Our experts tackle the big questions that keep you up at night
If you started just before the first dinosaurs appeared, you’d probably be finishing your hike just about now.
Here’s how it breaks down: One light-year—the distance light travels in one year, used as the yardstick for interstellar distances—is about 5.9 trillion miles. If you hoofed it at a moderate pace of 20 minutes a mile, it would take you 225 million years to complete your journey (not including stops for meals or the restroom). Even if you hitched a ride on NASA’s Mach 9.68 X-43A hypersonic scramjet, the fastest aircraft in the world, it would take about 95,000 years to cover the distance.
You’ll need to bring a big bag, too; walking such a distance requires substantial supplies. The average adult burns about 80 calories per mile walked, so you’d need two trillion PowerBars to fuel your trip. You’d also produce a heap of worn-out shoes. The typical pair of sneakers will last you 500 miles, so you’d burn through some 11.8 billion pairs of shoes. And all that effort wouldn’t get you very far, astronomically speaking: The closest star to the sun, Proxima Centauri, is 4.22 light-years away.

Lost in drive-by country? Look for a cow. It will probably be pointing north—or south.

Dear EarthTalk: I am considering solar panels for my roof to provide heat for my hot water and possibly to do more than that. Are there some kinds of solar panels that are better than others? How do I find a knowledgeable installer? --Elise, Watertown, MA

Electron microscopes use a beam of electrons to magnify samples by up to 2 million times. But whatever they look at takes a beating, a problem when examining delicate biological specimens.

Lots of amphibians (a third to a half of all species) are dying, and their deaths are the breaking-edge of what many scientists are calling the first mass extinction since the dinosaurs checked out 65 million years ago, researchers say in a new paper published online in the Journal Proceedings of the National Academy of Sciences.

Scientists are not sure when this extinction crisis began—it could have started 10,000 years ago, or during the industrial revolution, or this century. But we are definitely seeing an extinction “spasm” right now, say the Berkeley scientists, especially among our clammy, froggy friends. This extinction is unlike the five that came before it, according to the paper’s authors from UC Berkeley, because it has nothing to do with any asteroid impact, or volcanic surge, or great sea cooling. Instead, it may have almost everything to do with us. Amphibians made it through last time, when the dinosaurs disappeared. But with new, people-driven pressures on biodiversity, the survivors are now some of the most vulnerable.

Almost 200 amphibian species have gone extinct in the last few decades alone, with several pressures adding to the crisis. One is a fungal skin disease called chytridiomycosis, which has been implicated in mass frog deaths in Central and South America, and is claiming species almost everywhere else on earth, according to the paper. Scientists believe the disease spreads on amphibians introduced by humans into new environments. Climate change is also implicated, possibly as a trigger for chytrid infections, but also as a force of its own. Many amphibian species are adapted to live only in a small temperature zone, and montane species are particularly vulnerable to temperature shifts that can shrink the small slice of mountainside they inhabit down to nothing.

Habitat loss is another important player, impacting 90 percent of the amphibian species the IUCN lists as at risk of extinction. Warming (and the weather changes that go along with warming) shrinks habitats, as does humanity’s constant bulging expansion over more and more of the earth. Research into treatments for chytrid is ongoing, with new results with beneficial skin bacteria, but with human-caused climate change progressing, and habitats shrinking, the papers authors close their report with the worry that we may not be able to make a dent in this latest mass extinction, and even if we can, we have very, very little time to do so.

Invisible Bullet-Tagging Technology Could Deter Criminals

A breakthrough nanotech coating for cartridges in firearms can transfer hard-to-remove tags to gun offenders and better capture DNA

Gun-slinging evil-doers beware. Scientific justice is just around the corner thanks to a new nanotechnology system that not only better captures DNA on guns, but attaches hard-to-remove, microscopic tags to the hands and clothing of criminals who fire their weapons. Developed in the U.K., the tags are a unique blend of naturally-occurring pollen, known for its extraordinary adhesive properties, and nanotechnology particles. The composition can be used as an abrasive coating to capture skin cells on gun cartridges, usually too smooth or shiny to retain much evidence in the way of fingerprints or DNA. The tags in the coating also transfer themselves to anyone handling the cartridges and are very difficult to wash off.

But the benefits of the nanotechnology don't stop there. Most evidence is usually destroyed after a gun is fired, because of the heat generated. The coating has been designed to avoid such heat damage and can even be varied subtly for every cartridge batch, making it easier for officials to tie guns back to the offenders. The breakthrough technology is cost-effective and could potentially be put to use within a year. Researchers may also consider applying the system to other weapons like knifes.