Facts

The Milky Way has inspired countless artists, poets, and scientists to dig deeper and learn more about our place in the universe and inside the galaxy itself. Humans named it “milky” because of the several cloudy bands of stars.

At first glance, the Milky Way is a dim glowing band that arches across the evening sky.

From the Northern to the Southern Cross - Image Credit & Copyright: Nicholas Buer

What’s invisible to the naked eye is the fact that those "milky clouds" we observe from the Earth are actually filled with billions of planets and stars. The "milkiness" is also attributed to gases and stardust within the Milky Way’s arm spirals, where stars are born.

What's Inside the Milky Way?

Vast, expansive, enchanting, and mysterious, The Milky Way is the galaxy that earthlings like you and me call home.

All beings that inhabit Earth reside in the Milky Way, right next to our powerful star, the sun. Image Credit:NASA-GSFCA/WikiPedia

When we look at the Milky Waythrough a telescope or the naked eye, it’s easy to see that the galaxy is dense with stars, clusters and stardust, but the number of stars is nearly impossible to count. Part of the reason for this is that the Milky Way is also gigantic – measuring 100,000 to 120,000 light years in diameter and containing between 100 and 400 billion stars. Scientists think there could also be up to 100 billion planets in the Milky Way, which makes our little home called Earth seem very small, indeed, in the big scheme of things.

The most stars you can see from your backyard (or any other spot on earth at a given time) when you look up into the night sky are about 2,500. This number can easily change, because the Milky Way is ever evolving and expanding. Even though the galaxy often loses stars through supernova – about seven every year -- new stars are constantly being born.

Inside the Milky Way, the cycle of star life and death take their course in a brilliant, dramatic manner. Watch the life cycle of a star below:

Stellar-mass Black Holes

Stellar-mass black holes form from the most massive stars when their lives end in supernova explosions. As both the birthplace and scene of star death, the Milky Way galaxy contains some 100 billion stars. Roughly one out of every thousand stars that forms is massive enough to become a black hole. Scientists believe that our galaxy must harbor a massive amount of stellar-mass black hole, somewhere in the vicinity of 100 million.

(Image Credit: ESA / V. Beckmann (NASA-GSFC)/SpaceTelescope.org

It sparks the imagination to think of what else is hidden from view in our galaxy. What other planets are like ours? Is there life? What’s on the other side of a black hole? How many stars are there? Scientists are constantly researching, using telescopes and equipment to capture data, and observing the Milky Way galaxy to explore the answers to these questions and more.

Collision Course

The Milky Way as we know it will eventually cease to exist. The Andromeda Galaxy is approaching the Milky Way at about 110 kilometres per second (68 mi/s) and in 2012, scientists studying the movements of Andromeda using the Hubble Space Telescope discovered that a collision with the Andromeda galaxy is inevitable in about 3.75 billion years.

There is little chance, however, that any individual stars or planets will collide, and although it will shift the position of our galaxy, it’s also predicted that Earth will have become far too hot to sustain live by the time this takes place.

(The Andromeda Galaxy and the Milk Way Galaxy will eventually merge into one. Image Credit: NASA; ESA; Z. Levay and R. van der Marel, STScI; T. Hallas; and A. Mellinger; businessinsider.com)

Milky way Age

The Milky Way isn’t as young as it first appeared to astronomers. Although our own life sustaining star, the sun, is relatively young, recent discoveries have suggested that the galaxy itself is as old as the universe itself. The galaxy is over 13 billion years of age, which provides a partial explanation for all the stardust and gases floating about – it’s expected that after so many years, some of the stars, planets, and other matter would have disintegrated.

What’s currently unknown (but theories abound) about the Milky Way’s gases and stardust is that the galaxy seems to have a replenishing supply of hydrogen available, even after a star dies out.

The Milky Way is a barred spiral galaxy, about 100,000 light-years across. If you could look down on it from the top, you would see a bulge of gas and stardust surrounded by four large spiral arms that wrap around it. Spiral galaxies make up about two-third of the galaxies in the universe.

About one brand new star is born inside the Milky Way every year.

(Cepheus B, a molecular cloud located in our Milky Way, about 2,400 light years away, provides scientists with an excellent model to determine how stars are formed. Image Credit: Getman et al.; IRL NASA/JPL-Caltech/CfA/J. Wang et al, phys.org)

Spiral Arms

It’s important to remember that the universe is enormous, so incredibly huge, that mapping it will take decades. Curled around the center of the galaxy, the spiral arms contain a high amount of dust and gas. The expansive galaxy takes up a space that’s several hundred billion times the mass of the Sun. (That’s 100,000,000,000 times 2 or 3 for all the number crunchers out there.)

The vast and expansive barred spiral galaxy is about 100,000 light-years across.

If you could look down on our galaxy from the top, you would see a central mass of clusters, gas, stars, planets and stardust surrounded by four large spiral arms that wrap around it.

Spiral galaxies are one of the most common galaxies in the universe, making up about two thirds of the galaxies science has discovered so far.

(Image Credit: ESA / V. Beckmann (NASA-GSFC)

Scientists have recently discovered that the Milky Way’s spiral structure has a small central bar structure in the center of it. (Illustration Credit: R. Hurt (SSC), JPL-Caltech, NASA) space.com

The Milky Way’s barred spiral contains a bar across its center region, and has two major arms. Scientists believe that the four arms are made up of the youngest, newest stars and older stars have migrated outward to fill the gaps between the arms.

Inside The Orion Arm is Our Solar System.

Earth’s life-sustaining star, our sun, lies about two-thirds of the way out from the center on an outcropping called the Orion Spur. The Orion arm is located between two major arms, Perseus and Sagittarius.

New information obtained by the Very Long Baseline Array radio observatory indicates that our Local Arm is not just a spur. It’s possible it’s either a large branch off the Perseus arm or a major arm unto itself.

All beings that inhabit Earth reside in the Milky Way, right next to our powerful star, the sun. Image Credit:NASA-GSFCA/WikiPedia

Our Big Brother

One of the galaxies most similar to our Milky Way is NGC 6744. It’s bigger than the Milky Way, with a disk stretching 175,000 light-years across. It, too, has fluffy spiral arms. NGC 6744 has helped scientists understand how and star formation can occur in the outer regions of galaxies. Close by to NGC 6744 is a small, distorted companion galaxy that scientists have compared to the Milky Way’s Large Magellanic Cloud.

(The Galaxy Evolution Explorer (GALEX) brought images like thgese back after a decade of operations in which it used ultraviolet vision to study hundreds of millions of galaxies across 10 billion years of cosmic time. Image Credit: NASA/JPL-Caltech; focus.it)