Messier Charles The first galaxies were discovered in the 17th century by the French astronomer Charles Messier, who had no idea what they were at the time. Messier, a proficient comet viewer, noticed a number of other fuzzy objects in the sky that he knew were not comets. He wrote about them in his catalogue M57 97 which now bears his name. These objects weren't known at the time but today we call them galaxies.
Galaxies are large aggregates of stars and other matter that orbit around galactic centers. They are found in clusters or alone. Our Milky Way Galaxy is one of billions in the Universe. It has hundreds of millions of stars and contains plenty of matter for life beyond Earth's.
Stars are formed from clouds of gas and dust. Young stars like our Sun will eventually explode as supernovae leaving behind heavy elements such as gold, silver, platinum and zinc. These elements are returned back into space when a star dies. Older stars like the Sun will slowly burn out and die. But even after all the fuel is used up, their cores will remain and these are called dead stars. Galaxies contain many billions of stars so there will always be new discoveries to be made.
In 1916 American astronomer Edwin Hubble proved that everything in the Universe is moving away from each other. This includes stars, planets, galaxies and even us!
On August 28, 1758, Messier found a tiny nebulous (fuzzy) object in the constellation Taurus while hunting. The Crab Nebula, now known as M1, was the first to be included in what would later become the most renowned list of galaxies, nebulae, and star clusters ever produced. It took its name from the fact that it resembled the back of the hand of the French astronomer Charles Messier.
Messier is also credited with discovering several other objects now included in the List of Star Clusters and Nebulae by Charles Messier. These include M42, now known as the Orion Nebula, and M31, the Great Andromeda Galaxy. He also noted down details about these objects which allowed others to identify them with certainty when he could not be present.
He published his notes in a book called Catalogue des Nébuleuses et des Étoiles Filantes (Cannonball of 18 Stars). This list has been very useful for astronomers because it enabled them to compare their observations with those made by others. However, it had one major drawback: it was only valid up to 1765 because after that date more recent discoveries had to be ignored. So, today's astronomers consider the List of Star Clusters and Nebulae by Charles Messier to be complete up to M110, discovered by William Herschel in 1786.
Edwin Hubble was the first person to categorize galaxies after discovering what they were. Even today, astronomers utilize his method, known as the "Hubble Tuning Fork." First, Hubble classified galaxies into two types: elliptical and spiral galaxies. He then went on to divide these categories into subgroups based on various characteristics of each galaxy.
Elliptical galaxies are spheroidal in shape with no visible structure beyond the central bulge. They are usually very smooth and have little or no dust content. The brightest stars in an elliptical galaxy are just bright enough to see with the unaided eye from Earth. Most ellipticals are thought to be formed when single large star collapses under its own weight forming a black hole that gets smaller over time due to matter falling into it.
Spiral galaxies are shaped like a spiral pattern with stars spreading out from a central point in the galaxy. These galaxies often contain many stellar nurseries called galactic nuclei where new stars are born from clouds of gas and dust. Spiral galaxies are divided into two main groups: disk galaxies and irregular galaxies. Disk galaxies such as our Milky Way Galaxy has a flat plane called the disk while the rest of the galaxy is made up of dark matter which does not emit any light itself but influences how other matter moves within the galaxy.