# HHS Earth Science 1st sem exam

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### How old is our universe?

13.6 billion years

### How old is our planet?

4.5 billion years

### Why do the positions of the stars appear to change during the night?

B/c the Earth is rotating on axis

### Why do the positions of the stars appear to change during the year?

B/c the Earth is revolving around the sun

### How does the Foucault Pendulum provide evidence of the rotation of the Earth on its axis?

The path of the pendelum appears to change, but is the movement of the floor as the Earth rotates

### How do seasons differ between the northern and southern hemispheres?

Opposite (when it is summer in north, it is winter in south)

### When does the northern hemisphere have the greatest number of daylight hours?

During summer solstice

### Differentiate between rotation and revoloution.

Rotation is spin around an axis
Revolution is to move around another object

### Differentiate between solstices and equinoxes

A solstice is when the sun is as far north or as far south as possible
An equinox is when the sun appears to cross the equator (only occurs twice a year)

### Why does the earth have seasons?

Because it is tilted on its axis (tilted towards the sun is summer, away is winter)

### What is a light-year?

distance light travels in one year

### What is the Big Bang?

Theory that all matter and energy in the universe was compressed into a small volume that exploded

### What is a singularity?

The point at which all matter was condensed before the Big Bang

### Explain why only one side of the moon is visible from the Earth.

The moon revolves and rotates at the same rate.

### Perihelion

earth's closest point to the sun

### Aphelion

earth's farthest point to the sun

### Perigee

a satellite's closest point to the earth

### Apogee

a satellite's farthest point to the earth

### Describe how time zones are divided.

Earth divided into 24 time zones. Each one covers 15 degrees longitude. Earth is divided so the sunrise and sunset occur approximately at the same local time in each zone.

### Why do we have day light savings time?

Daylight savings time was started so we would have more "walking" daylight hours

### Define Inertia

The tendancy of an object to maintain its state of motion

### How does the electromagnetic radiation emitted by a star change when it is moving away from us? Toward us?

As it moves away it appears red, as it moves toward us it appears blue

### What is a galaxy?

A collection of stars, dust, and gas that is held together by gravity

Spiral

### Describe the relationship between universe, galaxy and solar system.

Multiple solar systems are held within a galaxy. All galaxies make up the universe.

### What is the difference between astronomy and cosmology?

Astronomy is study of universe.
Cosmology is study of how universe began.

### What is a quasar?

A luminous object/region that produces at a high rate

### What does the energy emitted by a quasar suggest?

A giant black hole in the center of of the universe

### What makes up most of the universe?

Dark energy makes up about 73 percent

### What is the supporting evidence that dark energy exists?

The rate of the expansion of the universe is accelerating.

### What is gravity?

The force of attraction that exists between all mass

### Describe the motion of circumpolar stars in the Northern Hemisphere.

They appear to circle around the North Star. They are always visible because they n ever "drop" below the horizon

### What is important about Hubble's discovery that there is a red shift in the spectra of galaxies?

Provided evidence of the Big Bang.

### What are constellations?

Groups of stars in recognizable patterns

### Describe the Doppler Effect?

The observed change in frequency of a wave when either the source is moving or the observer is moving.

Distance to star

### What is an irregular galaxy?

A galaxy that has no particular shape

### What is an elliptical galaxy?

A galaxy that has extremely bright stars in the center.

### What is a spiral galaxy?

A galaxy that has a nucleus of bright stars and flattened arms that spiral around the center.

Radiation uniformly detected from every direction in space.

### What is a pulsar?

A rapidly spinning neutron star that emits pulses of radio and optical energy

### How are space-based telescopes better than Earth based telescopes?

They do not have to account for atmospheric turbulence

### What milestone of the US space program occurred in 1969?

First man on moon

### What is a planet?

A celestial object that orbits a sun

### What is an exoplanet?

Planets that are outside of our local solar system

### What is an asteroid?

A small rocky object that orbits the sun

### Where do metereoroids come from?

They are pieces of matter that become detached from passing comets or from the collisions between asteroids.

### What are meteoroids made from?

Stony, iron, or stony-iron

### What is the difference between a meteoroid, meteor, and a meteorite?

Meteoroids are in space. The streak of light that results when a meteoroid enters an atmosphere is a meteor. Meteorites strike the planetary surface without burning up.

### Explain why Pluto is no longer considered a major planet.

It has a "tilted" orbit around the sun. Its moon Charon is almost half its size. Many objects that are similar to Pluto in size.

### Explain why Venus has a runaway greenhouse effect.

It has an atmosphere made primarily of CO2.

### Explain why Mercury has such a large daily change in temperature.

It has little to no atmosphere. The daylight side heats up quickly due its proximity to the sun. At night the temperature drops quickly.

### What is a moon?

A natural satellite that orbits a planet.

### What is the process of differentiation?

The process early in a moon's or planets development in which atmospheres form.

### Compare solar system models of Aristotle, Ptolemy and Copernicus.

Aristotle-heavens were made of 55 concentric crystal spheres. Stars and planets were attached. Earth was center.
Ptolemy-planets were attached to circles on the concentric layers.
Copernicus-sun was center of universe

### Explain the relationship between the average distance of a planet from the sun and the planet's orbital period.

The farther the planet from the sun, the longer it takes the plant to complete its orbit.

### Define eccentricity.

It describes how elliptical the orbit of a planet or moon is.

### Define orbital period.

The length of time it takes a planet to orbit the sun.

### Explain the Law of periods.

The square of a planet's period equals the cube of its average distance to the sun.

### Explain Kepler's 1st law of Planetary motion.

All planets orbits of the sun are ellipses.

### Contrast the structure of inner planets to the outer planets.

Inner planets are small and rocky with 0 to 2 moons. Outer planets are large gas giants with many moons. All outer planets have rings.

### What are impact craters caused by?

Large objects hitting the surface.

### What is the Kuper Belt?

Region of space beyond the orbit of Neptune that contains small bodies made mostly of ice.

### Why is Earth capable of sustaining life?

It has water; maintains moderate surface temps; has an ozone layer protecting Earth from UV radiation

### Describe the process of outgassing.

Volcanic activity released large amounts of gas. The ozone formed from remaining oxygen molecules. Ozone collected in the high atmospheric layer around the Earth.

### How did the oceans become salty.

Over millions of years, rainwater fell to Earth and dissolved some of the rocks on land, carrying dissolved minerals into the oceans. As water cycled back into the atmosphere through evaporation some of these chemicals combined to form salts.

### Explain why Earth's early atmosphere lost most of its H and He.

Earth did not have enough gravity to hold on to the lighter gases in its atmosphere.

Mars

### What separates the inner planets from the outer planets?

The main asteroid belt

### What is a solar nebula?

A rotating cloud of gas and dust from which the sun and planets form.

the sun

### How are protoplanets and planetesimals related to planets?

Planetesimals are swirling dense regions within the nebular. Planetesimals collide to from protoplanets. Protoplanets form planets.

### Why does it appear as though planets that orbit more slowly than Earth are moving backward?

Have larger orbits than Earth. The Earth is "lapping them" in the movement around the sun.

### Structure of our moon (Luna).

craters; rills (long deep channels); ridges; mare (dark smooth areas); regolith (loose dirt); no atmosphere; 1/6 gravity of earth; interior is less dense than earth

### How are Jupiter's Great Red Spot and Neptune's Great Dark Spot similar?

They are both large storms on the surface

Asteroids

Coolest-red
Hottest-blue

### How do scientists determine the composition and temperature of stars.

From the light emitted from the star

### What is a pulsar?

A spinning neutron star that is releasing large amounts of electromagnetic radiation

### Durint the main sequence stage, how is energy generated in a star's core?

Energy is generated by nuclear fusion.

### Describe the main sequence of stars.

Main sequence stars are stars that are actively converting hydrogen to helium in the core

10 billion years

### What elements make up most of the Sun's mass?

Hydrogen and helium

### Describe the process of nuclear fusion.

2 H nuclei collide to combine to form 1 helium nuclei.

### What has to happen before nuclear fusion can occur in a star?

Pressure and temperature must be high

### How does a star maintain equilibrium?

When the inward force of gravity is balanced by the outward pressure produced by the expanding gases.

### How does E=mc2 relate to the process of nuclear fusion?

It explains why large amounts of energy is released during the process

### What is a nova? Supernova?

They are exploding stars. Occurs after a star has stopped fusing H to He in the core. The star begins to collapse b/c gravity is greater than the outward pressure.

### What are binary stars?

2 stars which revolve/move about the same gravitational center

### What is apparent magnitude of a star?

How bright a star appears from Earth

### What is absolute magnitude of a star?

The stars real brightness

### How do stars with a negative number for their apparent magnitudes compare to stars with a positive number for their apparent magnitude?

Stars with negative apparent magnitudes appear brighter.

### List several benefits of the space program.

Studying how stars shine may help us develop new energy sources; protecting us from collision with asteroids; more accurate weather predictions

### Explain purpose of Mars500 project.

To determine the psychological impact long term isolation would affect humans.

### Why are humans the "weak link" in space travel?

B/c we have to sleep, eat, and discharge waste (poop and pee).

### Why do we need to send humans to Mars?

To maintain public interest in space programs, and we want to find out if we are alone in the universe.

### Mercury

no moons; closest to sun little to no atmosphere; no moons

### Venus

runaway greenhouse effect; atmosphere has a lot of carbon dioxide; mountians, volcanoes

### Earth

1 moon proper conditions for life; moderate temps

### Mars

2 moons; Deimos and Phobos; seasons like the earth; may have water under surface

### Jupiter

Largest planet; single think ring; Great red spot; 60 moons

### Saturn

least dense planet; most moons are made of ice; ring system is complex

### Neptune

blue color indicates a lot of methane; axis of rotation is almost parallel to its plane of orbit; Gread dark spot

### Pluto

made of frozen methane, rock and ice; relcassified as Dwarf planet in 2006

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