If the rising rates of melanoma, the deadliest form of skin cancer, doesn’t convince you to wear sunscreen (both indoors and outdoors, all year round), vanity might. After all, UV protection can reduce the number of wrinkles you get as you age, and may prevent dark spots on your skin, according to Adewole Adamson, a dermatologist and assistant professor in the Department of Internal Medicine at the University of Texas at Austin....

How to combine PDFs on macOS There are two ways to merge PDFs on Apple’s operating system, though one allows for more customization than the other. It’s also worth noting that these techniques allow you to combine any type of image file into a PDF, so you can tack a JPEG of a receipt onto the end of a PDF invoice if you want. Thankfully, Apple has a PDF combiner built right into macOS, and while Windows doesn’t have anything similar, there are some workarounds you can try....

While this is largely a good thing, it’s not without pitfalls. Have you ever tried to charge your computer from a phone charger? Or an iPad from your computer’s USB port? It happens at a crawl. If you want to charge all your devices efficiently, you need to understand what’s going on. How charging works Charging is a factor of three things you probably remember from high school: power (watts), current (amperes or milliamperes), and voltage (volts)....

Know your enemy We all have a “master clock” in our brains, the suprachiasmatic nucleus, or SCN. This region of the brain uses light and temperature to set an internal schedule that keeps us active and alert during bright, warm times, and makes us sleepy in cool, dark ones. Over time, your SCN gets used to a certain activity pattern—a circadian rhythm—and sticks to it by releasing hormones such as melatonin and cortisol....

Stats Time: 45 minutesCost: about $25Difficulty: Moderate Materials A stamp design, preferably printed on paperTranslucent tracing paper (or parchment baking paper)One block of stamp rubberA scrap of woodWood glue Tools A pencilA carving tool with a variety of tipsA permanent markerAn ink pad(Optional) hand saw(Optional) sandpaper Instructions Choose a design. The artwork you use should only feature one color other than the background, because the finished stamp will only be able to convey positive and negative space....

But masks aren’t exactly easy to come by: Medical-grade ones are already in short supply for healthcare workers who need them, so healthy people shouldn’t even try to purchase them. And in the wake of the CDC’s new recommendations, even non-medical cloth masks are sold out or backordered in many online stores. If you’re trying to figure out if and how you should cover your face on your next essential trip out of the house—for a walk on an uncrowded street or to buy necessary groceries, for instance—here’s a guide to all your options....

If you think about all the components that go into building a trail camera—detection circuits, infrared emitters, view screen, lens, and the waterproof housing it comes in—you’re getting a pretty good deal for not a whole lot of money. A good trail cam that will last you the entire year usually costs about $130. That’s not bad. It’s standing up to rain, wind, snow, and anything else Mother Nature can throw at it....

If you’ve ever misplaced your smartphone, you know how hard it can be to retrieve a lost device. So when you find a deserted device, you should return it as soon as possible. While you’re examining the area, do you see anyone looking around forlornly for their missing device? Observing the people around you is the quickest way to restore the phone, and it also ensures that you don’t accidentally steal somebody’s device while their back is turned!...

There are other tools out there you could install that will do the job, like RetroArch for Windows or Linux. But you could probably get a PhD in computer science in roughly the same amount of time it takes to set that application up. OpenEmu is the ultimate app for computer retro gaming, and the race is not particularly close. If you’ve already got a collection of ROMs on your computer, then I’ve got good news: all you need to do is drag the files onto the OpenEmu window....

Make sure your media source makes the grade A fancy TV is only as good as the content you push into it, which means that Roku box you bought back in Obama’s first term isn’t going to cut it for your new Ultra-HD setup. If you bought a smart TV, its native apps should stream at high quality, but here are some stand-alone boxes that can take full advantages of your new 4K set: Apple TV 4K ($179): It’s pricy, but it offers extremely high quality audio and video, as well as UHD movies in the iTunes store for $5....

While the story has all the uncanny ingredients of an Alex Jones-style conspiracy theory, it actually came from the Washington Post. Drawing on some questionable research, the article linked cellphone use to a supposed uptick in young people developing bone spurs at the back of their necks. Leaning forward to gaze at screens was apparently reshaping an entire generation—literally. But the devil is in the details. As scientists and science journalists quickly pointed out on Twitter, the research papers were limited by small sample sizes, the use of older adults as research participants, and, in some cases, the complete absence of key words like “phone....

This is not an exhaustive list, but these are some of the most popular and least expensive options worth considering. You’ve also got the option to combine some of these speaker setups together, so you don’t need to feel locked into one system or provider. Sonos Play speakers Sonos is generally considered to be the gold standard in terms of wireless home audio, offering a range of excellent-sounding speakers that can work independently or as a group....

How to take a Live Photo To access the four kinds of Live Photos, you first have to take a picture. Start by opening your Camera app and making sure Photo is highlighted among the side-scrolling options above the shutter button. Then, check the Live Photo icon at the top of your screen. If it’s on, it’ll display as three yellow circles. If it’s off, you’ll see three white circles with a slash through them—tap it to turn it on....

LI XIN ZHANG’S SUMMER CAMP began with sandwiches—not eating them but designing them. The rising seventh grader listened as teachers asked her and her peers to write instructions for building the ideal peanut butter, jelly, and bread concoction. Heads down, the students each created their own how-to. When they returned to the Zoom matrix of digital faces and told one another about their constructions, they realized something: Each of them had made a slightly different sandwich, favoring the characteristics they held dear....

The James Webb Space Telescope’s (JWST) new image of the Cartwheel Galaxy, located 500 million light-years away in the Sculptor Constellation, is the perfect example of a formation in motion. Previously documented by Hubble in 1996, its unique ring structure, which probably resulted from a high-speed collision between a large and small star cluster 200 million years back, is already showing signs of growth. Part of this is because JWST can detect stellar details otherwise obscured by cosmic dust....

After you’ve picked over the turkey carcass and officially bid farewell to Thanksgiving, it’s time to celebrate family and togetherness in a winter way: sawing off a life form’s vital organs, dragging it indoors, and keeping it unnaturally alive for several weeks. That’s right—we’re talking about Christmas trees. Joking aside, that “alive” part is key. Nobody wants to gather around some drooping, brown-needled vegetation. Luckily, extending the lifespans of these plants is easy—if you understand the science behind it....

Marcus is referring to how toxicologists got wind of New Jersey’s most infamous serial killer. In June 2003, a pharmacist at Somerset Medical Center in Somerville called the poison center after a patient nearly died of digoxin overdose. The woman wasn’t supposed to be on the heart medication at all, and the pharmacist wanted to know whether a Korean mushroom tea she had drunk might contain a botanical version of the drug....

Equipped with six instruments, including cameras and radar, the orbiter is providing scientists with the most detailed look at Martian landscape yet. One of the cameras, the High Resolution Imaging Science Experiment (HiRISE), snaps extremely high-resolution images of the Martian surface, giving scientists a clear view of the terrain. By studying the geology and climate of Mars, scientists hope to determine whether life was ever present, and whether it might someday be possible for humans to inhabit the Red Planet....

The new iPhones went on sale this morning and the big question, of course, is should you buy one? it’s a simple process to decide, actually. Ask yourself: “Does my phone still work and can it get the latest version of its operating system?” If the answer is yes, then you’re probably good with what you have. If the answer is “no,” then how are you reading this through all those cracks in your screen?...