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Friday February 24th 2017

Posts Tagged ‘astronomy’

Top 10 Night Sky Objects for Astronomy Beginners

Orion Nebula (M42), Image credit: Wolf DammYour first telescope has just arrived and now you can’t wait to try it out. Trust me, I remember this feeling very well. The universe is calling and it want to be discovered by you. There are so many exciting objects to explore. So, what to aim your telescope at?  I created a list of ten celestial objects that are great for beginners who own binoculars or small telescopes. The targets described represent different kinds of objects that exist in the universe. All objects are easy to find, and their size makes them equally suited for refractors, reflectors, catadioptric telescopes or binoculars. With the exception of the last listing, the Dumbbell Nebula (M27), all objects can be observed even with full moon.

Top 10 Objects for Binoculars and Small Telescopes

Top 10 Night Sky Objects for Astronomy Beginners A short version of the Top 10 Night Sky Objects can be download as PDF and printed. It is a one pager and serves as reference for the field. Links to constellation maps are offered for all stars and deep sky objects. I really recommend a planisphere for beginners; it makes it so much easier finding constellations at a certain day. Alternatively, SkyMaps offers a great monthly two- pager that shows all visible constellations and provides useful further information about current stargazing objects.  These maps are also free and can be downloaded as PDF.




MoonThe Moon is an ever fascinating object that can be observed almost throughout the year. Common presumption is that the moon can be seen best at full moon, but this is actually not the case. The best time is when it is a quarter or less. Sun light comes now from the side and moon features cast long shadows which render the telescope view almost plastic. It is most exciting to observe along moon edges and the Terminator, the line where the dark and illuminated areas come together.

The Moon came into existence when a Mars-size planet crashed into the early Earth. Fragments orbited the Earth and coalesced within just several weeks to become the Moon. The dark areas visible today at the moon are called Maria, from Latin “Sea”. They are meteorite craters that flooded with hot lava. Lava layers can be up to 10 km (6.2 miles) thick, higher than Mount Everest. Diameter: 3 476 km (27% of Earth)
Distance to Earth: 384 000 km (199,000 miles)
Mass: 7.350 x 10E19 tons (1.2% of Earth)
Density: 3.341 g/cm3 (61% of Earth)

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Jupiter is the fifth and largest planet in our solar system. It is a gas giant which is primarily composed of hydrogen and helium (very similar to our sun). Jupiter may also have a rocky core of heavier elements.

Jupiter is the largest planet in our solar system. It is a very bright and exciting object to observe. Four moons can be seen even with small telescopes or binoculars. If the conditions are good some cloud bands are visible, and with larger telescopes it might be possible to see some cloud details and the great red spot.

TIP: It is fun to draw the position of the moons and follow them over a period of time.

Click here for more information about the position of planets.

Jupiter is a gas giant with over 100 moons. The four largest are Io, Europe, Ganymede, Callisto. They are also called the Galilean moons. When Galileo saw the movement of the moons he could no longer accept a geocentric model of the universe. Diameter: 142 980 km (11.2 x Earth)
Mass: 1.899 x 10E24 tons (318 x Earth)
Density: 1.32 g/cm3 (24% of Earth)
Distance from Sun: 4.95 AU

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Saturn, Image credit: Wolf DammSaturn is probably the most enigmatic of all planets. Its rings have given awe to many people who saw it the first time. Since Saturn is double as far from the Sun than Jupiter, it receives only a quarter of the light. While it has almost the size of Jupiter, Saturn’s larger distance results in a smaller, fainter view in the eyepiece. We tend trying to compensate by increasing magnification, but this multiplies air layer disturbances as well. Unless seeing conditions are perfect, a good compromise is a magnification between 100 and 150.

With a very small telescope or under not so good seeing conditions, Saturn’s rings might just be seen as “ears”.  In fact, this is what Galileo saw when he first looked at Saturn with his telescope. He concluded that these “ears” must be two close moons on either side of Saturn, but two years later the moons were gone, and again two years later the moons re-appeared. We know today, that the “disappearance” was caused by looking at the ring edge on but it was very confusing for Galileo at that time.

Click here for more information about the position of planets.

Saturn is a gas giant, and has over 62 moons, with Titan and Rhea as the largest ones. Saturn has a very low density, in fact if we could build a bathtub large enough to hold Saturn, it would float on the surface. Diameter: 123 000 km (9.4 x Earth)
Mass: 0.569 x 10E24 tons (95 x Earth)
Density: 0.67 g/cm3 (24% of Earth)
Distance from Sun: 9.54 AU

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Mizar & Alcor

The Big Dipper is probably the best known asterism for stargazers in the Northern hemisphere. Big Dipper consists of seven stars and belongs to the constellation Ursa Major, or Great Bear. It is easy to find and its serves as guidepost to Polaris. Find the brightest two stars at the outer bowl edge, Dubhe and Merak. Take 5 times their distance and you reach Polaris, the Northern Star.

Mizar & Alcor
Mizar & Alcor (click on image for larger scale)

Big Dipper holds some surprises that are revealed at closer observation. Point your telescope at the handle bend and what you see are not one but two stars. The brighter one is Mizar, the dimmer star is Alcor. They are also known as “Horse and Rider”. People with good eyesight can distinguish these two stars with bare eyes. If the seeing conditions are good, choose high magnification and take a closer look at Mizar. You will see that Mizar itself has another close companion star.  The image above shows an actual photo of Mizar A, his close companion Mizar B and Alcor (click at the image to open a larger scale version).

Click here for a star map of Ursa Major.

The Mizar – Alcor system consists of even more stars that are however too faint for small telescopes. Four stars belong to the local Mizar system and the Alcor system consists of two. New research has revealed that both systems are gravitationally linked, making Mizar & Alcor a true 6-star system. Constellation: Ursa Major, UMa
Magnitude (Mizar/Alcor): 2.2 /4.0
Separation: 11.8′
Distance: 83 Light years
Mass (Mizar/Alcor): 7.7 /2 x Sun, Diameter: 4.1 / 1.8 x Sun
Luminosity: (Mizar/Alcor): 63 / 13 x Sun

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In the night sky: late Spring to Fall.

Albireo, HunterAlbireo is the fifth brightest star in the constellation Cygnus (Swan). With naked eye it appears to be single star but a telescope resolves it as double star. Both stars offer a striking color contrast. The brighter star shines in yellow color, the smaller star in blue.

Image credit: Hunter Wilson.

When observing colorful stars, it can be beneficial to do this somewhat out of focus. Since the star disks become larger, colors become more prominent. The reason for this is that a larger number of color receptors in the eyes can collect color information . Play with your focuser and see what works best for you.

Click here for a star map of Cygnus.

At this point it is unknown whether the stars are optical doubles or gravitational linked and orbiting each other.The brighter star itself has a very close companion, too close though to be resolved with a telescope. Constellation: Cygnus, CYG
Magnitude: A 3.2, B 5.8
Separation 35″
Distance 390 / 390 Light years
Mass: 5 / 3.2 x Sun
Diameter: 16 / 2.7 x Sun
Luminosity: 950 / 120 x Sun

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Orion Nebula (M42)

In the night sky: Winter and Spring.

Orion Nebula (M42)The Orion Nebula is part of the constellation Orion. This truly beautiful nebula can be found just below Orion’s belt as a part of Orion’s sword. It is one of the brightest nebulae and is visible to the naked eye.

Because M42 is over an arc minute wide use your lowest magnification to ensure it fits in the field of view. The four stars at its center are called “Trapezium”, they energize and ionize surrounding gasses which leads to this beautiful spectacle.  Due to its brightness the Trapezium stars draw the observers attention, but scanning the area around them, you will see many smaller stars and layers of ionized gas.

Click here for a star map of Orion.

Orion nebula is the closest region of massive star formation to the Earth. It hosts protoplanetary discs and brown dwarfs. New stars and planets are born here right now. The strong radiation emitted by the Trapezium stars is so powerful that young neighbor stars are pushed into the form of an egg. Constellation: Orion, ORI
Magnitude: 4.0
Size: 65’x60′
Distance 1,344 Light Years
Diameter: 24 Light Years
Mass: 2,000 x Sun

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Andromeda Galaxy (M31)

In the night sky: Summer, Fall and Winter.

Andromeda Galaxy (M31)The Andromeda Galaxy belongs to the constellation Andromeda. It is the farthest object that can be seen with bare eyes. It is so large that it will most certainly exceed the field of your telescope view (binoculars have sufficient viewing angle) Nevertheless is a fascinating moment taking a peak at another Galaxy for the first time. The core is very bright and the surrounding areas can be seen nicely.

There are many ways finding the Andromeda Galaxy in the night sky. My favorite is to extend the most pointy part of the Cassiopeia “W”three times.

Click here for star maps of Andromeda and Cassiopeia.

The Andromeda Galaxy is a spiral galaxy has an estimated 1 Trillion stars (Milky Way 200 – 400 Billion). Its center comprises a massive black whole. Andromeda Galaxy will and the Milky Way are moving towards each other. They will merge in about 4.5 Billion years. Constellation: Andromeda, AND
Magnitude: 3.44
Distance 2.54 Million Light Years
Mass: 1- 1.5 x Milky Way Galaxy

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Hercules  Cluster (M13)

In the night sky: Spring, Summer and Fall.

Herkules Globular Cluster, Image credit: ESA, NASAAs it’s name already reveals, the Hercules Global Cluster lies in the constellation Hercules.  The Globular Cluster is almost as old as the known universe and offers beautiful view even for small telescopes.

Image Credit: ESA, NASA

It is a bit more challenging to find Hercules Globular Cluster. First we have to find “The Keystone”, four stars of the constellation Hercules that build a trapezoid. M13 lies on the line between Eta Herculis and Zeta Herculis. These are the two stars in “The Keystone” at the side of Arcturus. Move a little bit towards Eta on the Eta-Zeta line and you have found this beautiful globular cluster. If you have difficulties to find “The Keystone”, two bright stars, Vega and Arcturus help. Draw a line from Vega to Arcturus, “The Keystone” is located about one third the distance from Vega.

Click here for a star map of Hercules.

Despite it’s age, Hercules Globular Cluster has not changed its form much. Pressure of star radiation pushing stars apart and gravity force pulling them together, resulting in an equilibrium. The stable conditions were thought to be beneficial for possible forming of life. In 1974 a radio message was sent to the Hercules Cluster with the large Arecibo radio telescope. The digital message included information about man, earth and the solar system. Constellation: Hercules, HER
Magnitude: 5.8
Distance 25,100 Light Years
Diameter: 168 Light years
Mass: 600,000 times Sun
Age: 14 Billion years

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Double Cluster (NGC 869 & NGC884)

In the night sky: Fall, Winter, Early Spring.

The Double Cluster (NGC 869 & NGC884), Image credit: Wolf DammIn his classic Field Book of the Stars (1929), William Olcott called the Double Cluster: “One of the finest clusters for a small telescope. The field is simply sown with scintillating stars, and the contrasting colors are very beautiful”. Does this not make anyone thrilled to observe this fine object? What we see are in fact two independent open clusters. They are about 800 light years apart but due to their position in the sky, they fit both in the view of a small telescope.

The Double Cluster belongs to the constellation Perseus. It can be easily found with the help of the constellation Cassiopeia. Just follow the inner leg of the shallow half of the “W” (Cassiopeia Gamma – Delta) about two third of the way to the next bright star, and you will find the Double Cluster.

Click here for star maps of Perseus and Cassiopeia.

The Greeks knew about the object as early as 130 BC, but the true nature of it was not discovered not before the telescope was invented.
The radiant of the Perseid meteor shower (Aug 12 & 13) is located in the neighborhood of the Double Cluster (SW).
Constellation: Perseus, PER
Magnitude: 4.2
Distance (NGC 869): 6,800 Light Years
Distance (NGC 884): 7,600 Light Years
Age (NGC 869): 5.6 Million years
Age (NGC 884): 3.2 Million years

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Dumbbell Nebula (M27)

In the night sky: Fall, Winter, Spring

Dumbbell Nebula (M27), photo credit: Wolf DammWith a magnitude of 7.5 , the Dumbbell Nebula is the faintest object in our Top-10 list. It is however the second largest planetary nebula in the northern sky and can be found relatively easily. The Dumbbell Nebula is located in the constellation Vulpecula, Latin for “Little Fox”. Vulpecula is a very small constellation with faint stars, southwest of Albireo in the constellation Cygnus. My preferred way to find M27 is with the help of the constellation Sagitta, the “Arrow”, just south of it. Its stars are brighter so they are easier to make out. They are shaped like an arrow with feathers (or a triangle  with tip). The Dumbbel Nebula, M27 is pretty exactly north of Sagitta’s tip star, Gamma Saggitae.

Click here for star maps of Vulpecula, Cygnus and Sagitta.

M27 is a planetary nebula. This term was coined by early astronomers who thought these nebulae were planets. In fact, they have nothing to do with planets. Planetary nebulae are clouds of material, shed by a star. It glows because it is excited by radiation emitted by a nearby object. Constellation: Vulpecula, VUL
Magnitude: 7.5
Distance 1,360 Light Years
Diameter: 1.44 Light Years
Central star
Dia: 0.055 Sun, Mass: 0.56 Sun
Age: only 9800 years

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Further Material

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Astrophotography – Without a Telescope

Milky Way, Credit: Ralph Clements

By Ralph O. Clements

When I was invited to write about this subject for, I must say I was flattered and a bit flabbergasted too, as I do not consider myself an expert on the subject, nor a writer by any means, but just a guy who likes to go out at night and take pictures of the sky. I stumbled into this hobby when my wife brought home an old 4” Meade reflector telescope with a manual equatorial mount from a yard sale that she paid $60 for.

I took that thing out in the country and set it up (completely wrong, I now understand) and as darkness approached, held my point-and-shoot camera up to the eyepiece and took a picture of Venus. Well, now that was very interesting…it was certainly not a very good photo and I have learned it is hard to get a good one of Venus, but I could tell it was not a star, it was not round but had a semi-circular shape. Wow! I took a picture of another planet! That got the gears turning in my head and I just had to do more….I mean who would think I could take a picture of another planet, with a point-n-shoot camera and an old yard sale telescope?

“Camera Only” Images

I do take images with newer telescopes and a decent equatorial mount which I have acquired since. Imaging galaxies and nebulae is an ongoing goal and interest, but I have learned that it is time consuming, tedious and has a fairly steep learning curve. My view of the sky at home is very limited. So for the time it takes to drive out to the country and get all that gear set up and working, I am limited to weekends and then only weekends when the sky is clear. Since clarity of skies does not always happen on Friday or Saturday night, I often image without the telescopes at all. All the tips and advice offered here is just what I have learned and I expect others may have better ways of doing things.


My research indicated that Canon cameras are preferred for astrophotography and the T1i is what I use for everything. I also have an older Nikon DLSR with two lenses, a 180mm fixed focal length and a 75-300mm zoom, for which I bought a Canon adaptor, but the 18-55mm “kit lens” that came with the Canon is what I use most often.

If you read up on astronomy and astrophotography equipment you will note it is often said that the mount is every bit as important as the telescope. My camera tripod is my mount and I fully agree that a sturdy tripod is a must. I am fortunate to use a tall Berlebach tripod with hardwood legs. The cheap aluminum department store tripods are not stable enough.

Figure 1: Orion at Peaks of Otter, Credit: Ralph Clements

Widefield & Star Trails

Camera only astrophotos with a static tripod fall into these three general categories:

Widefield – Single Shot

These include what would be considered “scenic” or “landscapes” in daytime photography, that is, including some portion of the Earth, as well as constellations and shot of the Moon (See Figure 1). I try to shoot as long as possible without having oblong or streaked stars. A high ISO setting helps with this and I often use 3200 ISO unless it is twilight or too much man made light is around. Figure 1, Orion and the Peaks of Otter, is a 10 second exposure and the stars are a bit oblong but not too bad.

Widefield – Stacked Images

Images that are composed of multiple single exposures, stacked and aligned in the computer to reveal much more of the faint light features than what is visible to the naked eye. Sagittarius (Figure 2) was taken as series of short, 6 second shots and stacked in the computer using Deep Sky Stacker. The exposure time for shot like this can vary depending on the target, its location in the sky and ambient light conditions. I find that targets nearer the poles may allow a little longer exposure than those on or near the celestial equator, which appear to move more due to their location.

Figure 2: Sagittarius, Credit: Ralph Clements

Star Trails Shots

Long Exposures or combined multiple exposures that show the apparent rotation of the stars above the Earth. Of course, the stars just appear to rotate because we are riding on the Earth which is really doing the rotating (Figure 3).

Taking star trails images is fun, easy and I like the look of them. Although a star trails image of say 40 minutes can be done on the “bulb” setting with a single exposure, this requires a remote timer and more importantly, a very, very dark site as the least ambient light will over expose the shot during that time. So I just take a series of 30 second shots and combine them using “Startrails” software, another useful and free program. This software is definitely easy to use and produces good results, although I do not notice much improvement when I use dark frames with it. For noise reduction I use “Noiseware Community Edition” in the final images instead. I recently became aware of another free software to do this, “Starstax”, and will be trying it soon as it offers more features.

On these star trails shots, sometimes it is good to have some moonlight on the subject and I will go out under a quarter to half moon and shoot them. I find a full moon makes it too much like daylight for my taste and if I lower the ISO under a full moon the stars don’t show up much. So depending on the amount of moonlight, artificial light and desire ground detail, I take these star trails shots at ISO setting of 800, 1600 or 3200. Generally, I try to get 40 to 60 minutes total exposure. Less than that and the trails are too short, more than that and chances are airplane will mess it up.

Figure 3: Startrails, Credit: Ralph Clements

Foreground and Framing

I try to pick a good site with some interesting foreground , although “fore-ground” in this case doesn’t mean close to the camera, rather, it means the part of the Earth that is shown.  I try to frame the shots so that the sky covers roughly ¾ of the frame, since the sky is the real subject and the foreground is really just a reference or point of interest.


To get crisp focus on the stars and the ground, anything in the image needs to be as far away as your camera’s “infinity” focus distance, which varies with the lens. So I try to take scenes that I would focus to infinity on if I were shooting them in daylight, such as the farm you see in Figure 3.  For all my images I use the camera’s “live view “. This feature lets me zoom in on a bright star, or the moon and focus. If your target is too dim, aim at a brighter one or an artificial light a long way off and focus on it and re-aim at your target. Make sure your camera is not set to “auto-focus”, use “manual”. The Nikon I was using did not have “live view” but I used the same method, only I looked through the view finder at a bright star or light. Sometimes a few test shots were needed to get it right.   

Getting Started

As for general advice for other beginners, I offer the following

  • Read your camera’s instructions, particularly the section on manual control.
  • Learn to work your camera’s controls in the dark, the corollary of which is….
  • Don’t be afraid to experiment. I use the trial and error method, with lots of trial and plenty of errors. That’s okay though as I am having fun and try to learn from my mistakes, and I don’t have to buy film for a digital camera, so I don’t mind deleting the ones that didn’t come out. 

….just do it! Have fun with it.


Further Reading


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Getting Started

So you think you are interested in amateur astronomy. Well, you are not alone. Every one of us who has become “hooked” on our hobby started out right where you are now. Hopefully we can get you started in such a way that you will find our hobby interesting and rewarding.

Most beginners get involved in amateur astronomy because they have looked up at the majestic night sky and found it fascinating. We have all marveled at the beautiful images from the Hubble Space Telescope. Just remember, if you expect to see images like those from Hubble, you are going to be deeply disappointed. After all, if we amateurs could see “stuff” just like Hubble, NASA would never have spent billions of dollars putting the observatory into orbit.

First of all, and this is extremely important:


There are lots of telescopes out there and some are total junk. So do not go out and make a major purchase that could very well disappoint you once you gain additional experience.

If you have not already done so, stretch out in a lawn chair and look up at the night sky. You will be amazed what you can see on a clear dark night just by “looking up”. Most people have binoculars so try using them from the lawn chair, you will see even more. Just scan the sky and look for areas of interest. The moon is visible almost every clear night of the year. Look along the “terminator”, the region between the light and dark parts of the moon. This is where you will find the most visible detail. Light pollution (along with clouds) is the biggest adversary for observers. If you live in an area where there is a lot of light pollution, try going out into the country where the sky is much darker. State Parks are a great place to view the night sky and you will see a lot more. - free monthly skymaps with explanation of interesting objectsAs you gain observing experience you will want to learn more about “what’s up” in tonight’s sky. Most people know about constellations, but which ones are currently visible? Will I even recognize them if I see them? What are the names of the bright stars that I can see? Are any of the planets visible tonight? Are there any Deep Sky Objects (DSO’s) that I can see? To answer these questions, and many more, you will need a roadmap of the sky. These roadmaps are called sky charts and planetariums. A simple free version of a sky chart is available online at

Have you ever wondered how a telescope works? Is it just plain old magic? Nope, there is a real reason that we can see all of those objects in space that are so very far away. If you would like to know more, take a look at This site does a great job of introducing the beginner to the kinds of telescopes that exist and how they work.

Find an astronomy club in your neighborhood and visit them at their public nights and star parties. You will meet great people who are glad to talk with you about astronomy and equipment, and will be glad to show you celestial objects with their telescopes.

Once you have attended some astronomy events you will discover that there is a lot more to amateur astronomy than you ever thought possible. You may have even found out that your real area of interest is not what you thought it was. Hopefully you have had the opportunity to view through various types of telescopes (and other observing tools) that are available. You may have even decided what type of telescope best fits your interests. You have been introduced to a whole new vocabulary of names and terms. You have found additional sources of information including books, the Internet, monthly publications and computer software (just to name a few) that will allow you to continue to learn about your new hobby.

Yet you have just scratched the surface. Amateur astronomy is a lifelong pursuit and the only regret that many of us “old timers” have is that we did not start it early enough in our lives. For many, amateur astronomy is a family happening. Regardless, now is the time for you to really get started.

Posted with friendly permission of : Indiana Astronomical Society


Further Information:

  • Sky & Telescope Guide: Getting Started in Astronomy for Northern Hemisphere or Southern Hemisphere. Great free pdf guide from Sky & Telescope. It offers valuable tips and advise for astronomy beginners, and it comes with bi-monthly star charts as well as a map of the moon.


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Solar Dynamics Observatory

Solar Dynamics Observatory 2017-02-24T19:37:15Z
Observatory: SDO
Instrument: AIA
Detector: AIA
Measurement: 171

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