Ch. 15, 16, 17 Test

Explain the difference between brightness and luminosity?

Brightness: The amount of light that reaches Earth in one year. Luminosity: Total amount of light a star gives off.

What is the term for a full eclipse?

Umbra

What is the distance of the Earth from the Sun?

1 AU (Astronomical Unit), or 150 million kilometers.

How many years did it take for stars to begin to form after the Big Bang?

1 billion years.

How long does the main sequence stage of a sun like star normally last?

10 billion years.

About how many stars are in our galaxy?

200 billion

How many years do scientists believe are left before the Sun leaves the main sequence?

5 billion years.

How many major planets are their in the Solar System?

8

What does the word "planet" mean?

A Greek word meaning "wandering star"

What is a meteor?

A chunk of burning rock traveling through Earth's atmosphere.

What is bigger a supergiant star or a galaxy?

A galaxy.

What do scientists believe is at the center of the Milky Way galaxy?

A giant black hole.

What do scientists believe caused the extinction of the dinosaurs?

A large asteroid the hit Earth.

What is the definition of "planet"?

A massive object orbiting a star, like the Sun. A true planet has cleared the neighborhood around its orbit and has enough mass so that its gravity forms it into a spherical shape.

What is a meteorite?

A meteor that passes through Earth's atmosphere and strikes the ground.

All stars begin inside a huge cloud of dust and gas called what?

A nebula.

According to the Big Bang theory, how large was the universe before it exploded and expanded in all directions?

A single point smaller than an atom.

What is a planetary satellite?

A small body of matter that orbits a planet.

How is the spectrum for an element similar to a person's fingerprint?

All elements have different spectral lines.

The gas giant planets have atmospheres made of hydrogen and helium. What evidence does this give scientists about the formation of the planets?

All nine planets condensed out of the same cloud of interstellar material as the sun. The smaller planets could not hold onto the lighter gases and their exposed cores became the rocky planets. Under their atmospheres, the gas giants also have cores.

How do scientists believe heavier elements such as carbon and oxygen were created?

All the heavier elements are created by nuclear fusion inside the cores of stars.

What is the gap that cuts the solar system in two (between Mars and Jupiter)?

An asteroid belt.

What is an asteroid?

An object that orbits the Sun bit is too small to be considered a planet.

What makes up Saturn's rings?

Billions of chunks of rock and ice.

What are the three parts of a comet?

Coma, Nucleus, Tail

What are sunspots?

Cooler areas of the Sun.

Describe the three regions of the Sun.

Core: Where nuclear fusion happens, Radiation Zone: heat transfer through light energy, Convection Zone: heat transfer through hot gas.

What evidence for the Big Bang did the scientists Arno Penzias and Robert Wilson discover?

Cosmic background radiation.

What is the cause of Earth's seasons?

Earth's axis of rotation is in a 23 degree tilt.

What is Mercury most similar too.

Earth's moon

What important feature do Europa and Earth have in common?

Europa has an ocean of liquid water that might be warm enough to support life.

What force causes a nebula to form a protostar?

Gravity.

List the four variables astronomers use to classify stars.

Heat, Brightness, Size, and Color.

Fusion reactions that combine light elements release energy only until what element is created?

Helium.

What happens to the brightness of a star as you observe it from farther away?

It gets dimmer.

What can you tell about a star by looking at its color?

It's heat.

What are the gas planets?

Jupiter, Saturn, Uranus, and Neptune.

What are the outer planets?

Jupiter, Saturn, Uranus, and Neptune.

Is Saturn the only planet with rings?

No, Jupiter, Uranus, and Neptune have them too.

Which planet has the most extreme temperature variations?

Mercury

What are the inner planets?

Mercury, Venus, Earth, and Mars

What are the terrestrial planets?

Mercury, Venus, Earth, and Mars

Who first proposed that the planets orbit the Sun?

Nicolaus Copernicus

Is it probable that the Sun will become a supernova? Why?

No because it's core would have to be 1.4 times the mass of the Sun.

Why does a black hole appear black?

Nothing can escape from a black hole's gravity, even light, so a black hole appears black.

What is the basic process through which the Sun releases energy?

Nuclear fusion.

What are the three possible endings of the universe?

Open universe: galaxies will continue to expand until no energy left (end of the universe). Flat universe: expansion will be 0 after an infinite amount of time. Closed universe: expansion will halt, gravity will pull galaxies back together (blue shift!).

What shapes are the planets' orbits?

Orbits are mathematically ovals, but are closer to shifted circles.

What is the term for a partial eclipse?

Penumbra

Why is Neptune sometimes farther that the Sun than Pluto?

Pluto's orbit sometimes crosses Neptune's.

Who "explained" that the planets orbited Earth?

Ptolemy

List four galaxy shapes.

Spiral, Barred Spiral, Elliptical, Lenticular.

Why do stars with smaller masses burn longer than stars with larger masses?

Stars with bigger masses burn brighter and hotter and use up their hydrogen faster than low-mass stars.

What two important discoveries are credited to astronomer Edwin Hubble?

That the universe has more than one galaxies, and that galaxies are moving at increasing speed away from us the further they are (red shift) .

Why do scientists believe the surface of Mars may have contained liquid water in the past?

The Martian surface shows erosion and patterns of riverbeds similar to those formed by flowing water on Earth.

Which galaxy do we live in?

The Milky Way Galaxy.

What is the largest object in the Solar System?

The Sun

Which is bigger; a white dwarf star or the Sun?

The Sun

How does the size of the Sun compare with the size of other stars?

The Sun is average.

What is the definition of solar system?

The Sun, planets, and their moons, and other ovjects that are gravitationally bound to the Sun.

What is a light year?

The distance light travels in one year.

What is a supernova?

The explosion of a very large star.

What did Hubble discover about the relationship between a galaxy's location and speed?

The farther away a galaxy is, the faster it was moves away from Earth.

What is Newton's law of universal gravitation?

The force of gravity between objects depends on their masses and the distance between them.

What two discoveries did Galileo make that supported Copernicus' ideas?

The phases of Venus. Moons orbiting Jupiter

How did astronomers discover that the star Sirius was moving away from Earth?

The spectral lines for hydrogen were shifted closes towards the red side of the spectrum.

What happens when a sun like star runs out of hydrogen fuel in its core?

The star expands into a red giant.

What happens to the temperature and pressure in a protostar as it collapses?

They both become great enough to start nuclear fusion.

What planet has the slowest rotation?

Venus

What planet is closest to Earth in size, gravitational strength, and composition?

Venus

Which planet looks brightest in the sky.

Venus

What happened to the first space probe that landed on Venus?

Venus' atmosphere corroded it and destroyed it.

Which three planets rotate backwards?

Venus, Uranus, and Pluto

What can scientists learn about a star by studying the light it gives off?

What they are made out of and their temperatures.

What are the four types of stars categorized in a Hertzsprung-Russell diagram?

White Dwarf, Main Sequence, Red Giant, Blue Supergiant

Is a blue giant star likely to be older or younger than the Sun?

Younger.