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35 Cards in this Set

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average distance of Mars from the sun
227 million km (1.52 AU)or about half again as far from the sun as the earth. however, mars has a relatively large orbital eccentricity of...
mar's eccentricity
.093 so it varies with the earth by 42 km
venus's orbit
is circular at a distance of 108 km. "morning star" or "evening star"
Venus's appearance
about the same size and mass as earth. appears as a bright morning or evening star from eaerth. boring in a telescope--reflects about 70% of the sunlight. 3. cloud detail from spacecraft (ultraviolet) can't see surface in visible light. surface is shrouded with dense clouds that reflect about 70% of the sunlight that falls on them.
mars is red because of iron oxides in the planet's soil
best resolution attainable is 100 km...at this resolution there is no hint of topographic structure, except bright polar ice caps can be seen easily together with duky surface marking that sometimes change in outline and intesnity from season to season.
Schiaparelli
1877, when this italian astronomer announced that he could see long rfaint striaght lines on mars that he calle canale or channels, mistakenly tranlsated as canals....implying artificial origin
The Pioneer venus
took an ultraviolet picture that shows the upper atmosphere cloud structure that would be invisible at visible wavelenghts. note that there is not a glimpse of the planet's surface.
Percival Lowell
believed in aliens. studied chanels on mars. inspired "war of the worlds"
Astronomers have determined the rotation period of Mars with great accuracy by watching the motion of permanent surface markings, it's sideral day is
24 hrs 37 m 23 s, just a little longer than the rotation period of the earth. this high precision is not obtained by watching mars for a single rotation, but by noting how many turns it takes over a long periold of time.
rotational axis of mars has a tilt of about
25 degrees, similar to the tilt of the earth's axis. thus mars experiences seasons very much like those on earth. because of the longer martian year, each season lasts about six of our months.
finding venus's rotation period
its rotaation period can be found only by bouncing radar signals off the planet. the first radar observations of the planet's rotation were made in the early 1960's. later, topographical surface freatures were identified on the planet that showed up in the reflected radar signals.
so what is the rotation period of venus?
tprecisely determinded from the motion of such "radar features" across its disk is 243 days. even more suprising than how long venus takes to rotate is the fact that it spins in a backward or retrograde direction (east to west)
more on venus's rotation
sidereal rotation= --243 earth days, negative retrograde motion.

solar day= 117 days
rise W, sets int the E
may have been hit by something big
venus is in many ways the earth's twin, with a mass .82 times the mass of the earth and an almost identical density. the amount of geological activity is also relatively high, almost as high as on earth.
ON THE OTHER HAND, with a surface pressure nearly 100 times greater than ours, Venus' atmosphere is not at all like that of earth. the surface of venus is also remarkably hot, with a temp of 730 K (850 F)
average distance of Mars from the sun
227 million km (1.52 AU)or about half again as far from the sun as the earth. however, mars has a relatively large orbital eccentricity of...
mar's eccentricity
.093 so it varies with the earth by 42 km
venus's orbit
is circular at a distance of 108 km. "morning star" or "evening star"
Venus's appearance
about the same size and mass as earth. appears as a bright morning or evening star from eaerth. boring in a telescope--reflects about 70% of the sunlight. 3. cloud detail from spacecraft (ultraviolet) can't see surface in visible light. surface is shrouded with dense clouds that reflect about 70% of the sunlight that falls on them.
mars is red because of iron oxides in the planet's soil
best resolution attainable is 100 km...at this resolution there is no hint of topographic structure, except bright polar ice caps can be seen easily together with duky surface marking that sometimes change in outline and intesnity from season to season.
Schiaparelli
1877, when this italian astronomer announced that he could see long rfaint striaght lines on mars that he calle canale or channels, mistakenly tranlsated as canals....implying artificial origin
The Pioneer venus
took an ultraviolet picture that shows the upper atmosphere cloud structure that would be invisible at visible wavelenghts. note that there is not a glimpse of the planet's surface.
Percival Lowell
believed in aliens. studied chanels on mars. inspired "war of the worlds"
Astronomers have determined the rotation period of Mars with great accuracy by watching the motion of permanent surface markings, it's sideral day is
24 hrs 37 m 23 s, just a little longer than the rotation period of the earth. this high precision is not obtained by watching mars for a single rotation, but by noting how many turns it takes over a long periold of time.
rotational axis of mars has a tilt of about
25 degrees, similar to the tilt of the earth's axis. thus mars experiences seasons very much like those on earth. because of the longer martian year, each season lasts about six of our months.
finding venus's rotation period
its rotaation period can be found only by bouncing radar signals off the planet. the first radar observations of the planet's rotation were made in the early 1960's. later, topographical surface freatures were identified on the planet that showed up in the reflected radar signals.
so what is the rotation period of venus?
tprecisely determinded from the motion of such "radar features" across its disk is 243 days. even more suprising than how long venus takes to rotate is the fact that it spins in a backward or retrograde direction (east to west)
more on venus's rotation
sidereal rotation= --243 earth days, negative retrograde motion.

solar day= 117 days
rise W, sets int the E
may have been hit by something big
venus is in many ways the earth's twin, with a mass .82 times the mass of the earth and an almost identical density. the amount of geological activity is also relatively high, almost as high as on earth.
ON THE OTHER HAND, with a surface pressure nearly 100 times greater than ours, Venus' atmosphere is not at all like that of earth. the surface of venus is also remarkably hot, with a temp of 730 K (850 F)
Mars is rather small with a mass only .11 times the mass of the earth. it is larger than either the moon or mercryr. THIN ATMOSTPHERE
most fascinating thing, had a thick atmosphere and seas of liquid water, condtions we associate with life.
Geology of Venus
partly true that venus and earth have the kindof same geology. venus does not exhibit the same kind of plate tectonics as the earth, and we will see that its lack of erosion results in a very different surface appearance.
more spacecrafts have been sent to venus than to any other planet. . 1962 US Mariner 2 flyby ways the first, the SU launched most of the subsequent missions to venus. in 1970 Venera 7 became the first probe to land and broadcast data form the surface of venus. operated for 23 minutes.
since it's so cloudy, a radar instument is used to probe through the obscuring layer.
imaging radar! magellan was able to study the surface of venus at 100 m! are not actual photographs. bright featurs on these images are an indication of rough terrain, while darker regions are smooether.
venus=no erosion, water, or ice. wind speeds are very low. "dream planet"
75% of the surface of venus consists of lowland lava plains. . this planet never experienced plate tectonis. alothough CONVECTION (the rising of hot materials)
largest continent on venus=aphrodite
Maxwell mountains
Ishtar terea. near north pole. 11 KM below lowlands.
lowlands of venus are about 15% the age of lunar maria (500 million years)
biggest crater (MEAD) is 275 km in diameter.
in the lowland plains, volcanic erruptions are the principal way the surface of venus is renewed, with large flows of highly fluid lava destryoing old craters and generating a fresh surface. Largest individual volcano is called Sif Mons
tectonic features=on venus's lowland plains, tectonic forces have broken the lave surface to creat remarkable patterns of ridges and cracks. in a few places the crust has even torn apart to generate rift valleys.

subsurface bulges are common on venus, where they produce lare circular or oval features called coronae.