EASC Lesson 4 - Galaxies

The student is expected to categorize galaxies as spiral, elliptical, and irregular and locate Earth's solar system within the Milky Way galaxy

What is a galaxy?

A galaxy is a collection of stars, dust, gas, and dark matter, bound together by gravitational attraction due to their own mass.

What are the main types of galaxies?

The three main types of galaxies are: 1. Spiral 2. Elliptical 3. Irregular

How did Edwin Hubble classify galaxies?

Edwin Hubble created a classification system for galaxies based on their shapes, often referred to as the Hubble tuning-fork.

What can you find in elliptical galaxies?

Elliptical galaxies generally contain very little gas and dust, and are mostly composed of old, red stars.

How do spiral galaxies differ from elliptical galaxies?

Spiral galaxies are characterized by their flat disk structure with spiral arms containing stars, gas, and dust, while elliptical galaxies have an ellipse shape and less star formation.

What are barred spiral galaxies?

Barred spiral galaxies are a type of spiral galaxy with a central bar-shaped structure made of stars.

What are irregular galaxies?

Irregular galaxies do not have a defined shape or structure, often appearing chaotic without a bulge or spiral arms.

What is the size of our Milky Way galaxy in terms of diameter?

The Milky Way galaxy is estimated to have a diameter of about 100,000 light-years.

What does the Orion Arm refer to?

The Orion Arm is the specific spiral arm of the Milky Way galaxy where our Solar System is located.

How many galaxies are estimated to exist in the universe?

Astronomers believe there could be as many as 100 billion galaxies in the universe.

What is the Virgo Supercluster?

The Virgo Supercluster is a large group of galaxy clusters, including the Local Group, within which the Milky Way is located.

What is the significance of Hubble's Ultra Deep Field?

Hubble's Ultra Deep Field provided a view of nearly 10,000 galaxies, illustrating the vast number of galaxies in a small patch of the universe.

How are stars in elliptical galaxies characterized?

Stars in elliptical galaxies are generally older, red stars, and these galaxies tend to look yellow-red in color.

What phenomenon is associated with new star formation in spiral galaxies?

The spiral arms of spiral galaxies are often sites where new stars are born, leading to brightness due to the young, hot, blue stars.

What does the term 'Laniakea Supercluster' refer to?

The Laniakea Supercluster is a vast collection of galaxy clusters, encompassing about 300–500 smaller clusters and 100,000 galaxies.

What are the Large and Small Magellanic Clouds?

The Large and Small Magellanic Clouds are irregular dwarf galaxies close to the Milky Way, located about 160,000 light-years away.