October 2009

Tony Martinez

Each month I will describe sights of interest in the night skies of South Carolina. These sights will be broken down into three sections: what you can see with the naked eye, with binoculars, and with a small telescope. The best time to view the night sky is at and around the times when the Moon is not visible, what is known as a New Moon; which will occur this month on October 18^th. For October, your best viewing nights will be from October 9^th through October 23^rd. The Star chart below is set for Florence, SC on October 15^th at 10 pm.

Jupiter: As of this writing, there is still significant humidity present in the night skies. As I mentioned last month, October may give us some clearer viewing of the planet Jupiter. So keep trying to find the “perfect” night to view the clouds bands of Jupiter.

The Andromeda Galaxy: October and November are great months to view the Andromeda Galaxy, also known as the Andromeda Nebula, and Messier 31 (M31). The Andromeda Galaxy is 2.5 million light years away, and is the farthest object that the unaided human eye can see. It is also the closest spiral galaxy to our Milky Way. Most recent data show that it is twice the size of our Milky Way. Another interesting fact is that the Andromeda Galaxy is blue-shifted. You may remember the term red-shift. When an object moves away from us at very high speeds, the light we observe shifts toward the red end of the spectrum (Doppler Effect). Most deep sky objects show a significant red-shift, demonstrating that the universe is rapidly expanding. However, the Andromeda Galaxy’s blue-shift means that it is headed right at us, and present data shows that the Andromeda Galaxy will collide with the Milky Way in about 2.5 billion years. The speed that we are approaching each other is 190 mi/sec, or 11,400 mi/minute, or 684,000 mi/hour. So every day we get over 16 million miles closer to collision!

So how do you observe the Andromeda Galaxy? Since you know you can see it with the naked eye, use the chart below, or other charts on the Internet, and try to find the Andromeda Galaxy using only your eyes. It is really easy to see if you can get away from the city lights. The chart below on the left shows the southeast at 10 pm on October 15th. Start by finding the “W”, Cassiopeia, and then move right to the “Great Square of Pegasus,” and finally work your way down the long “V” of the constellation Andromeda. The image on the right shows how you may see the Andromeda Galaxy with the naked eye at a very dark viewing site.Next try to view the Andromeda Galaxy through a pair of 7 to 10 power binoculars. Using simple binoculars will allow you to see the Andromeda Galaxy, even with some city lights around. Most people who have seen the Andromeda Galaxy saw it through simple binoculars, or with low power telescopes, and it looks similar to the image shown below.

Now for some surprises: Let’s look at a typical professional astronomer’s image of the Andromeda Galaxy, shown below; wow!

Looking at the two images above, one would logically conclude that the galaxy is just so far away, that the binoculars are just not powerful enough to see the Andromeda Galaxy as the professionals can. So one day you may advance in your hobby, and invest in a more powerful telescope, maybe like our 10-inch Dobsonian. Then you crank up the power, look at the Andromeda Galaxy and surprise, it will be a little bigger, but it still looks similar to what you saw with your simple binoculars! At this point, you may be confused. Allow me to explain. Your binocular view as shown above, is not a distant view of a large galaxy; it is the view of the bright central core of a large galaxy. Even at 2.5 million light years away, a spiral galaxy measuring 200,000 light years across fills an impressive piece of the sky. Such an object would span at least seven Moon widths! Due to the low surface brightness of the Andromeda Galaxy, we don’t see the full diameter. If the Andromeda Galaxy was brighter, and our Moon passed near by, the image below is what you would see through your binoculars!

So, can you see the Andromeda Galaxy this large, (of course without the bright Moon in the way) using only amateur equipment; yes. First, stay away from high power, the galaxy is just too large; stay at 20 to 25 power. Next you need significant light gathering, so a small narrow refractor will not do. A large Dobsonian has a lot of light gathering, but it has too much power. Finally, if you can use two eyes instead of one, you will have even a better shot at success. All these suggestions add up to a 20 to 25 power pair of binoculars with 70 to 100 mm objective lenses as your best equipment to see the full expanse of the Andromeda Galaxy. The last requirement is out of your control, a clear night with a transparent atmosphere. If it is the “perfect night,” you might be able to succeed with just a pair of 7 or 10 X 50mm binoculars.

On a personal note: The image below represents the actual view I saw through my 25 X 100 mm binoculars in October 2003 at a campground star party only 40 miles north of the city of Philadelphia, PA. It was after a storm front had moved through, and it was indeed the perfect night. It was the only time in my life of viewing that I saw the entire Andromeda Galaxy.

Naked Eye Sights: Try for a naked view of the Andromeda Nebula.

Binocular Sights (7 to 10 power): The Andromeda Nebula. Jupiter’s moons.

Telescope Sights (60-100mm): Jupiter.

See you next month!

September 2009

Tony Martinez

Each month I will describe sights of interest in the night skies of South Carolina. These sights will be broken down into three sections; what you can see with the naked eye, with binoculars, and with a small telescope. The best time to view the night sky is at and around the times when the Moon is not visible, what is known as a New Moon; which will occur this month on September 18^th. For September, your best viewing nights will be from September 12^th through September 23^rd. The Star chart below is set for Florence, SC on September 15^th at 10 pm.

Jupiter: Although Jupiter was in opposition last month, this month should be a better month for Jupiter watching. First, Jupiter will rise earlier in the evening. Through most of the month, it will be in a good viewing position by 9 pm, and even better at 10 pm. Second, hopefully the humidity will lessen, allowing for clearer viewing. We always see the beautiful large images of Jupiter as I posted last month, but what can you expect to see through your own telescopes? The images below show two good views of Jupiter through amateur scopes. Remember, if you can’t see the cloud bands, it may not be a problem with your telescope, but it may just be a bad viewing night; keep trying.

Telescope Finding Scopes: I have mentioned finding scopes briefly in previous columns, but allow me to expand on this subject. 

Many of the readers of this column most likely have a telescope. All of your scopes have to be aimed at your target of choice. New amateur astronomers have to take the time and have patience to learn the night sky. Eventually you will be able to point to a spot in the sky and know that that is where M27 is, or the Hercules Cluster, or the Coathanger asterism, etc. However, no matter how good you become, you still have to be able to aim your telescope at your target. This should be a simple matter. Every telescope comes equipped with some type of “finding scope.” Traditionally, these finding scopes attach to the side of your scope, and are just small low power telescopes, usually 6 to 8 power, and they almost always have crosshairs in the lens to aid in locking the telescope on your target. Now the “problems”:  These small finding scopes usually give an upside down and reversed image, which may or may not match the image of your actual telescope. In addition, and probably the most frustrating is that in general, finding scopes give too small an angle of view. Note: In a small box, in my attic is every finding scope that came with every telescope I have purchased.

So how do you aim your scopes? There are two very effective aiming devices. The simplest and cheapest is a Red Dot Finder. The better and more expensive device is a scope mounted Green Laser.

First the red dot finder. The red dot finder does not use a red laser. It uses a red LED light. The LED is somewhat hidden in the back, and a reflection of the light is seen on a plain glass section in the front. As you look through the finder, you will see the red dot on the glass surface. You then simply overlay this red dot on the dark sky, and place it on your target of choice. The initial setup is best done in the daylight. Mount the red dot on your scope, aim your scope at a simple distant target, such as a street light or mailbox, etc and use the vertical and horizontal adjusting screws in the red dot to overlay the dot on the object seen in the center of your scope’s field of view. The red dot finder A below is about $38, and finder B about $65. Finder B has a larger field of view (not really necessary), and also has four different red shapes to overlay on the sky, which is a nice touch. (C below) There is another plus for the red dot finders. Usually, you don’t know exactly where you target is, so you place the red dot in the area where the target should be, and using charts, you search for the target. Once you locate the object in your scope, look through the red dot finder with both eyes open. You will now know the exact location of the object in the sky with the naked eye; this cannot be done with a traditional finder.

Second, the Green Laser Finder. The green laser has been a great tool for teaching astronomy. However, attaching a green laser to your telescope is also a great way to aim your scope. You can see exactly where your scope is pointing as you stand next to your scope and move it around; we use a green laser on our Dobsonian  telescope.  Allow me to describe a “trick” I use with the green laser. To locate a deep sky object such as the Dumb Bell nebula (M27), you point your scope mounted laser near the place in he sky where it is located based on your star charts, and turn it off. Next, use a pair of 7 or 10 power binoculars to find the object, and while holding the binoculars on the target, turn the laser finder back on and move the laser until you see the laser through the binoculars, “touch” M27. Your scope is now on your target. Note: This method is much easier to do with two people.

The complete laser and mount shown on the left below sells for $120.

Naked Eye Sights:  Enjoy Jupiter, and wait for someone to ask you, “What is that bright star?”

Binocular Sights (7 to 10 power):  Jupiter’s moons.

Telescope Sights (60-100mm):  This month and the next may give you your best views of Jupiter. Look for the cloud bands.

See you next month!