When we think of where we are in the entire universe, our planet is just one a small speck. Even our solar system is one of many in the Milky Way Galaxy, and our own galaxy is one of billions in the universe. It’s hard to image how big the universe actually is. But with advanced technology, we have a better understanding of what lies in the deepest parts of space. Just in our own Milky Way Galaxy, we have numerous suns, planets, solar systems, comets, black holes, and so much more. Here are 10 interesting facts about our Milky Way Galaxy…
10. Structure And Size Of The Milky Way Galaxy
The Milky Way is a barred spiral galaxy with a center bulge that is surrounded by four arms that are wrapped around it. Around two-thirds of all the galaxies in our universe are shaped in a spiral. Our galaxy, as well as our solar system, is always rotating. While our solar system travels around 515,000 miles-per-hour on average, it would still take approximately 230 million years to travel around the Milky Way.
Our galaxy is around 100,000 light-years across and has a mass of between 400 and 780 billion times the mass of our own sun. 90% of its mass is believed to be dark matter.
There is a huge halo of hot gas surrounding our galaxy that stretches for hundreds of thousands of light-years. While it is believed to be as huge as all of the stars put together in the Milky Way, the halo itself only has around 2% of the amount of stars that are found inside of the disk.
And at the heart of the Milky Way galaxy is the galactic bulge which contains gas, stars, and dust that’s so thick you can’t even see into it, let alone to the other side.
9. The Andromeda Galaxy Will Eventually Collide With The Milky Way
The Milky Way and Andromeda galaxies will eventually collide into each other, but it won’t happen for a very long time. While it was previously thought that it would happen 3.75 billion years from now, newly conducted research from the ESA’s Gaia mission estimates the collision will take place in 4.5 billion years.
And we may not get hit as hard as previously thought. The new research also suggests that it won’t be a full force collision and rather a “tidal interaction,” which means that no planets or stars will collide with each other.
There is a group of more than 54 galaxies that are named the Local Group, of which Andromeda and the Milky Way are a part. These two galaxies, as well as the Triangulum Galaxy, are the three largest in the group. Andromeda is the most massive galaxy, while the Milky Way ranks second, and the Triangulum is third. Andromeda and Triangulum are both spiral galaxies and are situated between 2.5 and 3 million light years away from the Milky Way.
8. Our Galaxy Is Warped And Twisted Instead Of Being Flat
It’s always been said that our galaxy is flat as a pancake, but a recent study revealed that the Milky Way is in fact warped and twisted. The farther away the stars are from the center of the galaxy, the more they become warped and twisted in an S-like appearance.
Over 1,000 Cepheid variable stars (1,339 to be exact) were used in a study conducted by astronomers from Macquarie University as well as the Chinese Academy of Sciences. These stars became bright and dim in a manner that changed according to their luminosity. The data collected from these stars by using the Wide-field Infrared Survey Explorer (or WISE) let astronomers create a 3D map of the true shape of our galaxy.
While the Milky Way is now confirmed to be warped and twisted, it’s not the only one out there that’s like that. While it’s not overly common, astronomers have confirmed that a dozen other galaxies in the universe have twisted spiral patterns in their outer-most areas.
7. There Are Hundreds Of Billions Of Stars In Our Galaxy
It’s tough to know exactly how many stars there are in our galaxy since the halo around the Milky Way also contains many stars. In addition, the center of our galaxy has a galactic bulge that’s filled with dust, stars, and gas, as well as a supermassive black hole which makes that area extremely thick with materials that telescopes are unable to see through it.
While around 90% of our galaxy’s mass is made up of dark matter, the majority of the remaining 10% is dust and gas, it is believe that only about 3% of the Milky Way’s mass is made up of stars. Some researchers believe that there are approximately 100 billion stars in our galaxy, while others say that there are much more - between 400 and 700 billion.
The European Space Agency’s Gaia mission is mapping out the locations of around 1 billion stars in the Milky Way, so that’s a good start.
6. There’s A Supermassive Black Hole At The Heart Of Our Galaxy
It is believed that most, if not all, galaxies have a supermassive black hole at their center and the Milky Way has one that weighs as much as 4 million suns. Sagittarius A*, which is the massive object located at the center of our galaxy, has been observed for the past several years. Although black holes can’t actually be seen, scientists study them by observing the materials that are orbiting around them.
Scientists wanted to measure the effects of gravity near the black hole so they decided to observe a small star called S2 that orbits deep within Sagittarius A*’s gravity well every 16 years. They noticed three bright flares that traveled around the black hole’s event horizon at approximately 216 million miles per hour (or 30% of the speed of light).
Scientists previously believed that there were only small and supermassive black holes, but there are in fact medium-sized (or intermediate) black holes that are rare but they do exist, and we’ll talk about that in the next entry…
5. There’s Also A Jupiter-Sized Black Hole Wandering Around Our Galaxy
New research indicates that a rare Jupiter-sized black hole is wandering around our galaxy. The data came from the Atacama Large Millimeter/submillimeter Array (or ALMA) which includes 66 telescopes that are placed across the Atacama Desert located in the northern part of Chile.
The data consisted of the scientists observing two gas clouds, called Balloon and Stream in reference to their shapes, and what they witnessed during their two-day observation period in May 2018 was that the gas clouds were moving in an odd pattern, like they were spinning around an invisible center in a location where no light was coming from.
The team determined that the object was an uncommon medium-sized black hole that has around 30,000 times the mass of our sun and is approximately the size of Jupiter.
4. Earth Is At The Center Of The Habitable Zone In Our Galaxy
For the last two decades, astronomers have modeled the evolution of our galaxy in order to figure out the four essentials needed for complex life - the existence of a host star; a sufficient amount of heavy elements to create terrestrial planets (like Earth); enough time for biological evolution; and an environment without gamma ray bursts or life-threatening supernovae.
Almost 4,000 exoplanets and nearly 3,000 planetary systems have been confirmed to exist in our galaxy. Hundreds of those star systems have more than one planet that is within the Galactic Habitable Zone (or GHZ) and there is no doubt that many more are out there just waiting to be discovered.
And of course Earth is located at a perfect spot near the center of our galaxy’s GHZ. What’s even more interesting is that according to astrophysicists at the Australian National University, the GHZ only has about 10% of all the stars in the Milky Way.
3. There Are Almost 4,000 Exoplanets In Our Galaxy
Planets that are beyond our solar system are called exoplanets and thousands have been discovered by NASA’s Kepler Space Telescope over the past several years. These exoplanets can be any size, with some being rocky and others having icy surfaces.
The Kepler Space Telescope worked to find these planets from 2009 until 2018. During that time, it discovered 2,682 exoplanets with over 2,900 possible candidates that are still waiting to be confirmed. And according to information found on NASA’s website, a total of 3,916 exoplanets (including the ones found by Kepler) have been confirmed.
Kepler ran out of gas and was officially decommissioned in November 2018. However, a new spacecraft, called the Transiting Exoplanet Survey Satellite (or TESS) has taken its place to find new planets. It was launched in April of 2018 and is planning to scan around 85% of the sky in its two-year mission.
2. So Far, Almost 3,000 Planetary Systems Have Been Discovered In Our Galaxy
Another important piece of information presented on NASA’s website is that 2,917 planetary systems have already been discovered. One of those planetary systems which is very similar is our own solar system is called Kepler-90 which is located approximately 2,500 light years away from us towards the Draco Constellation.
Kepler-90 has eight planets which is the same number of planets located in our solar system. Other similarities between the two solar systems are that Kepler-90 has a G-type star which is comparable to our own sun; it has rocky planets like ours; and it has other large planets that are similar in size to Saturn and Jupiter.
One major difference between the two solar systems is that Kepler-90’s planets all orbit very close to their sun which would indicate that they may be too hot to sustain any type of life. But with further research, more planets could potentially be discovered that orbit at a further distance.
1. Milky Way Is Only One Of Hundreds Of Billions Of Galaxies In The Universe
According to data collected from NASA’s Hubble Space Telescope, it was previously thought that there were around 200 billion galaxies in the universe. However, it is now believed that there are at least ten times more galaxies out there in space.
Some experts believe that around 90% of the galaxies in the observable universe are too far away and even too faint to see with our telescopes. Thankfully, the James Webb Space Telescope (or JWST) is scheduled to be launched in early 2021 which will help to see these faint galaxies and perhaps uncover even more.
Some of the tasks the JWST will conduct will be to find out what happened after the first stars were formed following the Big Bang; finding out how galaxies were formed and assembled; the birth of stars and protoplanetary systems; and understanding the atmospheres on distant planets to find out if they are habitable and can sustain life.
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