Laser Pointers for Astronomy

Laser pointers are helpful tools for presentations and in the classroom but they can also be powerful instruments for astronomy as well. The right kind of laser pointer can cut through the night sky and paint the heavens. Astronomy laser pointers can be very useful for novice and advanced astronomers alike.

What’s In a Laser?

Contrary to pop culture portrayals lasers are not death rays or plasma cutters, they are just concentrated light. The laser was an acronym: Light Amplification by Stimulated Emission of Radiation. The acronym is outdated but the name remained and remains today.

Lasers are just powerful beams of focused light that are used to highlight things from a great distance. They can be used to highlight something on a presentation screen from a couple of dozen feet away to the Orion constellation thousands of feet above the Earth. They come in various colors and power levels for different purposes.

Lasers are formed using a laser diode. These are similar to other light diodes, like LEDs and produce light when electricity is applied to them directly. A power source, a focusing mirror, and a laser diode are used to form the basis of most simple laser pointers to great effect.

Despite the many options of color and brightness many astronomers and stargazers typically use a green laser pointer to point out objects at night. Red is the most common color for laser pointers, so why green?

Mean Green Laser Machine

Lasers can come in a variety of colors, red, blue, purple, orange and green. Green lasers are used for night sky purposes far more than other laser colors for a few reasons.

First, red light is one of the hardest kinds of light for humans to see. It is extremely unobtrusive due to its proximity to the infrared spectrum which humans cannot see at all. This is why darkened spaces are lit by red light in split shift situations.

Go Green

Comparatively, the green light is much easier for human eyes to detect. It is much sharper and does not get dispersed as easily as red light. This means when lasers are shone into the night sky, a green laser has a much lower chance of being dispersed by things in the air and allows the beam to travel a lot farther.

In a small room such as a conference room, atmospheric conditions will not affect the quality of a red laser pointer but when you want the beam to travel a lot farther, the color of the beam matters more. Even at low power green beams will travel much farther and keep their strength over red lasers.

This makes green lasers the optimal choice for people looking to point out interesting features in the night sky for their family, friends or students. Other lasers could be used but they will not be as effective or as consistently visible as a green laser in the same conditions.

When a green laser is pointed at the sky, is the light reaching to the object in question? No, the laser cannot reach as far as it appears on a night sky. The human eye follows the beam for as long as it can before the top is lost into the sky and it makes it appear as if the laser is pointing directly at objects that are millions of miles away.

This optical illusion is extremely neat to see and is one of the reasons amateur astronomers use them in their pursuits. So what exactly are these lasers used for?

Astronomical Laser Uses

The most basic use for a night sky laser is to simply point to objects in the sky. Just as someone would point to something during a PowerPoint presentation, a green laser can be used to point at the moon or specific stars in the sky.

This can be used for a single person to pinpoint specific stars using a star chart or app. This is helpful for someone who is trying to memorize and map the sky for future use. Knowing the position of major stars, planets, and galaxies in the night sky is extremely useful knowledge to any stargazer.

Lasers can also be used to point to objects for family or students. Due to the coherent appearance of the green light at night, the laser pointer is very useful for showing a group of people a specific point in the sky. This is useful for someone who is trying to show their kids or teach a class on astronomy or stargazing.

Lazer Telescope Mounts

Similarly, laser pointers can be mounted to telescopes to make stargazing more precise. Anyone who has used a telescope, especially a powerful one, knows that it can be easy to get lost in the night sky. The smallest movement or adjustment of a powerful telescope will cause a user to lose their bearings amongst the stars and without a guide, it can be hard to reposition on the desired object.

A telescope mounted laser can be used to precisely focus a telescope onto an object or area of the sky. This will make it a lot easier to find specific objects in the sky with the naked eye. Just like pointing out a star to another person, the laser can be used to point out specific things to the telescope and user.

Additionally, some lasers can be used in conjunction with computerized or motorized telescopes to allow the telescope to automatically find objects and track them in the night sky. These are generally found in more advanced or scientific telescopes for that laser-guided touch.

Important Information Regarding Laser Pointers

Laser pointers are very useful and extremely neat devices, however, they are not toys and come with considerable risks. Anyone needs to know the ins and outs of the risks involved with laser pointers and their use.

Laser pointers are grouped into four tiers based on their power and brightness:

Class TypePower Effects
Class 1Harmless
Class 2 Visible laser light, harmless if accidentally exposed to eyes
Class 3Safe if used properly but has the potential to be harmful if used improperly
Class 4Considered unsafe and dangerous for average use

Many red lasers fall under Class II, they are generally harmless but could be dangerous if shined in the eyes for a long period. Green lasers are much brighter and more powerful and fall under Class III. A green laser can be dangerous to eyes if shined directly into them for any amount of time or used for a prolonged period close to unprotected eyes. Class IV lasers are generally only used for scientific or military purposes and should never be able to be obtained by a layperson.

Caution with Green Lazers

Caution should be abundant when using a green laser pointer, even for outside use. Reflective materials such as a car mirror or antennae can pose a reflective hazard for these powerful lasers. If the user is not careful they can accidentally redirect a powerful laser into an unintended area or eyes.

Shining powerful lasers, such as green lasers, into any unauthorized areas, can be considered a crime and in some cases a very serious crime. Stories have been on the rise in recent years of people using powerful lasers to point at drivers and even planes, helicopters and military equipment. Authorities take these incidents extremely seriously because a laser can blind a human operating heavy machinery or even disrupt equipment which can be extremely dangerous to the victim and those in the surrounding area.

People who have been caught shining lasers improperly have been heavily fined and even jailed. Sensitive areas such as airports and military bases have been vigilant for improper laser use around their facilities. It is always better to be abundantly cautious when using laser pointers to make sure they are not shined at anyone by accident or anyone who is driving or flying equipment.

It would be prudent to check local laws and find any areas that might be sensitive to lasers in the area before using a laser of any kind outside.

Should I Still Get One?

People can still get laser pointers. When used properly, they pose very little risk and can be used in a variety of creative ways. As long as the risks are known and the right laser is chosen for the job there is no issue.

For anyone interested in getting a laser pointer for astronomy keep this in mind. Green lasers are the best for outdoor use and can be found online in a couple of different configurations. There are handheld lasers available as well as telescope mounted lasers depending on the preference. Recently, green lasers have become a lot more popular and therefore more available.

Make sure you are buying lasers from a reputable source. Lasers made overseas or that seem cheaply made can be dangerous or nonfunctional and it is best to avoid these. Handheld green lasers can be found all over the internet and are usually fairly cheap. Decent ones run around twenty dollars while good ones can run closer to fifty but they won’t break the bank.

A telescope mounted lasers are usually more expensive but a wide variety of different types, mounts and styles can be found on telescope accessory sites. These have the benefit of being customizable to a specific telescope style or need.

Due to their accessibility and price, a good green laser pointer can be a great addition to any astronomer’s arsenal. They can be fun to use to point out naked eye sky objects in the backyard with friends and family or configured to be mounted on a powerful deep space telescope. This makes them an extremely versatile tool that can enhance all matter of astronomy pursuits.