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New 3-D picture of the Milky Way Galaxy

This article first appeared in the 9/6/19 edition of the Davis Enterprise.

New 3-D picture of the Milky Way Galaxy

Milky Way laying above a lady's silhouette, at Trona Pinnacles National Landmark, California. Photo by Ian Norman, obtained from Wikimedia Commons.


New 3-D picture of the Milky Way Galaxy

by Vinita Domier

Davis Astronomy Club


On August 1, 2019, a team of astronomers announced that the Milky Way Galaxy is not a flat spiral disk as previously assumed but instead is a warped and twisted spiral resembling a flattened sideways ‘S’ with a central bulge. This new three-dimensional picture of the galaxy was obtained by directly measuring with great accuracy the distances of 2400 special type of super luminous Cepheid variable stars from the sun using the Warsaw Telescope located in the Chilean Atacama Desert.


A galaxy is a group of stars that are gravitationally bound to each other and move through space as one unit. All the stars that we can see with our naked eyes and resolve individually with backyard telescopes belong to the Milky Way Galaxy which, along with billions of planets, asteroids, comets, interstellar gas and dust, and dark matter, is estimated to contain 200 - 400 billion individual stars. 


Until a century ago, it was assumed that the Milky Way Galaxy was the entire universe. Using state-of-the-art telescope at Mount Wilson in California, Edwin Hubble conclusively proved in 1924 that numerous fuzzy celestial nebulae were galaxies. He categorized them as elliptical, spiral, lenticular, and irregular depending on their shapes. There are estimated to be 100 – 200 billion galaxies in the observable universe.


As we observe the Milky Way Galaxy from within it, astronomers have used indirect methods to determine its shape and size – a mostly flat barred spiral galaxy that is a 200,000 light years diameter disk with a 10,000 light years bulge in the middle. Our sun is located about 25,000 light years from the galactic center where a supermassive black hole known as Sagittarius A* is located. 


Even though the entire Milky Way Galaxy is not visible from our vantage point, the edge of the galaxy’s disk can be observed. It appears to the naked eye as a faint white band about 30 degrees wide arching across the night sky resembling a celestial river of milk. Milky Way is the literal English translation of its Latin name ‘via lactea’ which is derived from the Greek word ‘galaxias’ meaning milky circle. Galileo Galilei was the first person to point his telescope at the Milky Way in 1610 and discover that the collective light was emanating from billions of stars. 


One of the most awesome sights to behold in a dark moonless and cloudless night is the hazy ribbon of the Milky Way spanning the sky from horizon to horizon. Unfortunately, even though no equipment is needed for viewing but one’s eyes, most never experience its stark beauty unless they travel to rural areas away from city lights.


Everyone is invited to the Saturday, September 7meeting of the Davis Astronomy Club atExplorit Science Center (3141 5thStreet, Davis) starting at 7:30pm. This is a free meeting, and all ages are welcome to attend the featured presentation indoors where we will discuss the Milky Way Galaxy, followed by the star party outdoors where we will view the waxing gibbous moon and the gas giant planets Jupiter and Saturn.





Explorit's coming events:


·     “Rummage Sale for Science” on Saturday, September 7thfrom 8am-2pm.  Furniture, storage racks, posters, plexi-glass, t-shirts, tools, rocks and minerals, and more!  All proceeds will help support the upcoming exhibit change.


·     Grand Opening, Sunday, September 29.  Member and Donor viewing from 12-1pm, general public welcome from 1-5pm.  “Make Waves” with our new hands on exhibit of Light & Sound in the Anne Hance Exploration Gallery.  Sponsorship opportunities available at




·     Nature Bowl now enrolling for the school year.  Call (530) 756-0191 to register.  $25 fee covers weekly meeting space and a t-shirt.  Informational meeting on Monday, September 9 from 6-7pm at Explorit.

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