Astronomy Ch. 10 - Mars

Mars was closer to us than it has been in over 50,000 years.

opposition.

Mars was both at perihelion and opposition, creating the perfect viewing conditions from Earth.

because it is smaller, farther away and less reflective

its density

Mercury, Mars, Venus

24 hours, 36 minutes

It is almost identical to the Earth.

the orbit of Mars is significantly more elliptical.

the sons of Ares and Aphrodite

Mars' weather is driven by evaporation from the polar ice in its summer. Mars' orbit is more eccentric than our almost circular one. Mars' seas dried up long ago. Mars' axial tilt is slightly more than our 23.5 degrees. All of these contribute to the huge barometric changes that Mars experiences.

its bright polar caps.

highly cratered and eroded areas that are frequently covered and uncovered by dust

volcanic planes like the lunar maria.

the Valles Marineris has craters in and around it. the Grand Canyon was formed by water. the Valles Marineris has tectonic features surrounding it. the Valles Marineris is much larger than the Grand Canyon. all of the above

dust storms capable of covering the entire planet seasonal changes in the polar caps Both A and C are correct.

Hellas Basin of Mars.

rift valley.

Valles Marineris on Mars.

Olympus Mons on Mars.

The southern hemisphere is more heavily cratered.

shield volcanoes.

Vikings I and II.

Its thick crust can support larger peaks, and lower surface gravity does not pull them down as much as on Earth.

It sits above a hot spot in the planet's mantle.

Mars Global Surveyor

Vikings 1 and 2 in 1976.

Pathfinder.

the southern appears older, with more impact craters.

North America

The wind blows small dust particles, eroding the surface of Mars, erasing small impact craters faster than they can form.

Hellas.

suggests it is the youngest region on the planet.

enormous, as much as 100 times the flow rate of the Amazon River.

catastrophic but rare flooding

The atmosphere has frozen out into the polar ice caps and permafrost as Mars has cooled.

The iron in the surface rocks have been oxidized over time.

the few carbonate rock layers that would have formed on the bottoms of oceans.

"fluidized ejecta" craters.

We have confusing and uncertain results to date.

carbon dioxide.

they orbit at different distances from the Sun.

that its troposphere changes altitude.

Both are chiefly carbon dioxide, but at Mars it can freeze as dry ice.

great changes in the barometric pressure as the atmosphere freezes and sublimes. remarkable changes in size of the two dry ice polar caps. huge dust storms that can enshroud the planet's disk. changes in the dark features noted from Earth by telescopes long ago. All of these are correct.

Venus, Mars, Mercury, Earth

its core contains less iron than our own. it core may no longer be molten. Both B and C are probable.

two

Both are in retrograde orbits.

Their composition is significantly different from Mars and the terrestrial planets.

Runoff channels from old rivers and outflow channels from catastrophic flooding in the distant past. Recent mudflows down the sides of some canyons and crater walls suggest occasional eruptions of liquid water persist to this day, as imaged by the Global Surveyor. The Rovers in 2004 also found clear evidence of sedimentary rocks formed under water at both the landing sites, on opposite sides of the globe.

The major component of Mars' atmosphere, carbon dioxide, freezes out as dry ice every winter, forming a huge but very thin polar cap. But in the opposite hemisphere, that cap is subliming back into the atmosphere, creating a high pressure area above it. With the changing seasons, the atmosphere "flip-flops" from pole to pole, with great barometric pressure changes and hurricane force winds and dust storms observable from earth.

The lengths of the days are very similar, with Mars being 40 minutes longer. The axial tilts are also almost identical, with Mars tilted only .5 degrees more. The year, with Mars' much larger orbit, is over twice as long as ours, however.

Mars is small, and most of the time so distant from Earth that amateur telescopes have a problem seeing anything but an orange disk. But when the earth overtakes Mars every 2.2 years, Mars gets close enough to us to appear much larger and to show a good deal of surface features and atmospheric clouds, polar caps, and dust storms.