Astronomy

The brain pathway that causes hairy mammals like mice and dogs to shake themselves dry appears to have more to do with pressure than temperature

The brain pathway that causes hairy mammals like mice and dogs to shake themselves dry appears to have more to do with pressure than temperature

Oil and water can be separated efficiently by pumping the mixture through thin channels between two semipermeable membranes

Oil and water can be separated efficiently by pumping the mixture through thin channels between two semipermeable membranes

When the 'God of chaos' asteroid Apophis makes an ultraclose flyby of Earth in 2029, our planet's gravity may trigger tremors and landslides that totally change the asteroid's surface.

As the International Space Station soared 257 miles above northern Mexico, NASA astronaut and Expedition 72 flight engineer Don Pettit captured this long-exposure photograph of city lights streaking across Earth while a green atmospheric glow crowned the horizon.

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.

NASA astronaut Suni Williams is in good health aboard the ISS, despite some speculation in the media to the contrary, agency officials stress.

Blood tests have shown that about 7 per cent of workers on dairy farms that had H5N1 outbreaks had antibodies against the disease

Blood tests have shown that about 7 per cent of workers on dairy farms that had H5N1 outbreaks had antibodies against the disease

When it comes to the survival of animals living in the wild, the characteristics of the group can matter as much as the traits of the individual, according to a study in marmots

When it comes to the survival of animals living in the wild, the characteristics of the group can matter as much as the traits of the individual, according to a study in marmots

The USS Cerritos' avian psychologist gets a taste of his homeworld.

With its purposeful design, does the Hawke Endurance live up to its good looks?

NASA's building a quiet fan to help future astronauts have some peace and quiet.

The controversies surrounding football’s video assistant referee (VAR) system highlight our troubled relationship with uncertainty – and point to potential solutions

The controversies surrounding football’s video assistant referee (VAR) system highlight our troubled relationship with uncertainty – and point to potential solutions

The climate impact of flights taken by the super-rich rose sharply from 2019 to 2023, fuelling calls for a carbon tax on private aviation

The climate impact of flights taken by the super-rich rose sharply from 2019 to 2023, fuelling calls for a carbon tax on private aviation

Data collected by the Zhurong rover and orbiting satellites suggests the existence of an ancient shoreline in the Utopia Planitia region of Mars