In 2021, our galaxy, who’s Western name is the Milky Way, was mapped in a massive three dimensional panorama that detailed the contents of our galactic neighborhood and beyond. A mission of this scale required that the camera be almost one million miles away from Earth aboard Gaia, a spacecraft telescope. During Gaia’s 10-year lifespan, it gave citizen scientists a map of the stars so accurate that even from here in Alameda we can quickly find stunning space objects to observe and photograph.
Many of the star positions and distances we rely on to plan astrophotography today—including how we frame the focus of the article Messier 51 (M51)—are made possible by Gaia’s precise measurements. One example is plate solving, the process telescopes use to confirm exactly where they’re pointed. The telescope snaps a quick photo, compares the stars in that image against a catalog like Gaia’s, and adjusts its position until the match is perfect.
Gaia wasn’t an imaging telescope like Hubble or the James Webb Space Telescope—it didn’t take visual photographs. Instead, it mapped the positions, distances, and motions of more than a billion stars, giving us the most accurate star chart to date. Here on Earth, astrophotographers use this map to find and photograph celestial objects tens of millions of light years away.
In this series about astrophotography in Alameda, we will look at pictures of galaxies, nebulae, planets, and celestial events taken from our island. As we share information about these objects, please note that the science is up to date at time of writing, but thanks to telescopes like Gaia and Earthly observers alike, everything—all understanding of existence as we know it—is subject to change.
This first image in our series features two interacting galaxies known as M51, or the Whirlpool Galaxy. It is believed that the smaller galaxy (called NGC 5195) passed through the Whirlpool 500 to 600 million years ago. In space, it’s really hard to tell where objects are positioned relative to one another without extensive study. However, in the case of M51, it appears that the larger galaxy is physically in front of the other one. Look closely and you will see that the edge of the elongated spiral arm seemingly blocks light emitted from NGC 5195.
M51 is estimated to be 88% of the size of the Milky Way, and only 10% of its mass. The larger galaxy contains three supernovas (exploding stars) that appear as bright dots embedded in the spiral arms of the galaxy. In 2020, a potential planet was discovered within M51. If confirmed as accurate, it would be the first ever exogalactic planet—a planet outside of the Milky Way—to be discovered. While the two main galaxies steal the show, look again and you will see a third galaxy appearing like a small smudge in the upper right.
You’ll find details about the equipment used to capture this photo at the end of the article.
During this series, we will explore much of the equipment and techniques used to take these photos. M51 is 31 million light-years from Earth, but is so dramatically massive that its light penetrates light polluted urban skies. How is this possible? The answer is long exposure photography. Very, very long exposure. More than 11 hours of data were captured from the backyard to create this single image. This is achieved by combining hundreds of five- to seven-minute exposures.
What would you name this galaxy? Does it remind you of any landmark in Alameda? To me, it’s reminiscent of the ferry leaving Seaplane Lagoon in the early morning. As the catamaran backs out of the dock and spins around towards San Francisco, the blue water swirls like this galaxy. What does it look like to you?
Acquisition details:
- Telescope: GSO 6″ f/4 Imaging Newtonian
- Camera: ZWO ASI533MC Pro
- Mount: iOptron CEM25P
- Software: GNU Image Manipulation Program (GIMP), Pleiades Astrophoto PixInsight, ZWO ASIAir
While on vacation at Timber Cove in 2020, Evan Gomez-Shwartz accidentally photographed the Milky Way with his phone. Since then, he’s been taking photos of outer space at every opportunity possible, now with better equipment. The Alameda-based astrophotographer’s favorite subjects to photograph are nebulae and galaxies.
