AstroBob has been a much better contributor to this blog than I have, but I will write a new post soon, I promise! -Rebecca
Amateur astronomer Bob Fisher (better known as AstroBob around these parts–much to his chagrin) has been a passionate star-gazer since childhood when he first saw the superbly dark skies of the Adirondacks on camping trips. A part-time resident of Olmstedville since 1991, he taught earth science and astronomy in New York City public high schools for more than two decades before making his permanent home here in 2006. Now a substitute teacher in Warren and Essex county schools, he is also an active astrophotographer. He frequently leads astronomy workshops in local schools and libraries.
DEEP SPACE, DEEP TIME
The springtime sky at night in April is not spectacular when compared to other seasons. In winter, about a dozen of the brightest stars visible in our area are concentrated in the East and South. On a clear cold night in January, the brilliant stars of Orion and Sirius in Canis Major (the brightest star in the sky), are truly awe-inspiring. In summer, at a site free of any light pollution, the Milky Way spanning the sky from North to South can take your breath away! With the exception of Arcturus and Regulus, the stars of April are relatively faint. Although the sky is relatively lackluster to the naked eye, we can gaze through a window into deep space and time, far beyond our galactic home.
At this time of year, our view is oriented out and away from our home galaxy, the Milky Way. As a result, we peer into deep space, far away from our nearest stellar neighbors. This is the realm of the galaxies. With a little optical assistance it is possible to see these massive rotating disks, each containing billions of stars. Despite their immensity, they appear as faint smudges of light even in large telescopes. Thus, astronomers affectionately call them “faint fuzzies.” At minimum, you will need a good pair of binoculars (10×50), or a small telescope with at least a four inch objective. Let’s have a look.
The best place to go galaxy hunting is in Ursa Major (The Great Bear). Face north and look for that famous asterism The Big Dipper. At around 10:00 P.M. it is nearly overhead, bowl and handle upside down. With patience and a good star chart, it is possible to spot 10 or more galaxies in this part of the sky. To increase your success in locating these faint objects, I would like to describe three of the brightest and most distinctive. But first, let’s discuss terminology and perspective.
In the late 18th century, French astronomer Charles Messier assembled a catalog of around a hundred faint, diffuse objects visible with his four inch telescope. In his honor, we begin the label of each of the brightest “fuzzy” objects with a capital M. M81 and M82 are a pair of galaxies, physically close to each other and usually the easiest to spot on a very clear night. At a mere 11 million light years away these are the closest galaxies to us visible at this time of year. The most common astronomical yardstick is the light year. It is a practical way to measure VERY large distances. For example, at 4.4 light years distant, the closest star to our Solar System is Alpha Centauri (a bright star visible only in the Southern Hemisphere). Light from this star travelling at 186,000 miles per second took four and a half years to get to us. That’s around 26 trillion miles. Considering the “nearby” galactic pair M81/M82 at 11 million light years distant, the distance in miles would be 6 trillion (for one light year), multiplied by eleven million. That’s a lot of miles! By the way, the latest estimate for the “edge” of the visible universe is 13.7 billion light years. Personally, my earth bound brain has a hard time getting any perspective or sense of scale for these “astronomically” large numbers.
Below is a detailed examination of a galaxy and two galaxy pairs that I photographed with my 8 inch f/4 telescope on March 20th and 21st from my wonderful dark sky site in Olmstedville,NY.
M81/M82 – At a mere 11 million light years away, the members of this galaxy pair are physically close to each other. M81 on the left of this photo is a large spiral galaxy in which powerful gravitational tides have churned up dust and gas in its companion M82, seen on the right. M82 has been nicknamed “the cigar galaxy,” because we are looking at its disc edge-on. This galaxy is a so-called starburst galaxy in which many millions of new stars are being created. The Hubble Space Telescope’s clear view displays spectacular red streamers emanating from its core.
M101 – At 28 million light years distant, this beautiful spiral galaxy clearly reveals the spiral arms that give it the apt nickname The Pinwheel.
M51 – The Whirlpool Galaxy – At 35 million light years away, this is a galactic pair. A spiral arm of the larger reaches out and connects to the smaller galaxy on the left of this photo.