Despite living in it, we hardly know exactly how big the Milky Way is. But new research has provided us with an answer. Using a large survey of stars instead of just models (as previous researchers did), astronomers have now determined the disk of our galaxy to be 200,000 light years across twice as large as was believed a decade ago.

Astronomers know the Milky Way to be a spiral (螺旋状的) galaxy with a flat central disk composed of spiraling arms and a thin outer cloud of stars called the halo ( 光 晕 ). Most of the stars are found in the disk, which rapidly thins out at the edges. The size of the galaxy is measured from the point at which the number of stars in the disk significantly drops, so finding disk stars is key to determining the Milky Way’s size.

Coincidentally, disk stars tend to be much younger than the halo stars. Since stars gradually build up elements over generations, the disk stars’ composition can be different from that of the halo stars, allowing astronomers to figure out which stars belong to which population.

With a process known as spectroscopy ( 光 谱 学 ), researchers studied the chemical composition of over 4,600 stars from two surveys, and mapped out which stars are part of the disk and which belong to the halo. The results clearly show disk stars much farther from the center of the galaxy than before.

The researchers still believe the density of stars in the disk gets lower in an exponential ( 指数的) manner— just farther away from each other than previously thought. Although the galaxy has been supersized, it is still smaller than its neighbor Andromeda, which measures over 220,000 light years across. While our galaxy is looking larger, it ’ s not putting on much weight. Because the outer reaches are much less dense than the center of the galaxy, the additional area is only thinly populated with stars. These few extra stars are only a drop in the bucket compared to the rest of the galaxy, so overall the mass of the Milky Way remains largely unchanged.

Undoubtedly, music can comfort the soul for some, and it could also be a temporary reliever for physical pain. Listening to favorite songs could reduce people’s sensibility of pain, according to a new study published in the journal Frontiers in Pain Research. And the most effective pain relievers were songs describing bittersweet experiences and causing strong feelings.

The study invited 63 young adults to bring two of their favorite songs, which were required to be at least 3 minutes and 20 seconds long. One selection represented their favorite music of all time, and the other was the song they could use to comfort loneliness. The researchers also had the young adults pick one of seven songs that the team considered relaxing and were unfamiliar to the study participants. Each person experienced 7-minute blocks (隔音) where they were instructed to stare at a monitor screen while listening to their favorite music, or one of the seven relaxing instrumental songs, or a scrambled (打乱) version of both songs and the relaxing song chosen. One 7-minute block had people sitting in silence. All the while, the researchers stuck a hot object to the participants’ left inner forearms. When assessing their experiences, people were more likely to report feeling less pain when listening to their favorite songs compared with hearing the unfamiliar relaxing song or silence.

After interviewing the participants about the song they brought and their rating of pain, the researchers found people who listened to bittersweet and moving songs felt less pain than when they listened to songs with cheerful themes. People who listened to bittersweet songs also reported more chills — the thrill and tremble you get on your skin from listening to pleasurable music. “When people are listening to music they enjoy, by our measurements it can reduce the pain that we’re feeling by 10%,” said Patrick, a professor of biomedical and molecular sciences.

The atmospheric level of carbon dioxide (CO₂)—a gas that is great at trapping heat, contributing to climate change—is almost double what it was prior to the Industrial Revolution. This presents a challenge to researchers attempting to design artificial trees or other methods of capturing (捕获) carbon dioxide directly from the air. That challenge is one a Sandia National Laboratories-led team is trying to solve.

Led by Sandia chemical engineer Tuan Ho, the team has been working on a project using powerful computer models combined with laboratory experiments to study how a kind of clay can take in carbon dioxide and store it. “These fundamental findings have potential for direct-air capture; that is what we’re working toward,” said Ho. “Clay is really inexpensive and rich in nature, which should allow us to reduce the cost of direct-air carbon capture significantly, if this high-risk, high-reward project ultimately leads to a technology. What’s more, it can be used like sponges (海绵) to absorb carbon dioxide, and then the gas will be ‘squeezed’ out of and pumped deep underground.”

Carbon capture and storage is the process of capturing extra carbon dioxide from the Earth’s atmosphere and storing it deep underground with the aim of reducing the impacts of climate change such as more frequent severe storms, rising sea levels and increased droughts and wildfires. This carbon dioxide could be captured from fossil-fuel-burning power plants, or other industrial facilities or directly from the air, which is more technologically challenging. Carbon capture and storage is widely considered one of the least controversial technologies, to deal with climate change.

“We would like low-cost energy, without ruining the environment,” said Susan Rempe, a Sandia bioengineer on the project. “Direct-air carbon capture is important for reducing the amount of carbon dioxide in the air. We can live in a way that doesn’t produce as much carbon dioxide, but unfortunately, we can’t control what our neighbors do.”