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DIY Exoplanet Detector

You don’t need a high-powered telescope to spot the signature of an alien world

5 min read
DIY Exoplanet Detector
Star Track: The rotation of the Earth causes stars to continuously shift position in the sky. Detecting the subtle signs of the existence of an orbiting exoplanet requires compensating for this shift. To do that, I built my own hinged “barn door” tracker.
Photo: David Schneider

Since 1995, when astronomers announced the discovery of a planet orbiting the star 51 Pegasi, exoplanets—which orbit stars other than the sun—have been a hot topic. I knew that dedicated amateurs could detect some of these exoplanets, but I thought it required expensive telescopes. Then I stumbled on the website of the KELT-North project at Ohio State University, in Columbus. The project’s astronomers find exoplanets not with a giant telescope but by combining a charge-coupled-device (CCD) detector with a Mamiya-Sekor lens originally designed for high-end cameras. That got me wondering: Might I be able to detect an exoplanet without a telescope or a research-grade CCD detector?

I discovered that one amateur astronomer had already posted online about how he had detected a known exoplanet using a digital single-lens reflex (DSLR) camera outfitted with a telephoto lens. He was able to discern the dip in the brightness of a star as an orbiting planet passed in front of it—a technique known as transit detection.

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From WinZips to Cat GIFs, Jacob Ziv’s Algorithms Have Powered Decades of Compression

The lossless-compression pioneer received the 2021 IEEE Medal of Honor

11 min read
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Photo of Jacob Ziv
Photo: Rami Shlush
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Lossless data compression seems a bit like a magic trick. Its cousin, lossy compression, is easier to comprehend. Lossy algorithms are used to get music into the popular MP3 format and turn a digital image into a standard JPEG file. They do this by selectively removing bits, taking what scientists know about the way we see and hear to determine which bits we'd least miss. But no one can make the case that the resulting file is a perfect replica of the original.

Not so with lossless data compression. Bits do disappear, making the data file dramatically smaller and thus easier to store and transmit. The important difference is that the bits reappear on command. It's as if the bits are rabbits in a magician's act, disappearing and then reappearing from inside a hat at the wave of a wand.

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