Chuck Schumer knows the writing is on the wall for his time as Senate Majority Leader. Schumer, who has led Democrats in the Senate for the past four years, suggested in a statement that the new Senate…

Professors at Columbia University are reportedly offering to drop upcoming midterm exam scores and cancel classes to support students who are distressed over the results of the presidential election. …

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Campaign promises are sometimes as ephemeral as a spring breeze. President-elect Trump (I will never get tired of typing that out) has a better record than most on this score; even my far-left proggie…

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If I ask you to picture a radio telescope, you probably imagine a large dish pointing to the sky, or even an array of dish antennas such as the Very Large Array. What you likely don’t imagine is something that resembles a TV dish in your neighbor’s backyard. With modern electronics, it is relatively easy to build your own radio telescope. To understand out how it can be done, check out a recent paper by Jack Phelps. He outlines in detail how you can construct a small radio telescope with a 1-meter satellite dish, a Raspberry Pi, and some other basic electronics such as analog-to-digital converters. It’s a fascinating read, and one of the most interesting features is that his design is tuned to a frequency of 1420.405 MHz. This is the frequency emitted by neutral hydrogen. Since it has a wavelength of about 21 centimeters, the hydrogen emission line is sometimes called the 21-cm line. Neutral hydrogen comprises the bulk of matter in the Universe. The 21-cm emission isn’t particularly bright, but because there is so much hydrogen out there, the signal is easy to detect. And wherever there is matter, so too is the hydrogen line. Observations of hydrogen in the Milky Way (red dots). Credit: Jack Phelps The emission is caused by a spin flip of the hydrogen’s electron. It’s a hyperfine emission, which means the line is very sharp. If you see the line shifted a bit, you know that’s because of relative motion. Astronomers have used the line to map the distribution of matter in the Milky Way, and have even used it to measure our galaxy’s rotation. Early observations of the line pointed to the existence of dark matter in our galaxy. And now you can do it at home. There are other radio objects you can observe in the sky. The Sun is a popular target given its strong radio signal. Jupiter is another somewhat bright source. It’s a cool hobby. Even if you don’t intend to build a radio telescope of you’re own, it’s worth checking out the paper just to see how accessible radio astronomy has become. Reference: J. Phelps. “Galactic Neutral Hydrogen Structures Spectroscopy and Kinematics: Designing a Home Radio Telescope for 21 cm Emission.” arXiv preprint arXiv:2411.00057 (2024). The post You Can Build a Home Radio Telescope to Detect Clouds of Hydrogen in the Milky Way appeared first on Universe Today.

Not just one but three different versions of "Hotel California" made the cut. Continue reading…