Red or Green Laser for Astronomy

A commonly debated topic amongst astronomers, many people debate whether you should use a green laser or a red laser for stargazing. It is subjective, but I’ll give my opinion on this a little (but keep in mind it is my opinion).

A green laser will always be more effective for astronomy. The simple reason for this is that green lasers are more visible to users than red lasers and other colored lasers – that’s really it. Now, there are other things that we should consider which may help to explain why the green laser is more popular than it’s competitors.

We often get this question and the answer is simple: they’re just not nearly as visible! The color red is close to the infrared spectrum, which means it has much less energy than colors on the visible spectrum. So when a red laser makes contact with dust in the air or water molecules, its energy is simply absorbed as opposed to reflected.

One of the main reasons green lasers are so popular, particularly high-powered handhelds, is due to the light-saberesque beam the emit. They have a slightly wider aperture than a simple pointer and when the beam makes contact with particles in the air or atmosphere, it’s reflected; this is why the beam is so visible on a green laser.

Best Laser Color For Astronomy

The first topic I want to discuss is the color of the laser. This is very important and you should know that green lasers are the brightest because our eyes are most sensitive to this color.

In darkness – I assume you’ll be viewing stars in complete darkness – green is brightest followed by blue, red, and violet. What this means is that a green laser is most visible to your eyes, and the most commonly used color of laser pointer for astronomy.

Additionally, it requires less energy to produce the same laser brightness compared to other colors. We offer two types of green laser pointers, a 532nm and a 520nm version. While both are green, these operate very differently where the 532nm is a DPSS laser and the 520nm version is direct diode.

I won’t go over the difference in this article, for clarification on this and why the 520nm direct diode laser is the better choice, have a look at the laser guide. While green laser pointers are the most popular, red and blue lasers can also be used in astronomy.

My eyes are actually quite sensitive to blue in darkness, however, due to the high cost of blue lasers in the past, blue lasers were seldom purchased for this purpose.

In recent years, however, the cost of blue lasers have gone down dramatically hue to bulk production and new technologies arising making blue lasers a new, refreshing choice for astronomy laser pointers. Lastly, let’s touch upon red laser pointers. While not as bright, red lasers can also be used for astronomy as the laser beam can still be visibly seen – though not as well as with a green laser pointer.

While a laser pointer can be a useful tool for astronomy, not every laser is fit for this purpose. There are many models offered in various colors (wavelengths), power outputs, and prices, which one do you actually need?

Laser Power Output

If you know about lasers, you’ll know that power output determines brightness; the higher the power, the brighter the laser will be. Of course, this is relative only to a specific wavelength.

For example, a green and red laser at the same power output will not have equal brightness. In this example, the green laser will be brighter. For some laser pointer vendors, they may recommend their highest powered, most expensive laser pointer. Although you may “wow” your audience initially, a bright laser may disrupt your night vision leaving your eyes adjusting every time the laser is turned on.

Hence, I actually never recommend anything that is too powerful. The key is to purchase a laser pointer that is bright enough where the laser line can be clearly seen, however, not so bright that your eyes refocuses.

In my opinion, you should opt for a minimum of 5 mW laser pointer in either green or blue.

What model and how much should I spend?

Laser pointers have evolved throughout the years and now come in all shapes and sizes from key chains, to pen-styled, to larger flashlight-styled lasers in a multitude of powers. Some laser pointers go as far as replicating what a laser sabre (from Star Wars) looks like!

First, I don’t recommend the large, flashlight styled lasers mainly because they are heavy and inconvenient. These lasers barely fit in your pocket, so unless you want to hold it throughout the night, be our guest! Also, the larger lasers usually mean higher powers which is usually too powerful for star gazing.

You should stay away from the key chain lasers as well as these are usually weak in power and poorly made. For 532nm green laser pointers, always ask if the product is equipped with an IR filter. Generally speaking, what you should look into are the pen-styled lasers or something just slightly larger. These often times are powered by AAA batteries and offer power ranges that are perfect for astronomy purposes.
If you intend to attach the laser pointer to a telescope, I suggest looking into a laser pointer that makes it specifically easy to do so (it should say in the guide). While pen-sized laser pointers were not meant for extended use (the average laser pointers should not be turned on for more than several minutes at a time), this is another condition that you’ll want – you need a laser pointer that stays on continuously.

Conclusion

You shouldn’t just buy any laser pointer. Before purchasing a laser pointer for astronomy, you need to ensure that you;

  • Do proper research on which model you need.
  • Decide on the color that you want to opt for (I say green or blue, but it’s up to you).
  • Get the right power output for your needs.
  • Opt for the right model.

If you do all of this correctly, then you’ll undoubtedly end up with a solid laser pointer that will work well for you.