It took over a decade and 1,000 hours of photography to create this picture of the Milky Way

<ul class="summary-list"><li>The photographer J-P Metsavainio captured images of the Milky Way for 12 years to create a mosaic.</li><li>It shows 20 million stars in the galaxy and features the remains of three supernovas.</li></ul><p>The <keyword id="410481" type="ORGANIZATION" weightage="60" keywordseo="Milky-Way-Galaxy">Milky Way galaxy</keyword> is <a href="https://www.sciencenews.org/article/astronomers-have-found-edge-milky-way-size">nearly 2 million light-years</a> across. To visualize even a small chunk of this collection of asteroids, stars, planets, dust, and gas, photographers have to piece together a vast collection of telescope images.</p><p>For the past 12 years, the photographer J-P Metsavainio has undertaken that challenge.</p><p>Metsavainio started taking snapshots of the Milky Way from his observatory in Oulu, Finland, in 2009. Earlier this month, he <a href="https://astroanarchy.blogspot.com/2021/03/gigapixel-mosaic-of-milky-way-1250.html">released a mosaic image of the galaxy</a> that stretches from Taurus, a <keyword id="114188" type="COMPANY" weightage="60" keywordseo="Constellation">constellation</keyword> about 2,200 light-years from Earth, to Cygnus, another constellation about 6,100 light-years away.</p><p>The mosaic captures about 20 million stars in total. (The entire Milky Way has hundreds of billions of stars.)</p><p>It also features objects that are tough to catch on camera, like the remains of three supernovas.</p><p>"When you work with the same project almost 12 years, it's easy to think that there can't be many surprises," Metsavainio told Insider. But catching the ghostly debris on camera, he said, was among the most unexpected elements of his Milky Way project.</p><div type="image" title="Cygnus Mosaic supernova remnant" height="1701" width="2709" msid="81658088" hostid="261"></div><h2>The images took 1,250 hours to capture</h2><h2><div type="image" title="J P Metsavainio observatory" height="1495" width="1152" msid="81660178" hostid="261"></div></h2><p>Metsavainio lives about 90 miles from the Arctic Circle and has a private at-home observatory. For six months of the year, the cloudless sky above his home is ideal for stargazing. He takes advantage of this winter period to observe objects via telescope and snap photographs of them. </p><p>"I work every single clear night," he said. </p><p>Metsavainio often stays up late, photographing in silence, he said. On a given night, he added, he can observe an object for four to seven hours, depending on its height on the sky.</p><p>He prefers to take pictures manually using a wide-aperture telephoto lens.</p><p>"I'm a perfectionist regarding my work," he said. "I don't want to miss a single valuable clear moment due to some small software glitch."</p><p>In total, he spent 1,250 hours collecting images for his Milky Way mosaic.</p><p>He stitched the individual images together in Photoshop, using stars as a guide to match the shots. His mosaic uses color coding to represent ionized elements lingering in the galaxy: red for sulfur, green for hydrogen, and blue for oxygen.</p><p>The final image shows several <keyword id="1684499" type="PERSON" weightage="60" keywordseo="nebula">nebula</keyword>e - clouds of dust and gas in which new stars form - in different constellations. Those include the California Nebula in the constellation Perseus, which is about 1,000 light-years from Earth, as well as the Cave Nebula in the constellation Cepheus, about 2,400 light-years away.</p><div type="image" title="california nebula" height="1026" width="1369" msid="81658096" hostid="261"></div><p>The mosaic also shows the first black hole ever discovered, Cygnus X-1.</p><p>But Metsavainio said the <keyword id="517558" type="COMPANY" weightage="60" keywordseo="supernova">supernova</keyword> remnants were his "absolute favorite" elements of the project. He called them his "three musketeers."</p><h2>The remains of one supernova took 3 years to capture</h2><p>A supernova is the <a href="https://www.businessinsider.com/longest-observed-supernova-explosion-annihilated-massive-star-2019-8">final explosion of a dying star</a>. It releases a massive amount of energy, scattering debris across the galaxy and leaving behind an expanding nebula.</p><p>Under normal circumstances, dust blocks our view of these structures.</p><p>"They all are extremely dim and in very dense star field," Metsavainio said. "That makes imaging almost impossible."</p><p>But after 300 hours of observation, he finally snapped enough photos to capture the three clouds of debris.</p><p>One structure in particular, the remnant of supernova W63, was a target of Metsavainio's for many years. It's more than 5,000 light-years away, near the constellation Cygnus - hence its nickname, "Cygnus Shell."</p><div type="image" title="Cygnus shell Supernova" height="1170" width="1560" msid="81658100" hostid="261"></div><p>Scientists haven't identified the original star that exploded to form W63, but they estimate that <a href="https://apod.nasa.gov/apod/ap181102.html">light from the explosion</a> would have reached Earth more than 15,000 years ago. </p><p>It took Metsavainio three years, from 2015 to 2018, to collect enough photos of Cygnus Shell alone. Capturing objects like this are "the reason I keep doing this slow and lonely work," he said. </p>

A stunning image of the Milky Way took 12 years to photograph. It shows the ghost of a supernova.

<p><div class="KonaFilter image-container display-table float_right"><div><div class="image on-image"><img src="https://static-ssl.businessinsider.com/image/545cf40f69beddcd2ac26637-731-548/hubble-image-light-echo-2.jpg" border="0" alt="hubble image light echo"><p class="source"><span><a href="http://hubblesite.org/newscenter/archive/releases/2004/10/image/a/">NASA and The Hubble Heritage Team (AURA/STScI)</a></span></p><p class="caption">"Light Echo" Illuminates Dust Around Supergiant Star V838 Monocerotis</p></img></div><p></p></div></div>Illuminate the universe and you'll see more beauty than you could ever imagine.</p>
<p>That's exactly what a cosmic phenomenon, called a light echo, does.</p>
<p>This Hubble image to the right was taken in February, 2004 and is a consequence of the revealing power of the light echo.</p>
<p>This isn't just a pretty image, though. It's one of many that <a href="http://www.businessinsider.com/hubble-images-show-universes-secrets-2014-10">the Hubble has caught that actually teaches us something new about how our universe works</a>.</p>
<p>We think it's one of the most stunning scientific images we've seen from the telescope because astronomers had to wait nearly two years for it.</p>
<p>That's because before 2002, the only thing we could see in this region was a supergiant star.</p>
<p>But in January 2002, the star, located 20,000 light years from Earth, gave off a blindingly bright pulse of light.</p>
<p>For the brief period of time the pulse lasted, the star was the most luminous star in our galaxy, shining at 600,000 times brighter than our sun.</p>
<p>The star eventually faded, but the light it emitted continued to travel outward, illuminating the star's surrounding nebula, as shown in the animation below.</p>
<p><div class="KonaFilter image-container display-table full"><div><div class="image on-image"><img src="https://static-ssl.businessinsider.com/image/545beb68eab8ea615d30c1bf/hubble1.gif" border="0" alt="hubble light echo"><p class="source"><span><a href="https://www.youtube.com/watch?v=U1fvMSs9cps">Our Universe Visualized</a></span></p><p class="caption">Animation of a light echo in action.</p></img></div><p></p></div></div>Between May 2002 to February 2004, Hubble snapped five images of the star, shown below. With each succeeding image, Hubble gave us a more beautiful look into this nebulous cocoon.</p>
<p><div class="KonaFilter image-container display-table full"><div><div class="image on-image"><img src="https://static-ssl.businessinsider.com/image/545bec3969bedd087af16fd0-1000-500/hs-2004-10-b-full_jpg.jpg" border="0" alt="hubble light echo progression"><p class="source"><span><a href="http://hubblesite.org/newscenter/archive/releases/2004/10/image/b/">NASA, ESA, H.E. Bond (STScI) and The Hubble Heritage Team (STScI/AURA)</a></span></p><p class="caption">Series of Hubble images showing a light-echo progression. </p></img></div><p></p></div></div>What we see if the result of starlight propagating through space and then reflecting off the nebula's gas and dust, just like sounds bounces off of walls in a cave creating an echo-effect. Some of that reflected light heads toward Earth and was detected by Hubble.</p>
<p>Below is a gorgeous simulation showing the full, gradual progression of the most stunning light echo we've ever witnessed.</p>
<p><iframe width="560" height="315" frameborder="0" src="//www.youtube.com/embed/U1fvMSs9cps"></iframe></p>

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It took over a decade and 1,000 hours of photography to create this picture of the Milky Way

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A stunning image of the Milky Way took 12 years to photograph. It shows the ghost of a supernova.

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