Astronomy Chapter 1 Flashcards

Questions and Answers

What do astronomers mean by the Big Bang?

The event that marked the beginning of the expansion of the universe.

How many galaxies are there in the observable universe?

Roughly (within a factor of 10) the same as the number of stars in our galaxy.

The Sun is mainly made of?

Hydrogen and helium.

What does 1.1 The Scale of the Universe refer to?

Our solar system belongs to the huge, disk-shaped collection of stars called the Milky Way Galaxy. Signup and view all the answers

How big is the universe?

If we imagine our Sun as a large grapefruit, Earth is a ballpoint that orbits 15 meters away; the nearest stars are thousands of kilometers away on the same scale. Signup and view all the answers

Which of the following has your 'address' in the correct order?

You, Earth, solar system, Milky Way, Local Supercluster, Local Group Signup and view all the answers

About where is our solar system located within the Milky Way Galaxy?

About halfway from the center of the galaxy to the outskirts of the galactic disk. Signup and view all the answers

What do we mean when we say that the universe is expanding?

All galaxies are increasingly moving away from one another. Signup and view all the answers

One light-hour is the distance that light travels in an hour. How far is this, in kilometers?

1.08 billion km Signup and view all the answers

Suppose we imagine the Sun to be about the size of a grapefruit. What describes the size and distance of Earth on the same scale?

Earth is the size of a tip of a ballpoint pen about 15 meters away from the Sun. Signup and view all the answers

On the 1-to-10-billion scale, about how far is it to the nearest stars besides the Sun?

4,400 kilometers. Signup and view all the answers

What is nuclear fusion?

The process in which lightweight atomic nuclei smash together and stick (or fuse) to make heavier nuclei. Signup and view all the answers

Earth is made mostly of metals and rocks. Where did this material come from?

It was produced by the nuclear fusion in stars that made the heavy elements. Signup and view all the answers

All galaxies beyond those local to the Milky Way appear to be receding from us.

True Signup and view all the answers

On a cosmic calendar, in which the history of the universe is compressed into 1 year, when did the dinosaurs become extinct?

In late December. Signup and view all the answers

The fact that nearly all galaxies are moving away from us, with more distant ones moving faster, helped us to conclude that:

The universe is expanding. Signup and view all the answers

The age of our solar system is about:

One-third of the age of the universe. Signup and view all the answers

An astronomical unit is:

Earth's average distance from the Sun. Signup and view all the answers

Most of the mass in the Milky Way Galaxy is located:

In the halo (above/below the disk). Signup and view all the answers

How long does it take our solar system to complete one orbit around the Milky Way Galaxy?

230 million years. Signup and view all the answers

Patterns of stars in constellations hardly change in appearance over times of even a few thousand years. Why?

Signup and view all the answers

Study Notes

Cosmology and the Universe

The Big Bang marks the beginning of the universe's expansion.
The observable universe contains roughly the same number of galaxies as the stars in the Milky Way.
The universe is continuously expanding, with galaxies moving away from each other.

Structure of the Universe

Our solar system resides in the Milky Way Galaxy, a massive disk-shaped collection of stars.
The solar system is located about halfway from the Milky Way's center to its outskirts.
The "address" of an individual includes: you, Earth, solar system, Milky Way, Local Group, and Local Supercluster.

Size and Scale

On a scale where the Sun is a grapefruit, Earth is a ballpoint tip located 15 meters away; the nearest stars are thousands of kilometers distant.
One light-hour equals approximately 1.08 billion kilometers.
On a 1-to-10-billion scale, the nearest stars are roughly 4,400 kilometers away.

Solar System and Galaxy Composition

The Sun is primarily composed of hydrogen and helium.
Earth is made mostly of metals and rocks, originating from heavy elements produced by nuclear fusion in stars.

Galactic Properties

Most mass in the Milky Way is found in the halo, above and below the galactic disk.
The solar system takes about 230 million years to complete one orbit around the Milky Way.

Light and Energy Processes

Nuclear fusion involves lightweight atomic nuclei fusing to form heavier nuclei, a process that powers stars.

Cosmic Timeline

On a cosmic calendar, dinosaurs became extinct in late December, illustrating the vast timescale of the universe.
The age of the solar system is approximately one-third that of the universe.

Stellar Patterns

Constellation patterns remain nearly unchanged over thousands of years due to the vast distances between stars.

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Description

Test your knowledge of the universe with these flashcards from Chapter 1. Explore key concepts such as the Big Bang, the number of galaxies, and the composition of the Sun. Ideal for students looking to reinforce their understanding of astronomy.