in the southern hemisphere
The View from Space: Martian Geology
Northern Plains
•
•
Younger parts of Mars are lightly cratered
Typically in the northern hemisphere
The View from Space: Martian Geology
Channels and “Canals”
Xanthe Terra
(Oxia Pallus)
•
•
Water likely carved channels in the surface
Some of the famous “canals” seen from Earth may have dust
blown by the wind
The View from Space: Martian Geology
Valles Marineris
•
•
Valles Marineris is the largest canyon in the Solar System. It is the width of
the lower 48 states of the U.S. and up to four miles deep.
It is a fracture caused by the uplift of volcanoes in the Tharsis region .
The View from Space: Martian Geology
Tharsis and Olympus Mons
•
•
Tharsis is a region where the crust has uplifted. It is about 2,500 miles
across and six miles high.
Sitting atop this uplift are shield volcanoes, the largest of which is
Olympus Mons. It is over 300 miles across, and 15 miles high.
The View from Space: Martian Geology
Hellas
•
•
Hellas Planitia is one of two large impact basins (Argyre Planitia is the
other). It is 1,100 miles across and five miles deep.
It is full of fast-cooling dust. It has been seen with frost and haze in the
mornings.
Current Exploration
• Two Mars Exploration Rovers (left) will land on opposite sides of
Mars in January 2004. They will study rocks over a maximum range of
about 3/4 mile per day.
• Mars Express (including an orbiter and lander, right) will arrive at
Mars in December 2003. It is the first mission since Viking to look for
life.
Conclusion
Mars is an entire world, with the same amount of land as Earth,
and it is only six months away.
It is an interesting place that can be explored by telescope, by
robot, and eventually by people.
References
Books:
•
•
•
Boyce, J. (2002). The Smithsonian Book of Mars. Washington: Smithsonian Institution Press.
Beatty, J., Petersen, C., Chaikin, A., eds. (1999). The New Solar System, 4th Ed. Cambridge: Sky
Publishing Corp.
Hartmann, W. (2003). A Traveler’s Guide to Mars. NY: Workman Publishing.
Web:
•
•
•
•
•
•
ALPO Albedo Map [http://science.ksc.nasa.gov/mars/mpf/marswatch/marsnom.html]
Mars Exploration Rover [http://mars.jpl.nasa.gov/mer/]
Mars Express [http://sci.esa.int/science-e/www/area/index.cfm?fareaid=9]
Mars Gazetteer [http://planetarynames.wr.usgs.gov/TOCmarsmain.html]
Mars Section Observing Alert and Images Page
[http://www.lpl.arizona.edu/%7Erhill/alpo/marstuff/recobs.html]
Mars Society [http://www.marssociety.org]
Software:
•
•
Starry Night Pro (Space.com)
The Guide (Project Pluto)
Photos Courtesy: Tim Brown