Galactic gifts from the Lawnchair Magi

From our vantage point, we’re privy to hundreds of thousands of extragalactic nebulae, some similar to our own and others not so similar.

The great majority of galaxies are spiral shaped and resemble our Milky Way, although many are viewed from different perspectives. We see some galaxies edge on, while some of the most awesome views are inclined face on from our perspective.

Like the clusters of stars we see in our own galactic neighborhood, galaxies congregate in similar groups, of which our own is a member. Belonging to what we call the local group, ours is one of the main members, along with Andromeda, sharing this special association with about 20 others.

This small group additionally belongs to the large grouping known as the Coma-Virgo Cluster. From backyard telescopes, members of this extremely dense population of galaxies can be peaked at under very dark, clear, moonless skies.

In this group, besides the edge-on and face-on spirals, there exist several irregular galaxies. Some are cigar shaped, while others seemingly have no specific shape at all, but rather are seemingly just massive conglomerations of stars.

For viewers in the Southern Hemisphere, the Small and Large Magellanic Clouds are representative of this latter type. Over the course of the next few million years, these satellite galaxies will slowly but deliberately be absorbed by the Milky Way.

For some actual terrestrial observing, I’d like to begin by steering your attention toward the easiest of all constellations to find: Ursa Major and the realm of galaxies that reside there. The Big Dipper contains a wonderful range of extragalactic targets, although you’ll need access to a telescope to see them in person.

Beginning with the handle of the Big Dipper, just below the handle’s end star, you’ll see the Whirlpool Nebula, or M-51, as it’s better known. Your best bet is to use a wide-angle, low-power eyepiece to first detect this very dim, yet expansive, galaxy.

However, as the Dipper stands on its tail at this time of year and just above the treetops, seeing through the atmospheric turbulence near the horizon may make viewing M-51 a bit of a challenge.

Of note, M-51, like the Milky Way and the Magellanic Clouds, has its own galactic neighbor, which seems to be in the process of being devoured by this very large spiral. To see it, let your eyes become very dark-adapted first, then scan this area of sky just below the tail star of the Dipper’s handle. At first, you may see what appears to be two bright spots, although as you use a technique known as averted vision, you just may glimpse a bit more detail.

(Averted vision: Looking away from a dim object, to the immediate left or right, can let the more sensitive sides of your eye detect what you wouldn’t be able to see looking straight on.)

The two bright spots you’ll see are the two nuclei of each of these galaxies. In the long-exposure photographs of M-51, the spiral structure and in-falling material from its neighbor become dramatically apparent.

Toward the other end of Ursa Major, up by the bucket’s end stars, resides a pair of galaxies known as M-81 and M-82. To find these, draw an imaginary line beginning from the bottom left star of the Dipper’s bucket up through the top right star and out into space about an equal distance. M-81 is the face-on spiral that’s slightly tilted back away from us. Its partner is inclined more in the edge-on perspective.

Each of these can be seen in amateur-grade instruments, although the larger, the better. They’re fairly dim, but can both be seen in a wide-angle lens.

Another easy target to find is M-109 just to the left and above the bottom right star of the Dipper’s bucket. This is another face-on oriented galaxy and is further distinguished as a barred spiral. It can also be viewed with a large backyard telescope, and given the right sky conditions, will provide you with a glimpse of the barring that gives it its classification.

Finally, another pair of galaxies, M-107 and M-108, are located a slight distance to the left of the bottom right star of the Dipper’s bucket. M-107 is also known as the Owl Nebula, sporting two owl-eye-like dark regions embedded in the glow of its countless stars. M-108 is another classic example of a face-on spiral galaxy.

There are many more galactic sights in and around the Big Dipper and throughout the heavens, as well. A favorite hunting ground for many enthusiasts is the area between Leo’s tail and Virgo. Here is where you’ll find tens, if not hundreds, of wispy splashes of light that are collectively known as the Coma-Virgo cluster of galaxies that I mentioned earlier.

This is the galactic group to which our smaller local group of galaxies belongs. Quite a menagerie of island universes, this relatively small area of sky is filled with very distant, and therefore very dim, nebulae, which astronomers have determined are part of the group to which our own Milky Way belongs.

Scan this area with a large instrument and low-power eyepiece and see how many of these galaxies you can count.

Leo, Virgo and the Coma Berenices constellations rise above the eastern horizon after midnight in December. Led by ruddy Mars, Saturn also returns to the early morning skies, tagging alongside the Coma-Virgo cluster below the back paws of the Lion. As the hours go by, these targets rise higher and higher off the eastern horizon and the turbulent air near the treetops.

Finally, another opportunity presents itself in December to add yet another honor to the Lawnchair Trophy Chest. Jupiter, high in the southern sky after sunset, is closely accompanied by Neptune (see map), making it possible to capture in person, even in small backyard instruments.

So, enjoy your time out under the skies in December while the planet continues its annual tilting until we reach the winter solstice on the 21st. Then the process reverses itself and days will actually start getting longer. Won’t that be nice!

As it gets dark quite early, you can also still see some of late summer’s finest sights before dinner, and then get a gander at what winter brings in the way of celestial presents under, or in this case, over, the trees!

Clear skies – although you may want to keep an eye out for reindeer at low altitudes!

Gerry Descoteaux, author of “The Lawnchair Astronomer,” is a freelance writer and teacher who has taught astronomy at America Online’s Online Campus for more than 10 years. His course, “Astronomy, An Introduction,” is presented on the Internet. He can be reached at gerry@thelawnchairastronomer.com or www.thelawnchairastronomer.com. His column appears the last Sunday of each month.