I’m glad you are. How about we plan on heading 12 million light years straight up into the Big Dipper? The spring sky is loaded with galaxies. When peer into the night sky this time of year, we gaze out and beyond the disk of our own galaxy the Milky Way into the depths of intergalactic space. Without the Milky Way in the way, there’s no limit to our vision.
To find the galaxy M81, orient yourself with this wide-view map, showing the familiar Big Dipper and North Star around 9 p.m. in late March. Each yellow circle represents the size of one field of view in a typical pair of binoculars. Created with Stellarium.
Many are arranged in groups called galaxy clusters. Even the Milky Way belongs to a cluster called the Local Group, comprised of over 50 members within a sphere of space having a diameter of some 10 million light years. The brightest members of our galactic neighborhood are the Large and Small Magellanic Clouds — only visible from southern latitudes — and the Andromeda Galaxy.
In this closeup map, the circles again represent the field of view of your binoculars. Navigating with binoculars is easier if you can steady yourself by leaning against a tree or building. Once you’re ready to go, start with the end stars of the Bowl and slew about two binocular fields to the left to find the bright galaxy M81. Look for a soft, misty spot. M81 should be visible in 7×35 and 10×50 binoculars from suburban and rural skies. Created with Stellarium.
Another nearby galaxy patch is called the M81 group, and it’s about 12 million light years away. Its brightest member is, you guessed it, M81. All the "M" objects are named after a catalog put together by French astronomer Charles Messier in the 18th century. M81 is the 81st entry in a listing of 110 clusters, nebulas and galaxies. It’s also a fairly easy galaxy to see in a pair of binoculars if you know just where to look.
To find it, you first need to know where north is. That’s easy. Face the direction of sunset, stick out your right arm and it will point due north. Next, find the Big Dipper, now high in the northeastern sky around 9 o’clock. M81 is about two binocular fields to the left of the uppermost stars in the Dipper’s Bowl. I’ve sketched two small asterisms in the maps — the triangle and "twig" — that are very easy to see in binoculars, and will help you reach your galactic destination.
One binocular field to the left of the "Twig" you’ll see a fuzzy little cloud — that’s the galaxy! If you study it closely, you’ll notice it has a brighter center. That’s the galaxy’s nucleus, where there’s a great concentration of stars. The very keen of eye may notice another fainter galaxy below M81. That’s M82, and it’s only 150,000 light years from its bigger brother, close enough for the two to gravitationally interact with one another. Astronomers have discovered tendrils of gas torn from both floating nearby.
Absolutely beautiful! M81 is called a grand design spiral because its spiral arms are so symmetrical about its hub. Our Milky Way is also a spiral galaxy, similar to M81. Photo: Jim Misti
M81 is one of the most beautiful galaxies in large telescopes and especially in photographs. Its graceful spiral arms can be followed all the way to the galaxy’s center. Most of its young, blue stars reside in the spiral arms while the older, redder variety are found in the hub. M82 is also a spiral but seen edge-on to our line of sight. Long exposure photographs reveal an incredible number of new star clusters inside its core, created from fresh gas funneled from M81 during a close encounter millions of years ago.
The interacting pair of galaxies, M81 (left) and M82 in Ursa Major (Big Dipper). Photo: Markus Schopfer
There are at least a half dozen more galaxies suitable for binocular viewing this season. As spring unfolds, I promise more of these little road trips to distant lands.
A heads up on the International Space Station (ISS) tonight (Thursday). We’ll have two passes over the region, the first starting at 7:32 p.m. in a bright twilight sky. Watch for the ISS to rise in the southwest, cut straight through Orion and move toward Leo the Lion in the east. The next is at 9:08 p.m. when it will cross the northern sky, cutting directly through the "W" constellation Cassiopeia.