Question

A. Read the passage carefully and answer the questions that follow.
A galaxy is a huge collection of gas, dust, and billions of stars all held together by
gravity) All galaxies are made up of these things but they come in many different
shapes and sizes. Spiral galaxies look like giant pinwheels. The arms of the pinwheels
are made up of stars and lots of gas and dust. Young stars
burn much hotter than
older stars, so spiral galaxies are often some of the brightest in the universe. About
20% of all galaxies are spiral galaxies. Our home galaxy, the Milky Way, is a very
good example of spiral galaxy Elliptical galaxies are shaped like stretched-out
cirdes, or ellipses. Some look almost perfectly circular whereas some others look
long and flat. These galaxies contain mostly older stars and aren't as bright as spiral
galaxies. They also have very little dust and gas. Elliptical galaxies are the largest
and most common galaxies observed. They make up about 60% of all galaxies.
Irregular galaxies don't have a single common shape. Irregular galaxies are among
the smallest galaxies scientists have observed. However, they can also be very
bright like spiral galaxies, irregular galaxies are often filled with gas, dust, and lots
of bright young stars. About 20% of all galaxies are irregular galaxies.
1. What is a galaxy?
2. How are spiral galaxies different from ellipticul galaxies?
3. What is the percentage of irregular galaxies in the Universe
4 What is common between the spiral galaxies and irregular galaxies?​

Answer 1

1) A galaxy is a huge collection of gas, dust, and billions of stars all held together by

gravity !!

2) While spiral galaxies are bright, elliptical galaxies are dim. Spiral galaxies are hotbeds of star formation, but elliptical galaxies aren't nearly as prolific because they contain less gas and dust, which means fewer new (and brighter) stars are born.

3) 20 % are irregular galaxies !!

4) The bulge and halo consist mainly of older stars, where spiral arms have more gas, dust and younger stars. ... They have a bulge and halo, like spiral galaxies, but don't have the flat disk of stars. The stars in ellipticals tend to be older. Irregular galaxies have no identifiable shape or structure to them.