How to Detect an Exoplanet with Your DSLR

Photography Tips

Pointing a DSLR at the sky is a popular past time for many photographers, but detecting an exoplanet with anything less than a telescope is a bit, well, unusual. If you’re a photographer with a fascination for space and a love of DIY projects, this tutorial from IEEE Spectrum might be right down your alley. Using just his Canon EOS Rebel XS, a 300-millimeter Nikon telephoto lens, a Nikon to Canon adapter, and a homemade barn door star tracker, David Schneider shows us how to both track a star and calculate its brightness, allowing us to detect exoplanets:

What is an Exoplanet?

Exoplanets, also known as extrasolar planets, are planets that orbit stars other than our own. They’re of particular interest to those looking for the possibility of alien life, especially those that orbit their suns in the “habitable zone,” the distance from a sun where water can be present. (Via PetaPixel)

A few exoplanets have been imaged directly by telescopes, but the vast majority have been detected through indirect methods like the transit detection Schneider uses in the video. As it turns out, the brightness variations that occur when certain exoplanets cross in front of their host star are actually be big enough to be detected with a normal telephoto lens. That means that all you need is a way to hook up your DSLR to a star tracker, and boom! An exoplanet finder can exist right in your very own backyard.

By far, the most complicated part of the project is putting together the star tracker used to follow the stars as the earth rotates. Schneider provides a thorough tutorial in the video.

Materials Needed

• gears out of a defunct inkjet printer (funny thing is, most of us have one those!)
• a threaded rod bent into an arc “using a tree”
• an Arduino microprocessor
• an $18 ball head quick release plate bolted to the top, which allows the camera to be oriented in any direction

Tips for Using a DSLR Star Tracker

This is definitely a project for the committed DIYer! If you fit the bill and are considering diving into this project, here are a few things to keep in mind:

• Remember to align the hinge of your barn door tracker to your hemisphere’s celestial pole.
• Choose a fairly close star with a known exoplanet.
• The trickiest step is getting the camera pointed at your target star—use a right-angle viewfinder if you have one. Even so, it may take you a while to get your target star framed.
• Plan your shoot carefully using a transit guide. Transits that that occur during daytime or are too close to the horizon are impossible to observe. And of course, you need clear skies.
• You won’t be able to see the subtle variations of brightness from just looking at your images. Schneider uses the free software Iris to calculate the brightness both his own star and the four reference stars he’s comparing it to.

With any luck, you’ll be well on your way to finding an exoplanet!