Laser Pointers in Stargazing!

Our fingers are great tools. We use them to eat, pick our noses, and of course, point at things. However when pointing at things in the sky, fingers usually aren't long enough. When one beckons at a star overhead to a friend, he/she often meets cries along the lines of "Where? Where? What? That one? WHERE?" Modern laser pointers have changed that situation.

Laser pointers are instruments capable of producing powerful beams of light, which can be seen scattering in the lower atmosphere, and make it easy to point out astronomical objects. Generally, astronomical laser pointers are green and more powerful than standard ones used for presentations and such. Even though red lasers are the standard and can propagate the longest distance without scattering, green lasers are preferred for celestial pointing. This is because the human eye is much more sensitive to green light than red light. These usually use a neodymium diode core as the main component of the instrument.

Generally, the units used by astronomers have a power rating of no more than 5 mW. Nonetheless, these can still be harmful if the beam hits the human eye directly. A standard pointing laser viewed at point blank range will appear brighter than the sun, and since the rays are aligned and coherent, they can cause severe damage to the retina. Industrial class lasers can blind you instantaneously. (Lasers can be pretty darn dangerous!) 

Another hazard of lasers arises from a rather ironic reason - pointing them at the sky. Celestial objects aren't the only thing you can see above you. The sky is 'inhabited' by aircraft flying overhead frequently. The risk of the laser beam hitting the eyes of a pilot or messing with instruments is extremely worrying, and could potentially lead to a disaster. Because of this, several countries have regulations regarding laser pointers, even requiring the people owning the higher power lasers to register with government authorities. There are cases of people who have pointed lasers at airplanes, been reported by the pilots, and subsequently been arrested. This is a serious issue. Clearly, with great power comes great responsibility.

Laser pointers are a wonderful thing. When used right, they can be extremely handy astronomical aids and help bring to the joy of astronomy to everyone.

THIS IS A 5mW GREEN LASER POINTER PRESENTED TO US BY ONE OF OUR CLUB FOUNDER, CEE!

Content writer: Venkatraman Srikanth (1st year, Nakshatra)