Explain: Milky Way Galaxy

The Milky Way is a barred spiral galaxy, one of hundreds of billions in the observable universe. It is also our home.

Like other galaxies, the Milky Way is an isolated collection of stars and other materials held together by their common gravity. In addition of the 100 to 400 billion stars in our galaxy, there are probably a similar number of planets in the Milky Way, some of them part of solar systems and some of them floating freely. There are countless nebulae under the stars, which are clouds of gas and dust.

The vast majority of interstellar gas is made up of hydrogen and helium, but several lines of evidence, most notably that material in the galaxy orbiting the center too quickly for the gravity of visible objects to hold together, suggest that most of the mass is by The Milky Way is made up of a type of matter that does not interact with light. Astronomers call this dark matter, and its true nature is not fully understood.

Who discovered the Milky Way?

From our perspective on earth, the Milky Way looks like a diffuse band of light that stretches across the night sky. Hence the English name: The Romans called it the Milky Way and imagined it to be a band of spilled milk. Astronomers and philosophers debated the nature of the Milky Way until Galileo Galilei first observed it with a telescope and discovered that the light in the Milky Way comes from countless distant stars. The stars themselves are too far away to see them all individually, but their combined light makes the familiar band.

Until the early 20th century, astronomers assumed that the Milky Way contained all the stars in the universe (or the Milky Way expanded to fill the entire cosmos, or was finite in size and surrounded by an infinite void). Astronomer Edwin Hubble made detailed observations of the Andromeda Nebula and revealed that it was its own “island” of stars – a galaxy of its own – which, according to Britannica, is millions of light years away from us.

What does the Milky Way look like?

The Milky Way is a relatively thin and flattened structure. . This explains why it appears as a band in our heaven. If we look towards the disk, the Earthlings see the combined light of all the stars in the galaxy. If we look away from the disk in one direction, we only see the stars near our solar system.

The Milky Way is made up of three main parts: the core, the disk, and the halo.

The core is not spherical; it extends in the form of a bar between 5,000 and 20,000 light years long. Up to a quarter of all stars in the Milky Way are in the core; According to the Space Telescope Science Institute, the density of stars there is up to a million times greater than near the sun. At the center of the galaxy is Sagittarius A *, a supermassive black hole with a mass 4.1 million times larger than the Sun, according to the UCLA Galactic Center Group.

The stellar disk of the Milky Way has a radius of 75,000 to 100,000 light years, but is only about 1,000 light years thick. Inside the disk are several important spiral arms, according to NASA, where the density of stars and gas is above average and star formation occurs at a higher rate, which highlights these arms when observing.

Our solar system sits in disk about 27,000 light years from the galactic center, near the inner edge of the Orion arm.

Behind the disk of the Milky Way is its halo, a spherical region with a radius of about 100,000 light years. The halo contains ancient stars and globular clusters, all of which orbit the galactic center in random directions.Dark matter extends even further, up to 400,000 light years from the center, according to a study published in the journal Astronomy and Astrophysics in 2019.

Where is the Milky Way?

The Milky Way has two large satellite galaxies: the Large and Small Magellanic Clouds. – and dozens of smaller satellites. Our closest neighbor is the Andromeda Galaxy, about 2.5 million light years away. Together with Andromeda and about 80 smaller galaxies, the Milky Way belongs to the Local Group, a group of galaxies. about 10 million light years in diameter held together by their shared gravity, according to Swinburne University.

The Local Group is a member of a larger structure called the Virgo Supercluster, which is surrounded by several large intergalactic cavities, according to Durham University. This supercluster is located in the Virgo Cluster, a huge collection of 1,000 to 2,000 galaxies about 54 million light years away. ent an even larger structure called the Laniakea Supercluster.

How big is the Milky Way?

It is difficult to estimate the true size of our galaxy because we live in it and all the gas and dust clouds obscure our observations. Astronomers estimate that the total mass of the Milky Way galaxy is roughly a trillion times the mass of the sun. According to NASA, most of this mass is by far in the form of dark matter; Stars make up only about 1% of the galaxy’s mass and interstellar gas only makes up 0.1%.

Is the Milky Way moving?

In relation to the total extent of space that separates galaxies from one another (on average), the Milky Way moves at around 391 miles per second (630 kilometers per second), scientists reported in 2005 on the preprint server arXiv. Our galaxy is on a collision course with Andromeda, and our two galaxies will crash and begin to merge in about 5 billion years.

Both the Milky Way and Andromeda are moving together towards what is known as the Great Attractor, the University of Hawaii Institute of Astronomy reported. The Great Attractor is believed to be the center of the Laniakea supercluster. The local universe is difficult because it is out of the direction of our galactic center and blocks our view.

ADDITIONAL RESOURCES

• California Academy of Sciences has this great educational video that lets students tour the Milky Way.
• This National Geographic Book “Visual Galaxy” has gorgeous images of the Milky Way.
• Check out these activities and resources about the solar system and night sky at the McDonald Observatory.