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.



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