I hope you saw the youthful moon last night. One observer left a nice report in the Comments section of yesterday’s blog. Because of another commitment I wasn’t able to see the moon but did catch Mercury just after 9 o’clock in the northwestern sky. It was very easy to see. Alas, the moon was too close to the horizon at the time and hidden anyway by a swatch of cirrus.
See the trio of moon, Mercury and the Pleiades tonight (Sunday) starting about a half-hour to 45 minutes after sunset. This map shows the sky as you look northwest around 9 p.m. Maps created with Stellarium.
Tonight promises to be another good one for moon and Mercury watching. The moon moves about one outstretched fist to the east (left) and upward each night, putting it comfortably above Mercury Sunday night. Joining the gathering will be the Seven Sisters (Pleiades) star cluster. While the cluster will appear faint, the moon and Mercury should be easy catches. Bring your binoculars to see all three at their best.
Mercury often appears pink when seen at twilight. When I was a kid, I remember thinking it was because the planet was really hot being so close to the sun. You may notice this too as you examine it with you eye. Truth is, it takes on the ruddy color of dusk. If you were to track down the planet during the daytime with a telescope, you’d see it as ordinary white, similar to the moon or Venus.
Mercury also has phases like our moon. Right now it’s a very tiny crescent that requires a telescope to see. Since we normally look at Mercury very low in twilight, the thick air at that elevation distorts and mushes out the image. That’s why some amateur astronomers choose instead to observe it during the day, when the planet’s much higher up and less disturbed by our roiling atmosphere.
See a planet in the daytime? Yes. The easiest way to do this is with one of those computerized telescopes, where you punch a button and the scope slews to its target. I don’t have one of these so I do it the hard way by plotting the planet’s position relative to the sun and moving the scope by hand. What can I say, it’s good exercise.
The supernova in NGC 4088 (NGC stands for New General Catalog) is near the Bowl of the Big Dipper. Here’s another picture of the galaxy. Photo credit: William Wiethoff
I spent much of the night observing comets and a pretty supernova in a galaxy called NGC 4088 in the Dipper. The supernova exploded 45 million years ago (the galaxy’s distance from us) but its light only finally arrived on Earth earlier this month. While a supernova looks just like a star superimposed on a galaxy, you have to remember that tucked into that faint point of light is the titantic explosion of a supergiant star at the end of its life. This one, called SN 2009dd, is smack dab on NGC 4088′s central core and bright enough to see in an 8-inch telescope from a dark sky. William Wiethoff of Port Wing was out last night too, and sent along the photo he took of the supernova. Gorgeous is all I can say.
The galaxy M102 (top) shows a thin lane of dust across its middle. Our galaxy the Milky Way shows a similar lane silhouetted along its length (below). Since we’re sitting right inside our galaxy, the Milky Way’s dust lane shows much more detail and texture. Photos: top, Will Wiethoff, bottom: Bob King
Will also photographed another galaxy called M102 in the constellation Draco the Dragon. Notice the dark line bisecting the glowing disk. We see this galaxy from the side or "edge on". From this perspective, stardust within the galaxy’s disk is silhouetted against billions of stars and appears as a dark lane. The same stardust is visible along the length of the Milky Way galaxy, where it looks like dark blotches among the bright starclouds. Much of this dust originates from the remains of exploding stars just like the one in NGC 4088. There’s poetry in that.