Backyard Astronomy - Gazing Into The Past

Astronomy continues to be one of the more popular hobbies. One of the major reasons is because you can stargaze just about anywhere. Although country settings away from city lights are best, everyone can see the moon. And even though the closest star (after our sun), Alpha Centauri is over 4 light years away, can be seen easily with the naked eye.

While simple stargazing with the naked eye is great fun, using a telescope can be awe inspiring. The view of the heavens through even a small telescope is something that has to be experienced to be appreciated. Even though modern technology allows us to view the celestial realm with images on tv and through the internet, there is nothing quite like seeing it though a telescope.

Different Telescopes

There are basically three kinds of telescope. The refractor and reflector and catadioptric. The refractor telescope collects and bends light with a convex lense and eyepiece. This bending or refracting concentrates the light rays to a small focal point making things appear larger or brighter. The reflector telescope on the other hand, as its name suggests, reflects light from a convex mirror in the back of the telescope to another mirror in the front and finally to the eyepiece. The convex shape of the mirrors "scoop up" and concentrate the light to a focal point thereby magnifying an object. Caution: Objects in a telescope appear closer than they really are!

The third type, called Catadioptric, combines features from both reflecting and refracting telescopes.

Which one is best? For image quality and portability, my choice is the catadioptric. It's easily transported and has the best features of both the reflector and refractor telescopes. Because of the design, catadioptric telescopes are almost completely free of the coma found in reflectors and the chromatic aberration in refractors. Chromatic aberration is the distortion of color due to a lenses inability to bring various colors in the light into focus. Coma is the distortion of an object at the edge of your field of view.

Convenience is another factor to consider. If you have to transport your telescope as I do you'll appreciate the catadioptric's compact size, light weight and how easy it is to set up and take down.

Travel Through Time

We all know light travels at an unimaginable speed of 186,000 miles per second. Even our sun's light takes about 8 minutes to reach us once it's left the surface. Now think about our closest neighbor, Alpha Centauri. It's over 4 light years away so the light from its' surface began its' journey over 4 years ago. We are actually seeing it as it was more than 4 years in the past. In a very real sense we are looking back in time. Think back to what you were doing 4 years ago. Whatever it was, while you were doing it, light eminated from the surface of Alpha Centauri and came screaming along at 186,000 miles per second on the long journey toward earth, arriving here just a few minutes ago. Alpha Centauri is actually part of a star system. 3 separate stars, Alpha Centauri A and B form a binary while Alpha Centauri C is 13,000 Astronomical Units (AU) away. This is part of the reason it's easily seen with the naked eye, you are actually looking at 3 stars instead of 1.

Closer To Home

One need not look outside our own solar system to find amazing sites in the night sky. The moon may look smooth when seen with the naked eye but train a telescope on it and prepared to be wowed. The level of detail will depend on your telescope but the craters and jagged mountains are clearly visible. The best viewing, in my opinion is when the moon is in a crescent stage as the shadow created by the earth allows for much more detail to be seen. I saw the moon for the first time through a telescope years ago. I watched as it slowly drifted past my field of view and could almost feel its' movement. Of course I knew it moved along its' orbit around the earth but to actually see it moving was an incredible experience.

Saturn, probably the most fun to observe because of the rings, makes for spectacular stargazing. Depending on the time of year, the rings of Saturn are visible and to this observer, quite breathtaking. While I couldn't discern any colors or variations in the rings, they appear quite distinctly from the planet itself, something I'd seen only in books prior to that.

Stand on the shores of any ocean on earth and get a sense of the sheer enormity of it. Then realize that it's not even a drop in a bucket by comparison to the size of the sky it sits beneath. Looking up at the stars at night makes you realize just how massive everything really is. There is no number that can truly measure or even estimate its' size or dimensions. The only thing that can even remotely compare to the wonder of space is the imagination of those who view it.

Ron Berry is a freelance journalist who writes for Essay Street Article Directory and operates ScopeDoggie.com - The universal choice for telescopes online.

Astronomy, Star Gazing, and Green Laser Pointers

There is nothing more frustrating in astronomy that than unsuccessfully trying to identifying an object in the night sky to a companion by waving your arms, pointing fingers, describing and gestulating. An elegant, simple and very effective solution to this problem is to use green lasers pointers to point out objects in the sky.

Green laser pointers are high technology gadgets that are becoming more and more popular in astronomy. Not only are green laser pointers ideal for pointing out celestial objects, they are also very useful for aligning telescopes and for atrophotography.

Why green laser pointers

Green laser pointers are the preferred laser pointer color for astronomy because green is the most visible laser pointer color. The reason why green is more visible is the human eye is most sensitive to green light. The other reason is the effect of light in the earth's atmosphere. Light is visible in the sky when the atmosphere scatters it and higher wavelengths are scattered more than higher wavelengths. Green is a medium wavelength so it scatters more and is more visible than longer wavelengths such as red.

Other applications

Using green laser pointers to point out celestial object to people next to you is not the only application for laser pointers in astronomy. A green laser pointer can also be mounted on a telescope using a bracket or by holding the laser by hand in the groove parallel to the telescopes optical axis. The green laser pointer beam clearly shows where the telescope is pointing and the object being viewed through the telescope.

A green laser pointer mounted on a telescope can also makes aligning the telescope to a celestial object much faster and easier.

How powerful should the laser pointer be?

Green laser pointers can range in power levels from 1mW all the way to 200mW so deciding which power level to use can be tricky. The points to consider when choosing the power level for an astronomy laser are

-The number of people star gazing with you. If it is just one person, a low power such as 5mW will be suitable. If you are stargazing with a large group of people who will not be standing next to you, the laser needs to be more visible so a high power level such as 100mW would be suitable.

-The level of ambient light. If you are stargazing at dawn/dusk, during a full moon or in built up areas where there is a lot of light pollution, a low powered beam such as 5mW would be harder to see. You would generally need at least 50mW or more in this kind of situation.

Higher powered laser pointers are not always better because any glare from them can easily ruin your night vision and can provide a distraction. Many stargazing nights have been ruined when people have been paying more attention to the new and exotic high power laser used to point out objects than the actual objects themselves.

Caution

Deliberately pointing a laser at aircraft is a very serious offence in every country so avoid star gazing near airports and do not use a laser when there is an aircraft in the section of the sky being viewed.

Article is courtesy of Dragonlasers - No 1 lasers, laser pointer and green laser online store.

Frank is from Dragonlasers at http://www.dragonlasers.com