M67
Last time we took a look at M44, the Beehive Cluster, in Cancer. But M44 isn’t Cancer’s only cluster worth seeing. There is also M67, just a little to the south. At magnitude 6.9, it makes a very nice telescopic target. One difference between M67 and Cancer’s more famous cluster is that M67 is about six times as distant. With Mars still in the area and showing up nicely, this is still a very interesting part of the sky.
M44 in Cancer
For the amateur astronomer, few things can match the beauty of a densely packed open cluster. One of my favorites has always been M44, the Beehive Cluster, in Cancer. With it’s brightest star at magnitude 4.2, Cancer is a rather dim constellation and not always obvious to the backyard astronomer, especially when light pollution is an issue. But as can be seen on the map, Cancer is located between the easily found constellations of Leo and Gemini. Also currently passing through that area is Mars. So don’t forget to crank up the magnification and see how much surface detail you can see on the red planet.
Despite being one of the closest star clusters, there is some disagreement about the exact distance to the Beehive Cluster. Current estimates range from about 520 to 610 light years. Being this close means it appears both large and bright (at magnitude 3.1, visible to the naked eye under dark sky conditions.) And so it is best seen with low magnification. A good pair of binoculars would work well, otherwise use the lowest power eyepiece you have.
On these cold winter nights, just a little southeast of Orion, is a dazzlingly bright star - the brightest one in the night sky. Officially called Alpha Canis Majoris (designating it as the brighest star in the constellation Canis Major), it is better known as Sirius or the Dog Star. While the intrinsic luminosity of Sirius is about 25 times that of the sun, much of it’s apparent brightness comes from it’s close proximity to our own solar system. At a distance of 8.6ly, it’s just down the street in interstellar terms.
Although it can’t be seen by the backyard astronomer, Sirius has a small white dwarf compainion star called Sirius B. Due to it’s brightness, Sirius itself often appears to twinkle more than most stars, often flashing a variety of colors. So if you see that bright star in the southern sky this winter, you know it is indeed Sirius.
It’s already started, and it peaks on December 13-14. It’s the Geminid meteor shower. The Geminids are a very reliable meteor shower known for their multi-colored display. They would probably be everyone’s favorite meteor shower if they didn’t happen in December. But the cold temps (it was -6 here last night) tend to freeze the desire to go out and watch them. The Geminids are caused by 3200 Phaethon, an object believed to be the core of an extinct comet. The moon won’t be a problem this year, so if you can do it without freezing too badly, go out and enjoy the show.
M33
It’s getting to the time of year where a heavy coat and thermos of coffee are essential astronomy equipment. The last few days have really started feeling like winter in my part of the world. But if you brave the cold and venture out, the winter sky holds some real treats. One of them is the galaxy M33, the Triangulum Galaxy. There are times when, because of it’s appearance, M33 is called the Pinwheel Galaxy. However the name Pinwheel Galaxy officially refers to M101 - itself a worthy telescope target in the constellation Ursa Major. At magnitude 5.7, M33 can be seen with the naked eye if skies are sufficiently dark. Even under moderate light pollution, it makes a good telescopic target with a low power eyepiece. Being about 3 million light years away, M33 is part of the Local Group of Galaxies. It’s nearly face on view gives a great view of M33’s spiral structure. So heat up the coffee and take a look.
Finding M33 in Triangulum
The Pleiades
It may be known to science as Messier 45, but throughout history the Pleiades has gone by many names, including the seven sisters and the Maia Nebula. Subaru is the Japanese name for the Pleiades. The Arabic name is al-Thurayya. The ancient Hebrews called it kimah, and it is mentioned in the Bible. It is also important in Hindu mythology, where it is known as Krittika. If I wanted to, I could go on for a while with this list of names, as nearly every ancient culture has it’s name for the Pleiades. But I think you get the idea; people have been looking at this star cluster for a long time. And now we’re getting to the time of year where you can too. The Pleiades are in the east, in the constellation Taurus, in the late evening. Clearly visible to the naked eye as a bright patch, a good pair of binoculars are the best way to enjoy the cluster as a whole. A telesope will probably have too much magnification to see the whole thing at one time. However a good telescope will let you see the nebulosity surrounding the hot blue stars found in the Pleiades.
One of the reasons the Pleiades is such an obvious and easily visible cluster is because, at 440 light years, it is also one of the closest open star clusters to Earth. This makes it a little odd it was ever included in Charles Messier’s famous catalogue. Back in Messier’s day, finding a comet was the way to become famous as an astronomer. And so Messier catalogued objects that could be mistaken for comets. But it seems very unlikely someone would make that mistake with such a well known star cluster. In any event, if you’re trying to see how many Messier objects you can spot, this is about the easiest one out there.
Now that we’ve made the turn into November, we can start looking forward to this month’s famous meteor shower, the Leonids. Created by the comet Tempel-Tuttle, the Leonids will reach their peak on the 17th and 18th. And there’s no need to worry about the moon interfering with your viewing. While you’re up watching the Leonids, you’ll probably also notice Mars. The Red planet is rising in the east in the early morning hours, and will be shining at a bright magnitude 0.2 by the time of the Leonids.
Why look at one star cluster when you can see three of them? In the constellation Auriga, now showing up in the East around midnight, three moderately bright, but densely packed open clusters line up very nicely. The stars of Auriga are quite bright, so the pattern of the constellation should be easily visible. In the right side of that pattern, a line of stars (circled in yellow on the map) is faintly visible to the naked eye, and easy to spot through a finder scope. Follow the line of these stars to the left, and very quickly you’ll come to the first of these clusters, M38. Once you’ve found M38, start scanning down and you’ll find the other two clusters, first M36 and then M37. All three clusters are between magnitude 5.6 and 6.4 in brightness, with a large number of stars making each a telescopic treat.
These nights, if you stay up late enough, the easily recognisable constellation Orion is visible. And on October 21-22, this constellation is the radiant of the annual Orionid meteor shower. While the Orionids aren’t one of the better known meteor showers, everyone has heard of the comet that creates them. It’s none other than the famous Halley’s Comet. The rate of meteors is quite small for this shower, about 10 to 15 per hour. But it is known to sometimes produce spectacular fireballs. And the good news is that this year the moon shouldn’t cause any problems with viewing.
Well, not really. After all, despite being a self-described super-genius, good ‘ol Wile E. is a coyote … and fictional. But still, if the cartoon canine somehow could take over a NASA mission, and if he somehow suspected the Road Runner was on the moon, the result would probably be something along the lines of what’s going to happen Friday morning. Starting at about 7:31 a.m. EDT, NASA will continue it’s “let’s smash stuff open and see what’s inside” method of exploration by having it’s LCROSS mission impact the moon, not just once, but twice. First the LCROSS (Lunar Crater Observation Sensing Satellite) will separate from the empty Centaur rocket stage that helped send it on it’s mission. The rocket stage will be sent crashing into the lunar crater Cabeus. The LCROSS itself will be close behind, first monitoring the results of the Centaur impact, then impacting itself. The purpose of all this is to look for signs of water ice near the lunar south pole. Such a find could be a great boon to future manned moon missions. If you have a backyard scope ten inches or larger in diameter, you may be able to see the debris plume kicked up by the impacts yourself. Check out this SPACE.com article for more information on when and where to look.
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