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Wednesday November 22nd 2017

Posts Tagged ‘amateur astronomer’

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.

 

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Moon

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.

Facts:
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

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.

Facts:
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

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.

Facts:
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.

Facts:
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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Albireo

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.

Facts:
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.

Facts:
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.

Facts:
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.

Facts
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.

Facts:
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.

Facts:
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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A Telescope for under $100

Refractor 70mm on alt-azimuth mount
Refractor 70mm on alt-azimuth mount

This article is for people who are in the market for their first telescope – but have only a very limited budget (say $100) at their disposal. Some amateur astronomers will say spending $100 on a telescope is wasted money, simply because there is no great telescope for that amount. Good optics is expensive, but not everyone has hundreds of dollars to spend and there are indeed some decent telescopes that are fun and do not break the bank. A tight budget should never prevent anyone to start a fascinating hobby. 

Telescopes are available in three basic types: refractors, reflectors and catadioptrics and they come with different mounts. An Astronomy Source article “Introduction to Telescopes” in coming soon. The link from souledout.org  provides also a nice overview on telescope types.   

What can you see with a beginners telescope?

Quite a lot. I heard people complaining that the view through their basic telescope did not reveal bright and colorful images. Well, do not expect Hubble quality images with a $100 telescope. Suitable objects for these telescopes are the moon, the bright planets Jupiter and Saturn, some of the brighter deep space objects, and stars. Observe  Andromeda Galaxy (M31) or Orion Nebula (M42), you can also see the famous Hercules Cluster (M13). Stars shine in different colors due to their different temperatures and consistence, and there are many exciting double or ever multiple star  systems to watch. Did you know that Polaris, the North Star,  is actually a 3-star system? 

When looking for a budget telescope, keep in mind:

  • Do not consider department store telescopes that come with a ton of accessories, parts and pieces, and promise magnifications of whopping 500x or even more. These items are usually toys. There is nothing wrong with toys, but really, don’t expect clear images or lasting fun and excitement with those. What you can expect is inferior optics a lot of plastic parts that will break soon.
  • Glass lenses. Plastic lenses simply do not deliver the view quality of well polished and adjusted glass lenses.

New versus used

  • Telescopes can last very long if they are treated well. Used scopes are often available for half the price of a new one and many astronomers choose to buy used, simply because they want more: for the same money they get a much better (used) telescope, offering better images.
  • Be very careful buying a telescope at a yard sale. You may get lucky and find the deal of the century. More likely is however that the item is in a bad shape, because it has been neglected over years.
  • However, used equipment sold by serious amateur astronomers is usually in pretty good condition. True astronomers care about their equipment. A good source buying used telescopes and accessories is www.cloudynights.com. Check their classifieds and see what it offered here. Sellers describe their items in detail and provide usually very reliable information about the condition of their goods. Look for other dedicated astronomy sites that offer classifieds.
  • If you decide to buy used, you should wait – and be quick. This sounds like a paradoxon, but you should watch the classifieds for a while to get a feeling about a fair market price of  the the item you have in mind. When you see the right one, be quick to get it. Good items are often sold within a couple of hours. 

Further items for amateur astronomers:

  • Planisphere. Easy to operate map like device, that shows you where stars, constellations and planets are – all year long.
  • Red Flashlight. Eyes adapt to the dark, this is called night vision. Night vision takes a while, about 15-30 minutes, but allows to see much more and much fainter objects in the dark. Exposure to bright light, with the exception of red, erases light vision immediately and it takes another 15-30 minutes.
  • A good  astronomy book about telescopes and star watching gives helpful hints for the beginner and advanced astronomer.

Conclusion

Beginning astronomy is the start of a great, very exciting and fun hobby. A simple 70mm or 80mm refractor on alt-azimuth mount is probably the best choice as starter telescope for around $100. These telescopes are very easy to set up and simple to operate – just point and see the universe.   

 Further reading


  

 

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Astrophoto Gallery

This gallery shows astro-photos made by amateur astronomers.  Clicking the images enlarges them to original size and provides information about the object and how the photographs were taken.
Remember: Astronomy Source provides how-to posts about astro-photography. So far available:

Enjoy the images and do not forget to share comments and ideas.

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Helio Now

Solar Dynamics Observatory

Solar Dynamics Observatory 2017-11-22T09:14:45Z
Observatory: SDO
Instrument: AIA
Detector: AIA
Measurement: 171

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