1. Earth & Mars As Different as they are Alike
Interest in Mars began long before we were able to send spacecraft to the Red Planet—as Mars is commonly referred as. Earth is often called the blue planet. Early astronomers were able to see Mars’ brightness and position changes in the sky. With the invention of powerful telescopes, scientists were able to see the surface of Mars for the first time. Today, we send robotic missions to Mars to study its surface. The distinct red color was observed by stargazers throughout history. It was given its name by the Romans in honor of their god of war. It is still a favorite of science fiction writers as the most favorable place in the Solar System (other than Earth) for human habitation and the best candidate for harboring extraterrestrial life. Astronomers thought they saw straight lines crisscrossing its surface. This led to the popular belief that irrigation canals on the planet had been constructed by intelligent beings. In 1938, when Orson Wells broadcasted a radio drama based on the science fiction classic War of the Worlds by H.G. Wells, enough people believed in the tale of invading Martians to cause a near panic.

2. Mars vs. Earth
Interest in Mars began long before we were able to send spacecraft to the RED Planet…
What is earth’s nickname?
Name was given by the Romans in honor of their God of war.
Early astronomers were able to see Mars’ brightness and position changes, but telescopes allowed us to see the surface of Mars.
It is still a favorite of science fiction writers as the most favorable place in the solar system for human habitation…MARTIANS!
Orson Wells – War of the Worlds – 1938 – Radio drama that caused a near panic.

3. Atmosphere
This oblique image taken by the Viking orbiter spacecraft shows a thin band of the Martian atmosphere. You would have to wear a space suit to provide air and to protect you from the Sun’s rays because the planet’s thin atmosphere does not block harmful solar radiation. Your space suit would also protect you from the bitter cold; temps rarely climb above freezing and they can plummet to 200 degrees below 0. You would need to bring water with you.
The atmosphere is composed primarily of carbon dioxide with small amounts of other gases. Martian air contains only about 1/1,000 as much water as our air, but even this small amount can condense out, forming clouds that ride high in the atmosphere or swirl around the slopes of towering volcanoes. Local patches of early morning fog can form in valleys. At the Viking Lander 2 site, a thin layer of water frost covered the ground each winter.

4. Mars Atmosphere Thin atmosphere
Need a space suit to protect you from the sun’s rays … solar radiation
Extremely cold – rarely climbs above freezing and can plummet to 200 degrees below 0.
Atmosphere is composed primarily of carbon dioxide.
Air contains only 1/1,000 as much water as our air, but it does condense out forming clouds that rise high in the sky.

5. Mars from Earth
The surface is red because the iron in the surface material (rocks, dust) has been oxidized. Huge dust storms sweep over the plains, darkening the entire planet for days. This NASA Hubble Space Telescope view of the planet Mars is the clearest picture ever taken from Earth, surpassed only by close-up shots sent back by visiting space probes. The picture was taken on February 25, 1995, when Mars was at a distance of approximately 65 million miles (103 million km) from Earth. Mars gets so cold that even the carbon dioxide gas freezes. Mars has permanent ice caps at both poles composed mostly of solid carbon dioxide (dry ice). Because it is spring in this picture in the Mars' northern hemisphere, much of the carbon dioxide frost around the permanent water-ice cap has sublimated (changes from a solid to a gas), and the cap has receded to its core of solid water-ice several hundred miles across. The abundance of wispy white clouds indicates that the atmosphere is cooler than seen by visiting space probes in the 1970s. Morning clouds appear along the planet's western (left) limb. These form overnight when Martian temperatures plunge and water in the atmosphere freezes out to form ice-crystal clouds.

6. Mars from Earth The previous picture was taken Feb 25, 1995.
Mars was 65 million miles from earth.
Gets so cold that the carbon dioxide freezes.
Permanent ice caps at both poles.

7. Earth vs. Mars 3rd rock from the sun! 4th rock from the sun!
(farther from the sun)
Year – 365 days
Year – Earth days
(orbits the sun slower)
Day – 24 hours
Day – 24.6 Earth hours
(rotates on axis slower)
Size – 12,756 km
Size – 6,794 km
Temp °F - 136°F
Temp °F - 75°F
Satellites – 1 Moon
Satellites – 2 Moons
Eccentricity – .017
Eccentricity – .093
Rotational axis tilt – 23.5 °
Rotational axis tilt – 25°

8. Extreme Temperatures at Mar’s Equator
32º F
70º F

9. Mar’s Gravity – 1/3 of Earth’s

10. Image from the Viking 2 Lander – Notice the frost on the ground.
Surface of Mars
The surface is covered with red rock and soil. This color is due to the oxidation (rusting) of iron in the rocks and soils. The pink color of the sky is caused by fine red dust that is suspended in the Martian atmosphere.
Image from the Viking 2 Lander – Notice the frost on the ground.

11. Mars is similar to the Moon
Similar to the moon, Mars’ southern hemisphere is covered with thousands of impact craters. In contrast, most of the northern hemishphere consists of planis which are much younger, lower in elevation. An abrupt elevation change of several kilometers seems to occur at the boundary of the hemispheres. The reasons for this global dichotomy and abrupt boundary are unknown although some speculate that they are due to a very large impact shortly after Mars’ accretion.
Image from the heavily cratered Southern hemisphere.

12. Impact Crater

13. Olympus Mons – Volcano!
Olympus Mons is the largest known volcano in the entire solar system! It rises 15 miles and stretches 300 miles across.
Giant shield volcano 550 km across (about the size of the state of Colorado.)

14. Compare Mountains

15. Mars Seasons North Days South
summer 183 winter fall 147 spring winter 158 summer spring 199 fall
Seasons on Mars occur the same way they do on Earth. Mars’ axis is tilted about 25 degrees. When the northern hemisphere is facing the sun, it is summer in the orth. This occurs when Mars is at its farthest from the sun in its orbit. The orbit of Mars is not nearly circular as is Earth’s. In fact, it is quite elliptical and the sun is not in the center of the ellipse. Information retrieved from the ill-fated Mars Observer Mission in 1993 reveals that the eccentricity (lack of being circular) of Mars orbits results in seasons that are not of equal length. The distance from the sun as well as the tilt of the axis are factors in the seasons.
Mars rotational axis tilts towards the sun at angle of 25°. Earth has a similar tilt of 23.5°. This tilt causes the seasons on both planets. The eccentricity (lack of being circular) of Mars results in seasons of unequal length.

16. Credits
V01AQTOH.pdf – in pdsmovies folder