<center><h3> The Milky Way galaxy is our home, we should probably look around</h3></center>

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Our home galaxy is the Milky Way. It contains over 200 billions stars and is over 100,000 light years across. That is massive, so measuring even the nearby parts is extremely time consuming. [1]
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<div class="pull-right"><center><img src="https://upload.wikimedia.org/wikipedia/commons/thumb/4/43/ESO-VLT-Laser-phot-33a-07.jpg/1200px-ESO-VLT-Laser-phot-33a-07.jpg" border="0"><br/><em><a href="https://upload.wikimedia.org/wikipedia/commons/thumb/4/43/ESO-VLT-Laser-phot-33a-07.jpg/1200px-ESO-VLT-Laser-phot-33a-07.jpg">source</a></em></center></div>
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<center><h3> Complications </h3></center>
Mapping the Milky Way is difficult for a variety of reasons. As previously mentioned, the Milky Way is massive. If you figured out the position of one star a second, it would take you 70,400 years just to map every one. Nobody has that much time. 

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Another major problem is of our location. We are inside of the milky way galaxy, which means a lot of objects will block our view. The outer edges and spirals of the Milky Way have massive amounts of dust, which is hard to see through. It is also very hard for us to see anything of the other side of the galaxy. Any light rays that do somehow make it to us are drowned out and distorted by the rest of the galaxy. This means we can not see all, or even the majority, of the galaxy. [2]

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<center><h3> Collecting Data </h3></center>
We are scanning the sky in many different ways with many different projects. This produces a massive amount of data which can all be combined to fill in different areas. 


<center>*WISE*</center>
WISE, or Wide-field Infrared Survey Explorer, is one such source of data. WISE took infrared pictures of the entire sky, multiple times. This is a massive amount of data and has found an estimated 750 million objects. It finished scanning the sky in 2011, but scientists are still going through the data. [3]

This data is often used for many different things. Finding NEO is one important example. Another is looking beyond our solar system. WISE data has helped us understand the shape of the spiral arm we are located in. Dust often glows in infrared and the spiral arm is made up mostly of dust clouds. [4]


<center>*Gaia*</center>
The Gaia satellite has been sitting about 1.5 million miles out from Earth's orbit taking pictures of the Milky way since 2013. This telescope has found over a billion different stars. This is the biggest mapping project that has happened.   [5]


<center>*Spitzer infrared space telescope*</center>
The Spitzer infrared space telescope was used to figure out the general shape of our galaxy. After that it has also taken a 360 degree view of the Milky Way. This is being used to figure out where the edges of the galaxy are located.[6]

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Through this we have learned enough to figure out the general shape of our galaxy and our position in it.


<div><center><img src="https://www.nasa.gov/sites/default/files/thumbnails/image/pia19341-nasa_denilso_camargo_rev_v05.jpg
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Astronomers disagree on the names and roles of some of these arms. Robert Hurt viewed the Milky Way as two major arms and two minor ones, although some astronomers think all 4 are major. This is due to arguments over what actually defines a major arm. They have enough matter, but seem to not produce enough stars. [7]

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In the end the exact designation of the arms is not as important as how much we know about them. The Milky way is massive, and we have only mapped the general shape of the Milky way and the areas close by. Throughout the future we will hopefully learn more.

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[[1]](https://www.space.com/19915-milky-way-galaxy.html) [[2]](https://www.nasa.gov/jpl/charting-the-milky-way-from-the-inside-out) [[3]](https://www.nasa.gov/mission_pages/WISE/mission/index.html) [[4]](https://www.nasa.gov/jpl/charting-the-milky-way-from-the-inside-out) [[5]](https://phys.org/news/2016-09-galaxy-milky-revealed.html) [[6]](https://www.jpl.nasa.gov/news/news.php?feature=4085) [[7]](http://galaxymap.org/drupal/node/171)