exam 2 Flashcards by cassidy scanlan

Which 2 planets are our closest neighbor planets?

Venus and Mars

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What is the atmosphere of Venus like?

Very Thick
- pressure and temperature are very high (850°)
- chemical composition is poisonous to humans

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What is the atmosphere of Mars like?

Very Thin
- pressure at its surface is less than 1% that of Earth
- temperatures can range from 70° to -225°

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Which planet (Venus or Mars) has been easier to research and why?

Mars
- The temperature conditions allow robotic missions to land and survive for long periods of time

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Why is Venus the brightest object in the sky?

its closeness to the Sun and Earth
- highly reflective layer of clouds

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Why can we not view the face of Venus?

it is covered by dense clouds making it impossible to directly observe its surface

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How are Radio Waves emitted / how do they work?

emitted by the radar toward the planet and they then penetrate the clouds and reflect on the surface
- their reflection gives information about the altitude and roughness of the surface

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Which planet approaches Earth closer than any other planet?

Venus

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What is the surface of Mars like?

dry and cold, bright polar ice caps, heavily cratered highland terrain, volcanoes

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How have scientists determined the rotational period of Mars?

by watching the motion of permanent surface markings over a long period of time

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How long is 1 day on Mars? (rotation period)

24 hrs and 37 mins

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What is the rotational axis of Mars? (tilt)

Mars has a tilt of about 25° (similar to Earth’s)
- similar seasons

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How have scientists determined the rotational period of Venus, being that the surface isn’t visible?

by bouncing radar signals off the planet

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How long is 1 day on Venus? (rotation period)
How long is 1 year on Venus?
(how long it takes Venus to orbit the Sun)

(1 day) 243 days

(1 year) 225 days

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Which way do planets normally rotate?

West to East
- counterclockwise

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Which way does Venus rotate on its axis?

East to West
- clockwise
- “retrograde” / backwards

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Describe the surface of Venus

lowland lava plains, many geologic features (volcanos, mountains, and large impact craters)
- basalts

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What is the 1st and 2nd most abundant gases on Venus and Mars?

carbon dioxide
- nitrogen

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What makes Venus so hot?

The greenhouse effect

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Greenhouse Effect

greenhouse gases trap heat from the sun, preventing it from escaping back into space and thus warming the planet’s surface

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Why does the Greenhouse Effect affect Venus more than Earth?

Venus has around 1 million times more carbon dioxide than Earth (CO2)

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Describe the evidence for the presence of water in the past history of Mars

The climate on Mars used to be warmer with a thicker atmosphere (which would allow water to be liquid on the surface)
- Runoff Channels, Outflow Channels, Smaller Gullies

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Runoff Channels

small twisting channels that look like have been formed from runoff of ancient storms

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Outflow Channels

large, long, and wide channels that are carved by massive floods of water

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Smaller Gullies

located on steep slopes - very young channels like look like dark streaks

What does Mars not have?

Ozone Layer

Why did Mars lose atmospheric gases more easily and quickly than other planets?

- Low gravity - Small planet

What are the 4 giant (Jovian) planets in our solar system?

Jupiter, Saturn, Uranus, and Neptune - they hold most of the mass in our system

What 3 materials are giant planets made of?

Gases (hydrogen and helium), Rocks, Ice

The chemistry for all 4 giant planet atmospheres is dominated by _____

Hydrogen

The giant planets are very far from the Sun - (True/False)

True

Which planet has the shortest day?

Jupiter (10hrs)

Why do Earth and Mars have seasons?

Because their "spin axes" are tilted relative to the orbital plane of the solar system

What is the spin axis tilt of Uranus?

98° - orbits on its side - creates dramatic seasons

Which of the 4 giant planets has no seasons?

Jupiter

What are the interiors of Jupiter and Saturn primarily composed of?

hydrogen and helium

What does "Saturn is still differentiating" mean?

Letting lighter material rise and heavier material fall

Which giant planet has the largest internal energy source?

Jupiter

Uranus and Neptune have lower energy sources than Jupiter and Saturn - (True/False)

True

What are magnetic fields generated by?

Electric currents in the planet's rapidly spinning interior

Define magnetospheres

regions around the planet where the planet's own magnetic field dominates over the general interplanetary magnetic field - largest features

Jovian (giant) planets have solid surfaces - (True/False)

False

The primary clouds seen around Jovian (giant) planets are composed of what?

frozen ammonia crystals

Within the tropospheres of Jovian (giant) planets, the temperature and pressure both increase with depth - (True/False)

True

What are Uranus and Neptune's upper clouds composed of?

methane

How do we track wind speeds and the circulation of atmospheres on Jovian planets?

by observing changing cloud patterns

Giant planets spin faster than terrestrial planets - (True/False)

True

Deep convection currents of rising hot air and falling cooler air circulate throughout the atmospheres of Jovian planets in a vertical direction - (True/False)

True

What is convection?

A process in which liquids, heated from underneath, have regions where hot material rises and cooler material descends

Giant Molecular Clouds

birthplace of stars - a massive, dense cloud of gas and dust in space

T Tauri Stars

end of the stars formation phase (less than 10 million years old) - about to fuse hydrogen in their core - circumstellar disks / stellar winds

Herbig-Haro (HH) Object

high velocity jets slamming in - newborn star

Cloud clumps

large substructures of molecular clouds that occur before star clusters

Cloud core

the densest parts of molecular clouds where stars form

The brightness of a star indicates...

the relative concentration of dust - more dust means more radiation

Define exoplanet

a planet outside our solar system

Planets and their host star

both the planet and the star revolve around their *common center of mass*

Doppler Effect

detects a slight "wobble" in a star's motion caused by the gravitational pull of a planet orbiting it - allows us to find the minimum mass of a planet - provided the first concrete evidence that the universe is expanding

Define radial velocity

motion towards or away from us

Explain how the environment of a molecular cloud enables the formation of stars.

A molecular cloud provides a dense, cold environment where gravity can overcome internal pressure, causing the gas and dust within the cloud to collapse and form protostars

What planets emit more infrared light because they have more internal energy?

young giant planets

What is responsible for the discovery of most exoplanets?

The Kepler Telescope

The most common planet size are those called...

"Super-Earths" & "Mini-Neptunes"

Define "habitable zone"

the distance from the star where we calculate the surface temperatures would be consistent with liquid water

Luminosity

the total amount of energy at all wavelengths that it emits per second - total energy output

Brightness

the amount of a star's energy that reaches a given area

Stars emit the same amount of energy in every direction in space - (True/False)

True

Define photometry

the process of measuring the apparent brightness of stars

The brightest stars are usually referred to as what?

first-magnitude stars

Define the magnitude scale

Used to measure the brightness of a star - the brightest objects have the SMALLEST number and the faintest objects have the LARGEST numbers - backwards scale

Why are stars different colors?

Because they do not all have identical temperatures

Blue colors

additional radiation in the ultraviolet - dominate the visible light output of very hot stars

Red colors

more radiation coming off in the infrared - cool stars

Color does not depend on the distance of an object (color would not change) - (True/False)

True

What is the primary reason why stellar spectra look different?

the stars have different temps

Spectral classes are a measure of a star's ____?

surface temp.

There are 7 spectral classes from _____ to ______?

Hottest to coldest - O. B, A, F, G, K, and M

Spectra classes L, T, and Y

brown dwarfs - objects cooler than M9 type stars

Brown dwarfs

object that is between a planet and a star

What is the difference between a Low-Mass Brown Dwarf and a High-Mass Planet?

Deuterium Fusion - Brown dwarfs can't sustain regular hydrogen fusion, but they are capable of deuterium fusion

exam 2 Flashcards

(80 cards)