Question

Choose the best answer to each of the following. Explain your reasoning with one or more complete sentences. Which of the following correctly lists our "cosmic address" from small to large? (a) Earth, solar system, Milky Way Galaxy, Local Group, Local Supercluster, universe (b) Earth, solar system, Local Group, Local Supercluster, Milky Way Galaxy, universe (c) Earth, Milky Way Galaxy, solar system, Local Group, Local Supercluster, universe.

Short answer

The correct choice is (a): Earth, solar system, Milky Way Galaxy, Local Group, Local Supercluster, universe.

Step-by-step solution

Understand the Components

Our "cosmic address" is a way to identify the location of Earth in the universe in increasing scales of size. It includes the planet we live on, the system of planets that Earth belongs to, the galaxy that our solar system is part of, and the larger structures that galaxies group into.

Break Down Each Option

Review each option individually. Option (a) lists the components as Earth, solar system, Milky Way Galaxy, Local Group, Local Supercluster, and universe. Option (b) lists them as Earth, solar system, Local Group, Local Supercluster, Milky Way Galaxy, and universe. Option (c) lists them as Earth, Milky Way Galaxy, solar system, Local Group, Local Supercluster, and universe.

Establish the Correct Order

The correct sequence from small to large should be: Earth (a planet), solar system (a group of celestial bodies with our Sun), Milky Way Galaxy (the galaxy containing our solar system), Local Group (a collection of galaxies including the Milky Way), Local Supercluster (a collection of galaxy groups including the Local Group), and universe (the totality of all space and time).

Identify the Correct Option

Compare each option with the correct order established in Step 3. Option (a) matches the correct order we established for our cosmic address from small to large. Options (b) and (c) incorrectly sequence the components.

Key concepts

Earth

Earth is our home planet and the starting point of our cosmic address journey. It is the only known planet to support life, thanks to its atmosphere, water, and suitable climate. Located within the habitable zone of the solar system, Earth is the third planet from the Sun. This location helps maintain temperatures that allow water to exist in liquid form, which is critical for life as we know it.

• Diameter: Approximately 12,742 km
• Composition: Mainly made up of iron, oxygen, silicon, magnesium, sulfur, nickel, calcium, and aluminum

Earth's rotation and revolution around the Sun play a significant role in creating the day-night cycle and seasons. Together with other planets, Earth orbits around the Sun in a path called the ecliptic.

Solar System

The solar system is a collection of celestial bodies consisting of the Sun and all objects bound by its gravity. These include eight planets, their moons, dwarf planets, and countless smaller bodies like asteroids and comets. The Sun, a G-type main-sequence star, is at the center and makes up over 99% of the system's mass.

• The Sun: The central and largest body, providing heat and light
• Planets: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune
• Moons and other celestial bodies: Orbiting many of the planets

This immense gravitational hold keeps the solar system's structure intact, with each planet following a unique elliptical orbit around the Sun.

Milky Way Galaxy

The Milky Way Galaxy is the vast, spiral galaxy that contains our solar system and several hundred billion stars. It gets its name from the milky appearance of its band of light in the sky. This galaxy is structured with a central bulge, spiral arms, and a halo.

• Magnitude: Over 100,000 light-years across
• Composition: Stars, gas, dust, dark matter

The solar system is located in one of the spiral arms named the Orion Arm. The Milky Way is part of a larger structure in the universe, known as a galaxy cluster.

Local Group

The Local Group is a collection of over 50 galaxies bound together by gravity. It is a part of a larger structure in the universe, helping to explain how galaxies are not isolated but often found in groups and clusters.

• Main Galaxies: The Milky Way, Andromeda, and Triangulum Galaxy
• Distance: Approximately 10 million light-years across
• Encompasses both large and small galaxies

The galaxies within the Local Group interact gravitationally, influencing each other's paths and sometimes even merging. This interplay is essential for understanding the dynamics and evolution of galaxies.

Local Supercluster

The Local Supercluster, also known as the Laniakea Supercluster, is the colossal galaxy supercluster that includes the Local Group. It extends across vast distances and is a significant player in the cosmos.

• Structure: Contains around 100 groups of galaxies
• Dimensions: Roughly 520 million light-years in diameter

Each galaxy group within the Local Supercluster is part of an intricate network, making up the large-scale structure of the universe. Studying this supercluster helps astronomers understand the universe's expansion and large-scale motion patterns.