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Questions and Answers
What does the Big Bang Theory state?
What does the Big Bang Theory state?
Galaxies are moving toward each other as the universe expands.
Galaxies are moving toward each other as the universe expands.
False
What is a nebula?
What is a nebula?
A dense cloud-like collection of gas and dust in space.
Before the Big Bang, there was no ______, ______, or celestial bodies.
Before the Big Bang, there was no ______, ______, or celestial bodies.
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What type of galaxy has a pinwheel shape?
What type of galaxy has a pinwheel shape?
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Red shift indicates that a star is moving closer to Earth.
Red shift indicates that a star is moving closer to Earth.
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How do astronomers observe that the universe is expanding?
How do astronomers observe that the universe is expanding?
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Match the following galaxy shapes with their descriptions:
Match the following galaxy shapes with their descriptions:
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What is the primary difference between globular clusters and open clusters?
What is the primary difference between globular clusters and open clusters?
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Red stars have a surface temperature of about 6000°C.
Red stars have a surface temperature of about 6000°C.
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What phenomenon occurs when hydrogen atoms fuse into helium in a star?
What phenomenon occurs when hydrogen atoms fuse into helium in a star?
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The life of a low mass star can last up to _____ billion years.
The life of a low mass star can last up to _____ billion years.
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Match the star type with its expected lifespan:
Match the star type with its expected lifespan:
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What happens to a high mass star at the end of its life?
What happens to a high mass star at the end of its life?
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A star's color can indicate its composition and motion.
A star's color can indicate its composition and motion.
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What does the Doppler effect describe in relation to stars?
What does the Doppler effect describe in relation to stars?
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What phenomenon allows a black hole to have such a strong gravitational pull?
What phenomenon allows a black hole to have such a strong gravitational pull?
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All planets in the solar system have at least one moon.
All planets in the solar system have at least one moon.
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What are the inner planets of our solar system?
What are the inner planets of our solar system?
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The unit commonly used to describe distances in space is the ______.
The unit commonly used to describe distances in space is the ______.
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Match the following planets with their type:
Match the following planets with their type:
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What is the primary component of the Sun?
What is the primary component of the Sun?
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Light from the Sun takes about 8 minutes to reach Earth.
Light from the Sun takes about 8 minutes to reach Earth.
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What are comets primarily made of?
What are comets primarily made of?
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What is the distance to Proxima Centauri in light-years?
What is the distance to Proxima Centauri in light-years?
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Triangulation involves measuring distances on the ground directly.
Triangulation involves measuring distances on the ground directly.
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What causes the seasons on Earth?
What causes the seasons on Earth?
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What occurs during a total solar eclipse?
What occurs during a total solar eclipse?
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An eclipse occurs when one object in space passes in front of another, blocking sunlight. This phenomenon can be ______ or ______.
An eclipse occurs when one object in space passes in front of another, blocking sunlight. This phenomenon can be ______ or ______.
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Match the following types of eclipses with their descriptions:
Match the following types of eclipses with their descriptions:
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A total lunar eclipse occurs when only a part of the Moon is in Earth's shadow.
A total lunar eclipse occurs when only a part of the Moon is in Earth's shadow.
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What is parallax used for in astronomy?
What is parallax used for in astronomy?
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Who proposed the model of the heavens with planets revolving around the Sun?
Who proposed the model of the heavens with planets revolving around the Sun?
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The patterns of stars in the night sky are called __________.
The patterns of stars in the night sky are called __________.
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The Moon was formed from debris resulting from a collision between Earth and a planet-sized object.
The Moon was formed from debris resulting from a collision between Earth and a planet-sized object.
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The longest possible baseline for measuring distances from Earth to stars is the ______ of Earth's orbit.
The longest possible baseline for measuring distances from Earth to stars is the ______ of Earth's orbit.
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Match the following astronomers with their contributions:
Match the following astronomers with their contributions:
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Study Notes
The Big Bang Theory
- Astronomers study celestial bodies like stars, the Moon, and planets.
- The Big Bang Theory states that the universe began in an event 13.7 billion years ago.
- Before the Big Bang there was no energy, matter, or celestial bodies.
- The Big Bang gave rise to all the energy and matter in the universe.
Evidence Supporting The Big Bang Theory
- The universe started out very small, hot, and dense, and has been expanding and cooling ever since.
- Galaxies are collections of stars moving away from each other.
- Background radiation from every part of space was first detected in the 1960s.
- Space probes have mapped the background radiation.
The Expanding Universe
- Galaxies in the universe are moving away from each other as the universe expands.
Galaxies
- A galaxy is a large group of stars, gas, and dust held together by gravity.
- There might be as many as several billion galaxies in the universe, and each can contain billions of stars.
- Our Sun is part of the Milky Way galaxy.
- A nebula is a dense cloud-like collection of gas and dust in space.
- Some nebulae are places where stars are born.
Galaxy Shapes
- Spiral galaxies look like a pinwheel from above, and a plate with a ball in the center from the side.
- Elliptical galaxies have the shape of a flattened circle and range from a perfect sphere to a stretched-out sphere like a football.
- Irregular galaxies don't have a regular shape like a sphere or a pinwheel.
- Irregular galaxies have lots of gas and dust, which are the building blocks of stars.
Star Clusters vs Galaxies
- Star clusters are groups of stars that are found within galaxies.
- Globular clusters are collections of 100,000 to 1,000,000 stars held together by gravity.
- Open clusters are collections of up to a few thousand stars.
Stars
- A star is a massive, gaseous, spherical object in space that gives off light and other forms of energy due to nuclear reactions at its core.
- Nuclear reactions transform elements of one kind into elements of another.
- Hydrogen atoms fuse and become helium atoms during the life of a star.
- Nuclear fusion releases tremendous amounts of energy.
What The Color Of A Star Reveals
- The color of a star reveals its surface temperature.
- Red stars are relatively cool, about 3000°C.
- Yellow stars, such as our Sun, are fairly hot, with a surface temperature of about 6000°C.
- Whitish-blue stars are extremely hot, ranging from 20,000°C to 40,000°C.
- The color of a star also reveals clues about its composition and movement.
- The Doppler effect is the change in the wavelength of light from an object due to its motion.
How Long Stars Last
- The "life" of a star depends on its mass.
- Low mass stars (red dwarf stars) use up their hydrogen slowly and can last as long as 100 billion years.
- As they use up their hydrogen, they lose mass and end their lives as small, dim white dwarf stars.
- Intermediate mass stars like our Sun use up their hydrogen more quickly over about 10 billion years.
- When the hydrogen is used up, the core of the star contracts, the temperature rises, and the outer layers expand.
- These cooler outer layers have a red color, so stars at this stage are called red giants.
- As they continue to age, they get smaller, cooler, and dimmer becoming a white dwarf and, eventually, a black dwarf star.
- High mass stars use up their hydrogen relatively quickly, and may only last millions of years.
- When nearing the end of its life, the core of a high mass star collapses in a dramatic, powerful explosion called a supernova.
- For very high mass stars, the remaining core contracts further, resulting in a rapidly rotating, unimaginably dense neutron star.
Black Holes
- Astronomers believe that extremely massive stars can contract greatly into a super-compact, super-dense object called a black hole.
- The force of gravity in a black hole is so great that not even light can escape it.
The Sun And Its Planetary System
- The Sun is a huge sphere of mostly hydrogen gas.
- The nuclear reactions at its core generate heat, light, and other forms of energy that radiate outward.
- Over 110 Earths could fit across the Sun's diameter.
How The Planets Formed
- A solar system is a group of planets circling a star.
- A planet is a spherical object made mainly of rock or gases, which orbits a star and is large enough that its own gravity holds it in a spherical shape.
- Planets spin on an axis in a motion called rotation.
- Planets also travel around the Sun in a motion called revolution.
- Planets began to form from the gases and other matter left over after the Sun formed.
- The rocky bodies closest to the new Sun were blasted with its radiation and became the rocky, inner planets: Mercury, Venus, Earth, and Mars.
- Farther out, away from the Sun's intense heat, the outer planets kept their gases and became the gas giants: Jupiter, Saturn, Uranus, and Neptune.
- All planets except for Mercury and Venus have at least one moon.
Other Objects In The Solar System
- Throughout much of the early history of the solar system, stray rocky material and dust pounded the planets and their moons.
- Craters provide evidence of these interactions.
- Some of this rocky material remains in the form of asteroids- small objects that orbit the Sun, mainly found between Mars and Jupiter.
- Rocky material left over from the formation of the solar system is also found at its outer limits in a region called the Oort cloud.
- From this region come comets- objects made of rock and ice that orbit the Sun.
Measuring Distances In Space
- Distances between most objects in space are so great that it is hard to imagine them.
- The unit commonly used to describe distances in space is the light-year.
- Light moves faster than anything else in the universe at a speed of nearly 300,000 km/s.
- Light from the Sun takes about 8 minutes to reach Earth.
- Light from the Sun takes about 5 hours to reach Neptune, the most distant planet in our solar system.
- To reach the star that is nearest to us, called Proxima Centauri, light must travel about 4.2 years.
- A light-year represents the distance that light travels in one year.
- So the distance to Proxima Centauri is 4.2 light-years.
- Most stars in the universe are hundreds, thousands, and even millions of light-years away from us.
- The universe is huge.
Measuring Distances In Space
- People invented a technique for calculating distances on the ground indirectly: triangulation.
- Triangulation involves creating an imaginary triangle between an observer and the object.
- You need to know the length of one side of the triangle, called the baseline, and the size of the two angles created when imaginary lines are drawn from each end of the baseline to the same point on the distant object.
- For thousands of years people measured the distances to stars using triangulation and an effect called parallax.
- Parallax is the apparent change in position of a nearby object when it is viewed from two different points.
- To measure distances from Earth to stars, the longest possible baseline is the diameter of Earth's orbit.
- Sightings have to be taken six months apart.
- If a star is close enough (up to 1000 light-years), it will appear to move in relation to more distant stars.
- Then its distance can be determined using triangulation.
Earth, Moon, And Sun Interactions
- Earth's axis is tilted on an angle of 23.5°.
- This axis tilt causes light from the Sun to strike Earth at different angles during its orbit around the Sun.
- As Earth orbits the Sun, Earth's axis always points in the same direction.
- However, the amount of sunlight that falls on Earth's surface at different points in its journey is different.
- This difference is what causes the seasons.
How The Moon Formed
- Scientists think that long ago, as Earth and other inner planets were forming, a huge, planet-sized object slammed into Earth.
- The intense impact ejected large and small pieces of the young planet.
- These pieces went into orbit around Earth and, over time, built up into the object we know today as the Moon.
Eclipses
- An eclipse is the total or partial blocking of sunlight that occurs when one object in space passes in front of another.
- There are two kinds: solar eclipses and lunar eclipses.
- Both types involve the interaction of the Sun, Earth, and Moon.
- In a solar eclipse, the Moon passes between the Sun and Earth, briefly blocking our view of the Sun.
- People who observe where the full shadow of the Moon falls on Earth's surface see a total solar eclipse.
- People who observe where only part of the Moon's shadow falls see a partial solar eclipse.
- In a lunar eclipse, Earth passes between the Sun and the Moon, briefly plunging the Moon into darkness as Earth's shadow moves across it.
- When the Moon lies fully in Earth's shadow, people see a total lunar eclipse.
Constellations
- As viewed from Earth, stars seem to make unchanging patterns in the night sky.
- These patterns look like familiar objects, which people long ago grouped and named.
- These groupings of stars into familiar patterns and shapes are called constellations.
- Stars in the night sky all look as if they are close to one another and equal distances from Earth.
- In reality, all stars are separated from one another and from us by hundreds, thousands, or millions of light-years.
- Because stars and other sky objects look as if they move around Earth, Greek astronomer Ptolemy and many other people several thousand years ago thought that Earth was at the centre of the universe.
- In the early 1500s, a Polish astronomer named Copernicus proposed a model of the heavens in which planets, including a rotating Earth, revolved around the Sun.
- Italian astronomer Galileo confirmed Copernicus' model.
- In the early 1600s, a German mathematician named Kepler predicted that the planets revolved around the Sun in elliptical orbits, not circles as was thought.
- An ellipse is the shape of a flattened circle.
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Description
Explore the concept of the Big Bang Theory, evidence supporting it, and the dynamics of the expanding universe. Understand how galaxies are formed and their relationship to the universe as a whole. This quiz will test your knowledge of celestial bodies and cosmic evolution.
