After a telescope, this is the best astronomy educational tool I've seen. At night this AAA battery powered green laser pointer can seemingly touch the stars millions of miles away. Compared to a red laser pointer, the green beam remains visible and penetrates the air much farther. Because of its particular spectrum you see the beam and not just the end dot. Also, it's about 50 times brighter than an ordinary red laser pointer -- using the same safe low power. On a clear night it can easily shine a dot a mile away. With its sharp laser beam you can pinpoint the exact star you want, which greatly accelerates mapping and learning the constellations. I've been amazed at how much faster I've learned the heavens with one of these in hand.

The problem with green laser pointers has been their stiff price. Only recently have they dropped below $50, which is still a lot for an educational tool. Manufacturing green laser engines is more art than science so their actual power output varies by final pointer. The lasers are sorted after they are made. The select ones near to the legal "pointer" limit of 5 milliWatts are labeled as such and are priced around $100 these days. The others are labeled as "less than 5mW" or "guaranteed to be up to 5 mW" and are priced as cheap as $40, but their actual power is not stated. For a star pointer all you need is one of these cheap ones. I've been using an in expensive "up to 5mW" version that works wonderfully.

Incidentally, you can purchase higher powered green lasers from Wicked Lasers that exceed the mandated 5 mW. Their 15 mW green laser (6 mile range) goes for $100 and their scary/astounding 300 mW for $2000. These are incredibly bright at night, but overkill for an astronomy aid.

-- KK

BTG-2 Green Laser
<5 mW
$42
Available from Amazon

Starpointer
Full-powered 5mW
$110
Available from Sky Pointer

Wicked Lasers Classic
15 mW
$100
Available from Wicked Lasers