Astronomy Exam 2 Flashcards
-Innermost planet
-Smallest planet
-no atmosphere
-cratered highlands
-vast, smooth terrains
-very dense
-revolves quickly
-rotates slowly
-close to the Sun
-weak magnetic field
-Much like the Moon
-3 rotations for every 2 revolutions
-3 days on this planet = 2 years on Earth
-Closest planet to the Earth
Mercury
-Second to the moon in brilliance
-Similar to Earth in size, density, location in the solar system
-shrouded in thick clouds
-impenetrable by visible light
-atmosphere is 97% carbon dioxide
-surface atmospheric pressure is 90 times that of Earth’s
-second largest terrestrial planet
-80% of the surface is subdued plains that are mantled by volcanic flows
-low density of impact craters
-tectonic deformation must have been active during the recent geological past
-thousands of volcanic structures
Venus
-called the “red planet”
-the atmosphere is 1% as dense as Earth’s, primarily carbon dioxide, cold polar temps, polar caps of ice water, covered by a thin layer of frozen carbon dioxide, extensive dust storms with winds up to 271 (170 miles) kilometers per hour
-Surface has numerous volcanoes, less abundant impact craters, tectonically dead, several canyons, some larger than the Grand canyon, Valles Marineras is the largest canyon. Stream drainage patterns are found in some valleys, no bodies of surface water on the planet, possible origins are past rainfalls and surface material collapses as the subsurface ice melts.
-moons, two moons are Phobos and Deimos, they are captured asteroids.
Mars
-Largest planet
-very massive, 2.5 times more massive than the combined mass of the planets, satellites, and asteroids; if it had been 10 times larger, it would have been a small star
-rapid rotation; slightly less than 10 hours; slightly bulged equatorial region
-banded appearance; multicolored; bands are aligned parallel to the equator; generated by wind systems
-great red spot; in planet’s southern hemisphere; counterclockwise rotating cyclonic storm
-moons; at least 84 moons; four largest were discovered by Galileo; Callisto- outermost moon, Europa- smallest moon, Ganymede- largest jovian satellite, Io- innermost and volcanically active
Jupiter
-similar to Jupiter in its atmosphere, composition, internal structure
-Rings are the most prominent feature, discovered by Galileo in 1610, complex, composed of small particles (moonlets) that orbit the planet, most rings fall into one of two categories based on particle density, thought to be debris ejected from moons, origin is still being debated
-Other features are a dynamic atmosphere, large cyclonic storms similar to Jupiter’s Great Red Spot, 80 named moons
-Titan is the largest Saturnian moon, second largest moon (after Jupiter’s Ganymede) in the solar system, has a substantial atmosphere and lakes of methane
-Enceladus, geological activity, vents H2O vapor from geysers from its southern pole
Saturn
-nearly a twin with Neptune
-Roates on “its side”
-Rings
-27 large moons have varied terrains
Uranus
-dynamic atmosphere, one of the windiest places in the solar system, Great Dark Spot, White, cirrus-like clouds above the main cloud deck
-13 satellites
-composition- liquid nitrogen and hydrogen
-Triton-largest moon of this planet, lowest temps in the solar system, volcanic activity-cryovolcanism
Neptune
-Most lie between Mars and Jupiter in asteroid belt
-Small bodies (largest Ceres)
-some have very eccentric orbits
-origin is uncertain
Asteroids
-large dirty snowballs
-composition is frozen gases, rocky metallic materials
-Frozen gases vaporize when near the Sun, produces a glowing head called the coma, some may develop a tail that points away from Sun due to radiation presses and solar wind
Comet
-called this when they enter Earth’s atmosphere
-showers occur when Earth encounters a swarm of meteoroids associated with a comet’s path
-are referred to as meteorites when they are found on Earth
-Iron and stony meteorites
-carbonaceous chondrites- mixture of stony-iron meteorites
meteoroids
-not visible with the naked eye, discvoered in 1930, dwarf planet, its moon (Charon) was discovered in 1978, ave. temp is -210C
Pluto
-the solar nebula consisted of hydrogen and helium in addition to microscopic dust grains
-a disturbance caused the solar nebula to slowly collapse and rotate
-the solar nebula assumed a flat, disk shape with the protosun at the center
-inner planets began to form from metallic and rocky substances
-larger outer planets began forming from fragments of ice
Nebular Theory
rotates almost on its side
Uranus
rotates opposite the other planets
venus
Measuring the towards and away movement of a host star as a planet makes its orbit
Doppler Effect
observations of a star dimming as a planet transits between the star and the observer.
Planetary Transits
-Done so by looking at their mass and their distance from their host star in AUs
-Compare their mass to that of Jupiter
Earth-like- mass would be similar to that of the Earth
Super-Earths
Neptunes
Jupiters
Hot-Jupiters
Brown Dwarfs
Types of Exoplanets
the zone around a star in which water can exist in a liquid phase, potentially in all three phases
The habitable zone
-One of the 400 billion stars that make up the Milky Way Galaxy
-only star close enough to allow the surface features to be studied
-an average star
- made mostly of hydrogen and helium
-structure that can be divided into four parts- solar interior, visible surface or photosphere, chromosphere, corona
The Sun
-“Sphere of Light”
-sun’s surface is actually a layer of incandescent gas less than 500 kilometers thick
-grainy texture made up of many small, bright markings, called granules, produced by convection
-most of the elements found on Earth also occur on the Sun
-temperature averages approximately 6000 K (10,000 F)
Photosphere
-just above the photosphere
-lowermost atmosphere
-Relatively thin, hot layer of incandescent gases a few thousand kilometers in thickness
-top contains numerous spicules-narrow jets of rising material
Chromosphere
-outermost portion of the solar atmosphere
-Very tenuous
-Ionized gases escape from the outer fringe and produce the solar wind
-Temperature at the top exceeds 1 million K
-Solar wind and the Sun’s magnetic field make a bubble called the heliosphere that extends past Pluto
Corona
-Sunspots
-plages
-prominences
-Flares
Solar Features
-on the solar surface
-dark center, the umbra, surrounded by a lighter region, the penumbra
-dark color is due to a cooler temperature (1500 K less than the solar surface)
-follow an 11-year cycle
-large spots are strongly magnetized
-pairs have opposite magnetic poles
Sunspots
-Bright centers of solar activity
-occur above sunspot clusters
Plages
-huge arching cloudlike structures that extend into the corona
-condensations of material in the corona
-large twisted shape
Prominences
-explosive events that normally last an hour or so
-sudden brightening above a sunspot cluster
-release enormous quantities of energy
-eject particles that reach Earth in about one day and interact with the atmosphere to cause auroras (the northern and southern lights)
Flares
-nuclear reaction that produces the Sun’s energy
-four hydrogen nuclei are converted into a helium nuclei
-matter is converted to energy
-600 million tons of hydrogen is consumed each second
-Sun has enough fuel to last another five billion years
Proton-proton reaction
The average distance from the Earth to the Sun, or 1 AU is ~ how many miles?
93,000,000
The two major elements that make up the sun are?
Hydrogen & Helium
What class of star is our Sun?
Yellow dewarf
What is the Sun’s volume compared to that of the Earth’s?
1,000,000
What is the temperature of the surface of the sun?
10,000 F
How long has the Sun been burning?
~5 billion years
At what temperature does Hydrogen to Helium fusion begin in the core of the Sun?
18,000,000 F
What is the rate of fusion in the core of the sun?
600 mill tons H to 595 mill tons He per second
What two types of planets are found in the solar system?
Terrestrial & Jovian
When a planets exists at a distance from it’s sun that water exists in all three phases, it is said to exist in the what?
Goldilocks Zone
How many magnetic poles exist on the sun?
1-10 Million
Due to differential rotation, the equator of the sun rotates how often?
35 Days
Solar maximum polarity occurs how often?
11 years
How often due we experience a total solar eclipse on Earth?
~1.5 years
What is the ultimate fate of the Sun?
White Dewarf
What is one possible explanation for the high temperatures found in the corona?
Sound Waves
How do the atmospheres of the Moon and Mercury compare?
Neither body has a permanent true atmosphere.
Earth’s magnetic field:
prevents charged particles in the solar wind from reaching the surface
Earth and Venus are often called sister planets; in which ways are they most alike?
size, density, and surface gravity
The main problem spacecraft have encountered in landing on Venus is:
the extremely high temperatures
The largest shield volcano yet discovered is:
Olympus Mons on Mars.
The lunar highlands are
more rugged, heavily cratered, and older than the lunar mare.
The presence of a magnetic field is a good indication that:
we have a liquid metal outer core, spinning rapidly as we rotate.
What gas is the primary constituent of our atmosphere?
nitrogen