Astronomy Exam 2 Flashcards by Mary Baalman

-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

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-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

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-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

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-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

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-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

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-nearly a twin with Neptune
-Roates on “its side”
-Rings
-27 large moons have varied terrains

Uranus

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-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

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-Most lie between Mars and Jupiter in asteroid belt
-Small bodies (largest Ceres)
-some have very eccentric orbits
-origin is uncertain

Asteroids

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-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

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-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

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-not visible with the naked eye, discvoered in 1930, dwarf planet, its moon (Charon) was discovered in 1978, ave. temp is -210C

Pluto

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-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

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rotates almost on its side

Uranus

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rotates opposite the other planets

venus

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Measuring the towards and away movement of a host star as a planet makes its orbit

Doppler Effect

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observations of a star dimming as a planet transits between the star and the observer.

Planetary Transits

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-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

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the zone around a star in which water can exist in a liquid phase, potentially in all three phases

The habitable zone

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-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

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-“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

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-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

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-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

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-Sunspots
-plages
-prominences
-Flares

Solar Features

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-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

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-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

Rank these magnetic fields, from weakest to strongest.

Venus, Mars, Mercury, Earth

Which body has the greatest gravitational pull on Earth?

the sun

Mercury's surface most resembles that of which other body?

moon

From the center outward, the correct order is:

solid metallic inner core, molten metal outer core, silicate mantle and crust.

The most striking valley in the solar system is:

Valles Marineris on Mars.

Why is it reasonable to conclude that the internal structure and evolution of Venus are basically Earthlike?

They have similar masses and sizes.

Mercury experiences extreme high and low temperatures between night and day because:

it has no true atmosphere to moderate temperatures over the globe.

The average rate of erosion on the Moon is far less than on Earth because:

the Moon lacks wind, water and an atmosphere.

What is the result of the greenhouse effect on the surface environment of Venus?

It has raised the surface temperature by hundreds of degrees Celsius.

The critical part of the atmosphere for protecting life on the ground from excessive ultraviolet radiation is the:

ozone layer

What is the main constituent of the atmosphere of Venus?

carbon dioxide

How long is a day on Mars

24 hours, 36 minutes

Mars's magnetic field is so weak because:

-its core contains less iron than our own. -its core may no longer be molten.

The atmospheric pressure on Venus:

is much higher than on Earth.

Which is the correct size order, from smallest to largest?

Mercury, Mars, Venus

Evidence of liquid water in Mars's distant past suggests that it had a substantial atmosphere compared to what it has presently. What happened to its water vapor?

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

The crust of the Earth is covered by about ________ water in the hydrosphere.

70%

Evidence of lava flows is common on the surface of Venus.

True

Valles Marineris is comparable in size to Earth’s Grand Canyon.

False

Mars has the largest volcanoes in the solar system.

True

The solid surface of Jupiter lies just below the cloud layers that are visible from Earth.

False

Europa may have liquid water below its frozen surface.

True

Although often referred to as a gaseous planet, Jupiter is mostly liquid in its interior

True

Neptune probably does not have a rocky core.

False

The magnetic fields of Uranus and Neptune are highly tilted relative to their rotation axes and offset from the planets’ centers.

True

Mercury’s large overall density suggests that the planet

Has a large metal core

Compared with Earth, Venus has a level of plate tectonic activity that is

virtually nonexistent

In terms of area, the extinct Martian volcano Olympus Mons is about the size of

Colorado

The main constituent of Jupiter’s atmosphere is

hydrogen

Compared to Earth, Saturn’s core is roughly

10x more massive

Compared with Uranus, the planet Neptune is

roughly the same size

Jupiter’s magnetosphere extends about

5 AU

Saturn’s ring particles are made up mainly of water ice.

True

Saturn’s rings lie within the planet’s Roche limit.

true

Two small shepherd satellites are responsible for the unusually complex form of Saturn’s F ring.

true

Titan’s surface is obscured by clouds of ammonia ice.

False

Triton’s orbit is unusual because it is retrograde.

true

Asteroids were recently formed by the collision and breakup of an object orbiting in the asteroid belt.

false

Asteroids were recently formed by the collision and breakup of an object orbiting in the asteroid belt.

false

Pluto was discovered via its gravitational effect on the orbit of Neptune.

false

Io’s surface appears very smooth because it

is continually resurfaced by volcanic activity

The Galilean moons of Jupiter are sometimes described as a miniature inner solar system because

the moons’ densities decrease with increasing distance from Jupiter;

The rings of Uranus are

narrow and dark

The solar system object most similar to Pluto is

triton

Trojan asteroids are located

behind and in front of Jupiter, sharing its orbit;

Most main-belt asteroids are about the size of

a small US city

Compared with the orbits of the short-period comets, the orbits of long-period comets

can come from all directions

Large Kuiper belt objects are not regarded as planets because

their masses are too low to clear other bodies from their orbital paths

The planets are much older than the Sun.

false

The solar system is of largely uniform composition.

false

The inner planets formed primarily by collisions and mergers of planetesimals.

true

Asteroids, meteoroids, and comets are remnants of the early solar system.

true

The nearest exoplanet lies thousands of light-years away.

false

Astronomers have no theoretical explanation for the “hot Jupiters” observed orbiting some other stars.

false

Super-Earths always orbit very close to their parent star.

false

Thousands of habitable, Earth-like exoplanets are currently known.

false

A model of the origin of planetary systems must be able to account for all of the following solar system features, except for

intelligent life

the temperature in the solar nebula at the location now at the center of the asteroid belt was

400 K

The solar system is differentiated because

only rocky and metallic particles could form close to the Sun.

The jovian planets formed

within a few million years of the formation of the Sun;

The number of confirmed exoplanets is

more than 1000;

most known extrasolar planets are

cool and massive

the habitable zone of a star twice as massive as the Sun

is about 5 AU thick;

A planet in the habitable zone (a) has living creatures on it;

is rocky, like Earth

The Sun is a rather normal star.

true

Nuclei are held together by the strong nuclear force.

true

The proton–proton chain releases energy because mass is created in the process.

false

The most abundant element in the Sun is hydrogen.

true

There are as many absorption lines in the solar spectrum as there are elements present in the Sun.

False

The density and temperature in the solar corona are much higher than in the photosphere.

False

Sunspots appear dark because they are hotter than the surrounding gas of the photosphere.

False

Flares are caused by magnetic disturbances in the lower atmosphere of the Sun.

True

Compared with Earth’s diameter, the Sun’s diameter is about

100 times larger

Overall, the Sun’s average density is roughly the same as that of

water

The Sun spins on its axis roughly once each

month

A typical solar granule is about the size of

a large US state

As we move to greater and greater distances above the solar photosphere, the temperature in the Sun’s atmosphere;

first decreases and then increases

The time between successive sunspot maxima is about

a decade

The primary source of the Sun’s energy is

fusion of light nuclei to make heavier ones

Neutrinos from the solar core

can turn into other particles before reaching Earth

Astronomy Exam 2 Flashcards

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